Mothers letting go: postnatal maternal investment shapes sex-specific social development in wild vervet monkeys

42 Se x diff erence s in be ha viour , part icul ar l y i n soc ial s trategie s, a r e pe r si stent among s e x ually 43 repr oduc ing animal s ( Kappele r , 2 017 ). T h ese d iff er e n c es in beh a viour are largel y dr iv en b y 44 anis og am y , cr eat ing an initia l asymmet r y tha t lea ds to dis t inct e v olu t io nary pa thwa y s towar ds 45 the h i g hest f itnes s (Kokko & J e nnion s, 2 008; Sc härer et al. , 2012 ) . While widespr ead, these 46 diff erences in beha viour ar e not fix ed, but ar e fle xible and shape d b y ecologica l cons t raints, 47 soc ial s y st ems and t he costs and benefits of par ental c ar e f or eac h sex (Kappele r , 2017 ) . In f ac t, 48 m oth e r s – t h e ge n e r al p r i m e ca r e g i v e r o f y ou n g i n m a mm al s ( C l u tt o n - B r o c k , 1 9 9 1 ) – a r e k n o wn 49 to adapt t heir beha vio ur , bot h t ow ards their offspr ing as well as t o w ar ds oth er g r oup mem be rs , 50 bas ed on the offspr ing ’s s e x ( Guinn e ss e t al., 197 9; Hewiso n & Gaillard, 1999 ; Ishizu ka & Inoue, 51 2023; K osk ela et a l. , 2009; K ulik et al., 20 16; Lonsdor f, 2017; Maes t r ipi er i , 2 018; Murr a y et al., 52 2014; R obe rt e t al., 2 010 ) . T he mec hanisms throug h whic h mo t he rs sha pe thes e se x - s p ecific 53 tr a ject or ies c an v a ry; ma t e rnal eff ect s do not need t o be e xp re ssed pr imarily thr ough se x 54 alloc a t ion a t bir t h or e ne rge tic p ro vis i oning b ut ma y inste ad o p e r ate t hro ug h pos t nat a l socia l 55 de v e lopmen t and so cial s haping. 56 Se x - bia sed pa rental in v e s tment, bo th pre- and po st-natal, in offspr ing is a long-s t a ndi ng 57 re sear c h are a in e v ol utionar y biology (s ta rting with D a rwin, 1871 ). Ac cor di ng t o t he par e nt a l 58 in v es tment t he ory ( T ri v er s, 1972 ) , the relati v e in ve stment ( i.e ., an y in v estmen t b y a p ar ent in a n 59 i n d iv i d u a l o f f s p r i n g th a t i n c r e a s e s th a t o f f s p r i n g ’ s s u r v iva l) i n th e s exes sh a pe s p a t t e r n s o f 60 compe tit i on and ma te c h oice ( also c alled “con vent iona l se x r oles ” , K okk o & Je nnions, 2008 ). An 61 of ten disc ussed applica tio n of t his fr amewor k i s t he T r i v e rs-Willar d hypoth e si s (TWH ; T r i v e rs & 62 Willar d, 197 3 ), w hic h pr e d ic ts how mot her s s hou ld adjust their in v e stment bo th pr e - a nd post-63 n a ta l s o th a t t h e s e x r a ti o o f t h e i r o f f s p r i n g i s b a s e d o n th e i r o w n p h y s i c a l c o n d i t i o n o r s o c i a l 64 rank. In po l y gynous s pecies, w here male rep r o d uc ti v e suc ce s s i s e x p ect ed to v a r y mor e and i s 65 po t entia ll y m ore dependent on indi vid ual q ua lity – while f e ma les us uall y repr oduc e r e g ard l es s 66 of c ondit i on, high-q uali ty f e ma les shou ld bias i n v estment t ow ards s ons ( T r i v e rs & Willar d, 67 1973) . How e ver , lif e-history ana l y se s high ligh t tha t suc h p redictions de pend on ma t er nal age, 68 re sidual rep roducti v e value, and the p r e dictabili ty of fitness r e t ur ns , r ather th an condition alo n e 69 (Le imar , 1996 ) . In these mo d e ls, mot h ers ma y f a vour the se x wit h more r e liable or im media t e 70 .CC-BY-NC 4.0 International licenseavailable under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprintthis version posted February 17, 2026. ; https://doi.org/10.64898/2026.02.16.705899doi: bioRxiv preprint repr oduc ti ve pa y offs w hen fu t ur e re pr o duct i v e oppor tuni t ies decline, or w he n s ocial a nd 71 ec ologica l c onstraint s aff ect the e xpe ct ed benefits of p roducing so n s v e r sus d a ugh t ers (L eima r , 72 1996) . In spe c ies wit h se x-biased d ispe r s al, materna l in v e s tme nt st r ate gies can be furt her 73 sha ped b y the soc ial cons equenc es of offspr ing r esidency , s ince offs pring s e x det er mines fut ur e 74 e xpo sur e t o kin c ompet i tio n and ac ce ss to soc ial allies. The “ lo cal r e source compe t iti on ” (LR C) 75 h ypot hes is p ropose s that mo t hers ma y f a vour the dis pe r s ing s e x w he n local c ompe titi on is high, 76 par tic ularly f or low -ranking f ema l es (Clar k, 1978 ). In co ntrast , t he “l ocal reso ur ce 77 enhanc emen t ” ( LR E) h ypothesis p re dic t s that in v es tment in the phil op atric s e x ma y be 78 benefic ial when o f fs pring s t r eng the n the mat riline or p ro vide s ocial s upport , es pecia ll y f or high-79 ranking f emales ( Emlen e t al. , 198 6) . These framew or k s, w hile no t m utua l l y e x clus i v e, 80 emphas ize t hat s e x-biase d maternal in ve st ment is a fle xible s t r ateg y tha t i nte gr ates bo t h 81 interna l st ate a nd e xter nal so cial s t ruct ure to maximiz e li f et i me fit nes s ret urn s. 82 Ma t er nal in v es tment int o t heir offsprin g can be e xpr es s ed thr ough a wide range of mec hanisms 83 operating ac ros s dif f e r ent de v e lopmental stages , both pr enatally a nd po stnatall y . Mo the rs ma y 84 adjus t the s e x r a t io of their offs pring bef ore bir th bas ed on their own ph y sic al c ondition or 85 soc ial r ank, to maximize f it nes s returns ( T r i ve r s & Willar d, 19 73 ) . In t am mar wallabies 86 ( Nota mac r opus eugenii) , f or e x a mp l e, mo ther s with highe r “in v es tm ent abili ty ” wer e 87 sig nif ic antl y mor e lik el y to gi v e bi rth t o sons ( R obert et a l., 20 10) . Mat er nal e f f e cts can als o 88 indir e ctl y s hape offspring phenotypes throug h prenatal horm onal e xpos ur e (Quinli v an et al. 89 1998; H a nsen et al. 1 999 ; Le sag e et al. 2001 , 2 004; S eckl 2 001; W alk e r et al. 2001), influencing 90 la t er be ha vioural predi spos itions (W alle n & H as sett , 2009) . Aft e r birth, m ot her s ma y further 91 adjus t t heir in v estment throug h the d ir ec t tr a n sf er o f resources o r ph y s ic al eff or t t o offspring 92 bas ed on their s e x; p roducing riche r o r mor e milk f or a s p ecific se x (Hinde, 2 009; K osk e la et al., 93 2009) , or di rectl y adjus tin g their pro ximity and gr ooming behavio ur t ow ards offsp ring 94 (Bentley-Condi t , 2003; F ai rba nk s & McGuire, 1987; K ulik e t al., 2016 ) . 95 I n p r i m a te s i n p a r ti c u l a r , t h e s e p o s t n a ta l i n v e s t m e n t p a t t e r n s a r e c l o s e l y l i n k e d to th e 96 de v e lopmen t of s e x-spec ific s ocial t r ajec t ories . Philopa tr ic imma t ure f em ale s f or m stronger 97 bonds w it h ma t e rnal kin than ma les d o ( Amici et al., 20 19; Lon sdor f, 2017; Maes tripier i , 2018 ), 98 w hi le ma les of ten se ek cont ac t w it h ot her males o r age-pee r s, potent iall y to form allia nces a nd 99 pr e pa r e f or di spe r sal (Crock ett & P o pe, 199 3; Lons dorf, 2017 ; Mae s tripie r i & R oss, 200 4) . 100 Mo t her s ma y acti v e l y f acilita t e t hese di ve rge nt path w ay s b y sha ping o f fs pri ng so cial e xpo s ur e 101 (Amic i et al ., 2019; Castella no-Navarro et al. , 20 23; Maestripier i, 2018 ), as sho wn in ma le-102 phil opatric c himpanze es, w here moth er s o f s ons sp end more time in g r o ups c ontaining adult 103 males ( Murra y et a l., 2 014 ); p o t e nt ia l l y t o pr epa r e them f or their fut ur e social en vironment 104 (Lo nsdorf, 2 017 ). Lik ewi se , mother s might e n c our a ge s on ’ s di s p ersal in f e male-p hil opatric 105 .CC-BY-NC 4.0 International licenseavailable under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprintthis version posted February 17, 2026. ; https://doi.org/10.64898/2026.02.16.705899doi: bioRxiv preprint spe cie s b y e xhibiting highe r rat es of a g gr e s sio n t owar ds sons (K ulik et al. , 20 16; Timme, 19 95) , 106 w hi le f or mi ng generall y s tr onger bonds with their da ugh t ers (the philopa tric se x ; e .g., Ishizuka 107 & Ino ue , 2023; K ulik et al. , 2016 ). Thes e p a t t e rns s ugges t that ma t ernal in v e stment g oe s be yond 108 ener getic p r o visioning, but al so prepar es offs p ring w i th their fu tur e se x- s pecific r ole s . 109 Prima t e s pr o v id e a str ong s t u d y sy s t e m for e x amining s e x-biased mat ernal in v e stment and its 110 de v e lopmen tal conse quences . Their slo w l if e his tories, e xt ended pe r iods of ma t erna l c ar e a nd 111 comp lex soc ial sy s tems allow ma te rnal ef f ec ts t o p o te nt ial ly accu m ula t e o v er lo n g 112 de v e lopmen tal windo w s, making them useful f or link i ng ea rly e xpe r ience s t o adult s ocial roles 113 and potent ia l fit ness ou t c o mes ( Lon sd or f, 2017 ) . Mo r eo ver , f emale philopa tr y in man y p rima t e 114 spe cie s cr e at es p redictable s e x diff erence s in di spe rsal, kin c ompetitio n a n d c oalitionary 115 behavio ur , off e ring a nat ur al co ntext i n w hic h to st ud y the predict ions of T W H, LR C and L RE 116 (Cla rk, 1978; Emlen e t al., 1986; T ri v er s & Willard, 1973 ) . Within t his fr a me work, long-ter m 117 field studies are uniquel y pos it io ne d to s tud y v a r iation in ma t ernal a ge, rank , offspr ing sur v i v a l 118 and soc ial integr a tio n . V e rv e t monk ey s ( Chloroce b us p y ge r ythrus ) p rov i d e a n e xc e l l e n t m o d e l 119 f or ex amining sex-biased mat e rnal in v es tment w ithin a f ema l e-p h ilo pa t r ic prima t e socia l 120 sy stem. F emale s r emain in t heir n a ta l groups and f or m s ta ble, mat rilineal dominance 121 hierar c hies , w hereas males di s p e r se at ma t ur ity and mus t establis h rank and socia l 122 relationships in new g roups ( B orgea ud e t al. , 2016; Che ne y & Sey f arth, 1990; H e melrijk et al., 123 2020) , f or ming d yna mic m ul ti ma le /m ul t if e ma le gr oups . Ma ternal dominanc e rank i n v erv et s 124 has been f ound t o predict the majority of conflic t s of o f fs pring (Horrock s & H un t e, 1983) . 125 Matin g is pol y g ynous, with li tt le r epro ducti v e s k ew (Che ne y et al., 198 8; Minkner e t al., 201 8; 126 W eingr ill et a l., 20 11) , and highly sea sonal (Che n ey et a l., 1988 ) . F emales usual l y gi ve birth t o 127 their f ir st offspr ing w he n t hey are t hr ee y ea rs old, and then con tin uo us l y one offspr ing per y ear , 128 being a f ast g ene r a tion tur no v er f or pri ma tes and enabling us to hav e a large s ample size f or t his 129 stud y . Mo the rs ca rry their inf ants f or appr oximat el y the fir st three mon t h s, but in f a n t s g a in 130 slo w l y m ore independenc e dur in g that period ( F ai r bank s & Mc G uir e, 198 7) , while als o r e cei ving 131 high in t er e st and alloparental care fr o m o ther g r oup me mber s, mainl y f ema les (F rut eau et al., 132 2011) . The pr onou n c ed se x diff erenc e in di spe r s al creat es pred ictabl e a sy m metrie s in futur e 133 soc ial en vi ronments, kin competi tion, and fitness r etur ns . Long-t er m data fr om we ll -ha bitu a t ed 134 wild- li ving groups ther e f or e allo w e nerge t ic in v estment and socia l s caff oldi ng to be e v alu a t ed 135 toget her within a s ingle natural s y st em. 136 In t his s tud y , w e use lo n g -ter m be ha v iour al and demographic dat a f ro m a w il d- li v i ng pop ula t io n 137 of v erv et monk e ys to e x amine ho w maternal a ge and dominance r ank s hape sex-bias e d 138 de v e lopmen tal trajec t or ies. Spe cifical l y , w e t est w het her ( i ) offsp ring sex r atios at birth v a ry 139 wit h ma t er n a l age and dominanc e r a n k, a s p r edic t e d by T ri v er s-Willard- type a llocati on mode ls 140 .CC-BY-NC 4.0 International licenseavailable under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprintthis version posted February 17, 2026. ; https://doi.org/10.64898/2026.02.16.705899doi: bioRxiv preprint and loca l re source c ompetit i on/ enh anceme nt fr a mewor k s (Côté & Fes ta-B ianc he t, 2001; 141 Maes tripier i , 20 02 ; Trive rs & W illa rd, 1973 ); (ii ) mat ernal rank , age and p re senc e inf lu ences 142 sur vi v a l to adu lt h ood for s ons and da ugh ter s, cons i stent w it h sex-spec i fic vulner a bilit ies a nd 143 rank-mediated a d v ant ages ( H or r oc k s & H un te, 1983; Meikle & V es se y , 19 8 8) ; ( iii) materna l 144 in v es tment across d ev elopment – c onsidered thr ough indirect ( r ep roducti v e pacing) and di r ec t 145 in v es tment ( mat ernal pr oximity , grooming a nd co alitio n a ry suppor t t ow ards the off s pring) – 146 v ar i es b y offspring sex a n d mater nal c har a cteris t ics (Maest ripieri, 2018 ); and ( i v) offsp r i ng 147 soc ial e xpos ur e and eng a gement wi th ot her g r oup mem ber s align wit h thes e ma t erna l 148 in v es tment pat t e rs, as e xpec t e d if ea r l y e xperienc e i s tuned t o fu ture sex-spe c i fic r o les ( Ishizuka 149 & Ino ue, 2023; K u lik et a l., 20 16; Lo ns d o rf, 20 17; Mur r a y et al., 2014 ). B y int e gr a t ing these 150 comp one nts w it hin a sing le p o pula t ion, we aim to c larify w het her se x-bias ed mater n a l 151 strat egies in this f emale-p hil opatr ic prima t e ar e be st underst ood as d iff e r ential energetic 152 i n v e s tm e n t, d i f f e r e n t s o c i a l s c a f f o l d i n g , o r a c o m b i n a t i o n o f b o t h . W h i l e T r i v e r s - W i l l a r d m o d e l s 153 (T r i v e rs & W illa r d, 19 73) e mphasize fitness max imization thro ugh c ondition-depende nt se x 154 alloc a tion, o ur stud y t es ts w he t he r ma ter nal eff ec ts operat e p r imaril y thr ough s e x-s p e cific socia l 155 pr e pa r a t ion r a t he r than diff er e nt ia l ener getic in v e s tment. Gaining a bet t er under standing of 156 how s e x es de v elop, di v erge and a re tr eat ed b y their mothers and other group mem ber s will he lp 157 us she d light on the dev elopment o f primat e soc iality a nd the ev olu tion of se x roles , w hic h 158 remains a poor l y understood aspe ct of (hu man and nonh uman) p r imate behaviour al ev olut i o n 159 ( M a e s tr i pi e r i , 2 01 8) . 160

161 O ur aim w a s to e x amine ( i) w he the r offspr ing se x r at ios a t bir t h va ried w ith mater nal age a nd 162 dominanc e r ank ; (ii ) how mater nal r a n k and materna l pr esence inf lue nced offs p r ing s urvi v a l to 163 adul t h ood in son s and daugh ter s; ( ii i) how ma ter nal age a nd r ank s haped pa t ter n s of materna l 164 in v es tment acro ss offs p ring d ev elopment , including reproducti v e pacing , spa t ia l a s socia t ion, 165 groomin g, and co alitionary s upport; and (i v) w het her se x diff erences i n offspr i ng socia l 166 e xpo sur e and eng age ment wit h group mem ber s w er e c onsi ste n t wi t h t hese materna l 167 in v es tment pat t e rns. 168 Data col le cti on 169 W e s tu d i e d w i l d v e r v e t m o n k e y s a t th e i N k a w u V e r v e t P r o j e c t i n M a w a n a G a m e R e s e r v e , S o u t h 170 Africa . While the project star t e d in 2 010, reliable beha vio ur al data o n f o u r groups c ould be 171 col l ect ed fr o m 2012 on w a r ds. B e ha vio ural data col lec tion pr o t oc o ls cha nged in 2022 , gi ving us 172 10 y e a r s of c onsist ent , r elia ble beha viour al data ( 2012 -2022 ) . Beha vio ur al data neede d to 173 ca lcu la te mater nal r ank remained con s i stent o v er the dat a c ollect ion pr ot oc ols, allow ing us to 174 .CC-BY-NC 4.0 International licenseavailable under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprintthis version posted February 17, 2026. ; https://doi.org/10.64898/2026.02.16.705899doi: bioRxiv preprint ca lcu la te ma ter nal r ank from 2012 to 2025 . D emog r aphic da ta c ollect i on r emained cons i s tent 175 o v e r the y ear s, gi ving us 15 yea r s of d emographic data ( 2010- 202 5). F or an o v er view of w hic h 176 d a ta w a s u s e d f o r w h i c h q u e s t i o n , s e e T a b l e 1 . D a ta w e r e c o l l e c t e d i n f o u r n e i g h b o u r i n g , w e l l -177 habi tua t ed groups (AK: mean group s ize 25 .66 indi viduals , BD : mean group size 50 . 83 178 indi viduals , KB : me an gr o up siz e 17 . 9 8 ind ividuals, NH: mean group size 37 . 98 indi viduals ) , f or 179 w hic h al l indi viduals w ere indi vidua ll y identified. Obser v e r s s tart ed da t a colle c tion af t er pa ssing 180 sev e ral quality con tr o l t es ts, suc h as i nt erobser v e r r elia bilit y s cor ing – pa s sing at least 80% of 181 the kappa c oefficie n t – w it h the on-s it e scientific o r field mana ge r , a s w ell as identification t ests 182 o f a l l i n d i v i d u a l m o n k e y s i n th e g r o u p s . D a ta c o l l e c ti o n w a s c o n d u c t e d s i x d a y s a w e e k , w i t h a n 183 a v er ag e of 6 .8 hour s o v e r 4. 2 obs e r v a tion d ay s pe r gr oup, b y on a v e rage 2 .4 obs er ve r s , since 184 2012 (start of t he data per iod) . 185 Ta b l e 1 : o v erview o f data used f or e a ch par t of o ur a n a l yse s, inclu d in g the tim e-per i od used a n d the n umber of 186 o f f sp ri n g an d m o t h er s . 187 Qu e s tion Ti m e - pe ri o d n o ff sp ri n g; n moth e rs (i) Sex a ll o c a ti on at b ir t h 2012 -2025 330 ; 98 ( i i) O f fsp rin g s u r v i v a l 2012 -2023 304 ; 94 (iii) Ma t e r nal in v e s t ment ( IBI; p r ox imi ty ; gr oom i ng; su p port ) 2012 -2022 222 ; 81 (iv ) Soc i al ex po su re a nd eng a g e men t off sp rin g 2012 -2022 222 ; 81 Births, d e aths and group comp osition w ere moni t or e d da il y . F or each inf ant , s e x w a s r ec or d e d 188 w hen ev er possible. Bec ause male s di s perse at appro ximat el y 4 y ears old and f ema les s tart t o 189 repr oduc e at around 3- 4 y ears of age, we res tr icted our sur v i v a l ana l y ses to s urvi v al up to 3 190 y ea r s of age ( w hic h we c onsidered ad ul t ho od), while both s ons and daughter s still r es i ded in 191 their natal groups. 192 Mo t her s ’ ages w e re known from long-term r e cord s or e s tima t e d from repro duct i v e histor y at 193 the beginnin g of t he project . Mat e r n a l domina nce r ank w a s e stima t ed using Elo-ratin g 194 pr o cedures based on agonis tic inter ac t ions among adul t f e male s and w ere a v er a ged p e r 195 ca lendar y ear; gi v e n the stability of f e male hier a r c hies in this s pecie s (Borgeaud et a l., 2017; 196 Chene y & Se yf ar t h, 1990 ). Beha viour al da t a on mother -of f s pring int e r ac tions and agonistic 197 behavio ur w e r e c ollec t e d throug h a d libitum a nd gr oup s can sampling. F o r e ach mot her -198 offspr ing pai r and obs e r v ation y ear , w e calc ula t ed sev e ral binomia l r e s po nse v a r iables: (i) 199 pr oximity of mo ther t o t he inf a nt, whe r e e ach scan obse r v a t ion wher e the in f ant w as r ec or de d 200 .CC-BY-NC 4.0 International licenseavailable under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprintthis version posted February 17, 2026. ; https://doi.org/10.64898/2026.02.16.705899doi: bioRxiv preprint within 5 met er s of t he mother w as r ecor de d a s a succ e s s (1 ) , co mpar ed t o e a ch s can perf orme d 201 on t he m ot her r e g ardles s of the pro xim ity to her offspring (0) ; (ii ) grooming i n v es tment in t o t he 202 inf ant b y t he mo the r w her e ea ch gr oomin g bo ut w her e the mo t her g r oomed the inf a n t w as 203 recorded as a suc cess , compa r ed t o each time the mo t her w as r ec or de d g r oo ming an y g roup 204 m e mb e r; ( i i i ) m a t e rn a l c o al it i o n ar y su p p o r t to t h e i n f a n t , w h er e ea c h co n f l i ct w h e r e th e moth e r 205 suppor t ed t he inf an t w as record ed as a s uccess , c ompar e d t o the t o tal nu mber o f c onflic ts in 206 w hic h the in f an t was in v ol v e d; (i v) th e amo unt o f offspr ing socia l e ng agem e n t and e xpos ur e, 207 w here the nu m ber of grooming in t er a ctions or c onflicts in w hic h the in f ant w as in v ol v e d wer e 208 recorded a s a suc ce ss, compared to t he to ta l n u mber of groo ming in teract ions or conflic ts 209 recorded in the group; the a ver a ge di stanc e of a mothe r t o adul t group mem b ers dur ing the fir s t 210 y ea r aft er an inf ant’s birth, ca lcula t ed a s a continuo us numer ical v alu e a n d modelle d us ing a 211 Gam ma dis t r ibuti on. The a ver ag e dista nc e of a mo t her t o adu lt gro up mem ber s ( off s p ring socia l 212 e x p o s u r e ) w a s o n l y c o n s i d e r e d i n th e f i r s t y e a r o f a n o f f s p r i n g ’ s l i f e a s j u v e n i l e v e r v e ts g a i n 213 independenc e rather quickl y ( F air ba nks & Mc Guire, 198 7 ), a nd f emales gi v e birth to new 214 offspr ing a lmost ev ery y e a r (~1.3 ye ars, this stud y). An obs e rv ational year star t ed a ft e r t he 215 (estima t ed) dat e of birth of the inf an t . Most births in our populati on w ere rec or ded betw ee n 216 Oc to ber and Januar y ( 9 7.2 % of birt hs ) . 217 Statistic a l anal yses 218 All anal y s es wer e conduc ted in R ( v ers ion 4.3 .2 ) using t he pa c kag es glm mT M B, lme4, DH AR M a , 219 and emme ans (B rooks e t a l., 201 7; Hart ig, 202 4; Le nth & Piaskow ski, 20 17 ) . F or eac h bi rt h, w e 220 s co r ed i n f a n t s e x a n d i n f a n t s u r v i v a l a s a b i n a r y v a r i ab l e . I n t e r- b i rth i nt er v a ls w er e ca l c u l a t ed i n 221 y ea r s f or each mother-y ea r c ombination and us e d in t he se x - rat io ana l y s e s as a p r o x y f or 222 ma t er nal r eproducti v e pac e and pot e ntial co sts of producin g a gi v e n s e x. F or the behavio ur a l 223 datas ets, offsp r ing age w as e xpre s s ed in ye ars , and beha v iour al mea sur es w ere e xp re ssed pe r 224 y ea r of ag e (1-3) . F or the statistic al a nal y se s , inf ant a ge w as mean-ce nt red, and mothe r age , 225 rank, number of f e ma les and int e r-birth int er v als w ere standa r diz e d and ce nt red. 226 T o t e st whe the r ma t e rnal r ank, age or num ber of f e ma les p res ent in the gr oup during the 227 pr evious matin g season influenc ed t he probabili ty of producing a sp e cific s e x, w e fitt ed a 228 bino mial generalized linear mix e d m odel per inf ant bir t h. O ur r e s pons e v ar iable, sex of the 229 inf ant (0 f or sons, 1 f or d augh t er s ) w a s fitt ed wit h a logi t- link using a bino m ial f a mily . As fi x e d 230 eff ec ts, we included ma t e rnal rank, maternal age, num ber o f f ema les pr e s ent i n the group d ur in g 231 the pr evious matin g se a son and the gr oup identi t y . W e included random int e r c ept s f or mot her 232 ident it y and offspr i ng birt h y ear to acc oun t for r epea ted measure s w ithin m ot her s and c ohort -233 le vel dif f er e nces among bir th year s . Ma t e rnal a ge and rank w er e weakl y ne g ati v el y cor r ela t e d ( r 234 .CC-BY-NC 4.0 International licenseavailable under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprintthis version posted February 17, 2026. ; https://doi.org/10.64898/2026.02.16.705899doi: bioRxiv preprint ≈ - 0 . 1 5 ) , a n d P C A d i d n o t r e v e a l a d o m i n a n t s h a r e d a x i s . V I F v a l u e s w e r e n e a r 1 , c o n f i r m i n g 235 neglig ible co lline arit y , so b oth v aria bles we r e us ed a s sepa rate predictor s of ma ter nal qua lit y . 236 T o tes t f or se x-s pecific e ff e ct s of mater nal r ank, - a ge , and -deat h during c hildho od on offspring 237 sur vi v a l to age 3, w e fi t ted anot h er bino mia l generalize d linear mix ed mode l wit h binary 238 sur vi v a l as our r espons e v ar iable. Onl y inf ants born befor e 2023 w e r e i ncluded in sur vi v a l 239 anal ysis , e nsuring that surv i v al out c o mes t o age 3 w e re kno wn at time of analy sis. Our fix ed 240 pr e dict or v ariables consi s t ed of t he sex of t he inf an t in an in t eraction wi th bo th t he mo the r’s 241 rank, the mo ther ’s ag e at birth and a bi nary v a r iable indicating whet her the mo t her died dur i ng 242 the inf an t’s childho o d. Gr oup identity w a s include d in the mo d e l t o ac co un t f or an y group 243 diff erences . Ag ain, mother ide nt ity as w el l as b i r th y ea r of the inf ant w ere i nclude d a s r a ndom 244 eff ec ts. 245 T o test whet her t he in terbir t h in ter v al w as aff e c ted b y t he pre vious bir th, w e fit ted a similar 246 bino mial generalize d linea r mi xed mo del wi th binary rep r oduc t io n ( r eproduced ne xt ma tin g 247 s e a s o n y e s / n o ) a s o u r r e s p o n s e v a r i a b l e . A s f i x e d p r e d i c t o r s w e u s e d th e s e x o f th e i n f a n t a n d 248 ma t er nal r a nk and age, a s w ell a s the group identity . Here ag a in, mo ther i de ntity a s w e ll as bir th 249 y ea r of the inf ant w ere use d a s r andom e ff ects. 250 F or the si x behaviour a l re spons e s meas uring mat er n a l in v estment a nd offspr ing socia l 251 eng a gemen t, w e model led the nu mbe r of s uccess e s out o f t h e nu mber of tria ls us ing a bet a-252 bino mial ge ner al ized linear mix ed model, to acc om m oda te o v erdi spe r sion in proport ional dat a, 253 or us ed the abo v e-men tio ned Gam ma distributi on f or ma t er nal distance t o adul t group 254 mem ber s. Thes e models inc luded onl y t he 222 offsp r ing that s urvi v ed f or at leas t one yea r , a s 255 w e w a n te d t o a v o i d n o n - f u l l y e a r s o f d a ta c o l l e c ti o n . O f f s p r i n g o f w h i c h t h e m o t h e r d i e d d u r i n g 256 child ho od wer e not considered f or the mo t her in v estment models af t e r the m ot her ’s dea t h ( but 257 w ere c onside red f or t he gr oup e ng age me n t mode ls ). A ll s ix models shared the s ame fi x ed-eff e ct 258 str uctur e , w hic h incl uded the s e x of th e offs pring in a n int e r ac ti o n wit h the age of the inf a nt and 259 the r a nk and age of t he mo ther , e x c ept ma t erna l pro ximity t o ot her group m ember s, w hic h did 260 not incl ude offspr ing age (since onl y t he first y ea r of offspr ing w e re us ed). Gr oup identity w as 261 ag a in included to ac coun t f or group diff er e nces. W e included the offs pring ide ntity as a r a ndom 262 eff ec t t o acc oun t f or r e pea t ed me a sure s ( e x c ept f or mat ernal pro ximity t o adult grou p 263 mem ber s) and allo w ed m ot her iden tit y t o v ar y in both in t er c ept and offspr ing ag e slo p e 264 (mo the r identit y was inc luded a s a ra ndom ef f ec t wit ho u t the offspring a ge slope f or mat erna l 265 pr oximit y to adu l t group mem ber s ). W e allo wed t he dispersion pa r ame te r to vary ac ros s 266 obse rv a t ion y ea rs, t o ac co unt f or different le vels of obse rv ation effort , w h ere v e r the mo de l 267 allo wed c on v er gence ( f or an o v e r vie w of mode ls, s ee suppleme n ta ry mate ria ls T able S1) . W e 268 u s e d a b e ta - b i n o m i a l e r r o r s t r u c t u r e , w h i c h a c c o m m o d a te s e x tr a - b i n o m i a l v a r i a t i o n a n d 269 .CC-BY-NC 4.0 International licenseavailable under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprintthis version posted February 17, 2026. ; https://doi.org/10.64898/2026.02.16.705899doi: bioRxiv preprint pr ovided w ell-be hav ed r esidual s; in all f ina l m odels, di spe r sion tes ts ind icated eit her ac cept able 270 disper sio n or ( mild) unde r di sper s ion. 271 R esidua l diagnostic s w er e c onduct ed u s i ng DH A R M a (Hartig, 2 024 ) , incl udi ng simu lati on-base d 272 re sidual plo ts, t ests f or o v er di spe r sion and outlier t ests, with boo t s tr ap-bas ed c heck s wher e 273 appropriat e. The model t esting mo th e r’ s p ro ximity t o t he in f a nt showed unde r di spersio n, a ll 274 ot her mode ls beha v e d well. W e a ssess ed the sig n ific ance of fix e d e f f e cts usi ng T ype I I W ald χ ² 275 t ests obtained via ano v a ’s. F or mode ls with s ignificant or ma rg inall y non-signific ant 276 interact ions, we used e mmeans ( L ent h & Pias k ow s ki, 2017 ) to es tima t e se x-specific s lopes a nd 277 to t es t pa irwis e contrasts of tr ends betw ee n sons and daugh t er s . 278

279 O ut of 6 04 inf ants born betw ee n 2010-2025 , 125 could not be reliabl y se x ed bef or e 280 disa pp e a r a nc e. Ou t of t he 479 s e x ed i nf ants, 388 sur v i v ed f or at lea s t one y e ar , meaning tha t 281 appro ximat el y 64% of in f an ts survi v ed unti l o ne y ea r of age. Appr o ximat e l y 44% of se x e d 282 inf ant s wer e f emale. 308 inf ants survi v ed t o three y ea r s of ag e , gi v ing a s urvi val r a t e to 283 adul th ood of a r ound 51%. R eproducing f e males had an av e rage of 3.19 offspr ing in their 284 recorded lif etime, wit h a minimu m of 1 and a maximum of 10. The a v erage int er birth in t erv a l 285 w as 1.3 4 y ear s f or mot her s that ha d mor e t ha n o ne offsp ring . About ha l f of po t e ntial ly 286 repr oduc t i ve f emale s ( f e males abo v e t he age of 3 tha t repr oduc ed at lea st on ce in t he ir lif e ti me) 287 repr oduc ed eac h y e ar , w ith a mini m um o f 0% in 2024 and a ma ximu m of 7 7.4% in 2011 . These 288 demographic s um maries include all inf ants obs erv ed betw een 201 0-2025 . A na l y ses below use 289 v ar i able-s p e cific s ubsets be caus e (i) mat erna l r ank is a v aila ble fr om 2012 on w ard, ( ii) sur vi v a l 290 anal yses a re r est ric te d to co hor t s wit h 3 y ea r of f ol low- up, and ( iii ) p ro ximit y anal yse s use da t a 291 col l ected t hro ugh 2022 pr ior to protoc ol c hanges ( s ee Me th ods ). 292 (i) Sex r a t io at birth 293 Of the 3 30 s e x e d inf a nts fr om 98 mot h ers f or w hom ma terna l r ank c ould be r eliabl y c alcu la ted, 294 ~45% w e r e f emale. The pr o babili ty of a bir t h being da ugh ter i nc r e as ed significa ntl y wit h 295 ma ter nal age ( χ ² = 4 .796 , p = 0. 029; Figure S1) . In contr as t , mat erna l r ank and the nu m ber of 296 f ema le s pre se nt during the matin g seas on sho w ed no e videnc e of influe n cing o f fs pring se x 297 (r ank: χ ² = 0.018 , p = 0 . 8 94 ; nu m b e r o f fe m a l e s : χ ² = 0.202 , p = 0 . 6 5 3 ) . S e x - r a ti o a t b i r th d i d 298 not dif f er among groups (χ ² = 0 . 628 , p = 0 .890 ). 299 (ii) Offspring sur vi v al 300 The lik eli hoo d of s urvi val to adult h o o d tende d to inc r ease wit h ma ter nal r ank ( χ ² = 7. 693, p = 301 0.006 ) . While the int er a ction bet w een ma t e rnal rank and offs pring s e x was n ons ignificant ( χ ² = 302 .CC-BY-NC 4.0 International licenseavailable under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprintthis version posted February 17, 2026. ; https://doi.org/10.64898/2026.02.16.705899doi: bioRxiv preprint 1.454 , p = 0.2 28), pos t-hoc t r ends indi cated t hat da ug h ters ’ sur vi v al incr eased significa ntl y wit h 303 ma ter nal rank (slope = 0 .646 ± 0 .2 32 SE, p = 0.0 05), w he r ea s s on s s how ed no eff ec t of 304 ma ter nal r ank ( slo p e = 0 .286 ± 0 .207 SE, p = 0 . 167; Figur e 1a). The diff erence b et w een t hese 305 slo p e s we r e how ev er not s i g nificant ( slope = 0 . 36 0 ± 0 .299 SE, p = 0.2 28) . Ma t e rnal loss 306 sig nif ic antl y dec r eased the lik e lih ood t o surv i v e t o adult ho od as w ell ( χ ² = 1 9.984 , p < 0.0 001) , 307 wit h ag a in no s ignificant diff erence be tween sons and d augh t er s ( χ ² = 0 .181 , p = 0 . 6 7 1 ) . P o s t-308 hoc c o mparis ons s how ed that in de ed bo th s ons and daug ht e rs we r e le s s lik el y t o surv i v e aft er 309 m a t e r n a l l o s s , a l th o u g h th e e f f e c t a p p e a r e d n u m e r i c a l l y s tr o n g e r i n s o n s ( s o n s : s l o p e = - 1 . 5 1 ± 310 0.409 SE, p = 0.0 002; daughter s: slope = -1.26 ± 0.4 45 SE, p = 0 . 0 0 4 6 ; F i g u r e 1 c ) , w h i l e n o t 311 being s tatisticall y diff e r ent fro m each othe r . Mat erna l age, off s pring s e x its elf and g roup identit y 312 sho w ed no signific ant e ff ects on offspring sur vi v al (mat er nal age: χ ² = 0.0 05, p = 0 .946; inf ant 313 sex: χ ² = 0. 00 4, p = 0 .951; group: χ ² = 5 . 00 5, p = 0. 1 71; Figure 1b) . 314 315 Figur e 1: Pr edi ct o rs of o f fsp rin g s ur viv al t o a d ul t h oo d ( a g e 3 ) by of fsp rin g s ex . Mo de l- pre di c te d p r ob a bi l ity 316 o f s u r v i v i n g t o a d u l t h o o d ( a g e 3 ) , s ho w n s e p a r a t e l y f o r s o n s ( b l u e ) a n d d a u g ht e r s ( r e d ) . S o l i d l i n e s s ho w 317 pr ed ict ed pr ob ab ilit i e s a nd shade d r ib bo ns i nd ica t e 95% C I s; po int s s h o w o b s er v ed s u r vi v al o u tc o mes 318 (0/1 , jit t er ed; r a w da ta p oi n ts) . P oi n ts a nd err or bar s i n (c ) sho w pr e dict ed m e ans ± 95 % CI. ( a ) Ma ter n al 319 domi n a nce r a n k (sc aled Elo sc or e ) : s ur vi v a l i nc r eas e d w it h m at er n al r a n k o v er al l, a nd pos t- hoc tr en ds 320 i ndic at e d t hat da ught ers ’ s u r v i v al i nc r e a s ed s ign ific a ntl y w it h r a n k , w he r eas so ns s h ow ed n o cl e a r r a n k 321 eff e c t . ( b) M at er n al a g e at birt h ( scal ed ) : no e vid e nce t h at m a t e r n a l a ge pr edic t ed s urv i v al f o r either s e x . 322 .CC-BY-NC 4.0 International licenseavailable under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprintthis version posted February 17, 2026. ; https://doi.org/10.64898/2026.02.16.705899doi: bioRxiv preprint ( c) Ma te r na l l o ss (O rp hane d ? F AL S E/ TRUE ): o f fsp r ing s u rvi va l wa s s t r ong l y r e du c ed b y ma te rna l dea th 323 duri n g childh ood f o r b ot h s e x e s ; pos t- ho c tr e n ds su gges t ed a s t eep er r e duc t ion i n s o ns, but t h e se x 324 diff e r enc e i n t he orph an i ng eff ect w as n ot s ig n ifi c ant . 325 (iii-a) R eproducti v e pa ce 326 Mo t her s w er e ma rginall y more lik el y to rep r o d uc e ag ain the f ol l owing breeding se a son aft er 327 gi ving birt h to daug h ter s t han to s ons ( χ ² = 2 .862 , p = 0 .091; Fig ur e S 2 ). M ate rnal r ank, age a nd 328 group ide nt ity did not aff ec t t he pr oba bility of a mot her rep r oduc ing ag ain the ne xt br eeding 329 se a son (r ank: χ ² = 2 .083 , p =0 . 14 9; age: χ ² = 1.392 , p = 0 . 2 3 8 ; g r o u p : χ ² = 6.050 , p = 0. 1 09; 330 Figure S2). 331 (iii-b) Mat er nal pr oximity t o o ffspr in g 332 Ma ter nal r ank sho w ed a significa ntl y diff erent e ff ec t on s ons and d augh ter s ( χ ² = 3 .922 , p = 333 0.048 ) , w here pr oximit y to sons tende d to inc r ea se wit h ma ter nal r a nk (sl ope = 0 .118 ± 0 . 06 9 334 SE, p = 0.0 86 ) , w hereas p ro ximit y to daugh ter s t e nded to decrease, th oug h not signific an tly 335 (s lope = −0 . 059 ± 0.07 5 SE, p = 0 .429; Figure 2a ). T he se s e x-spec if ic slope s diff er e d 336 s i g n i f i c a n tl y f r o m o n e a n o th e r ( c o n tr a s t = − 0 . 1 7 7 ± 0 . 0 8 9 S E , p = 0 .048 ) . Ma ter nal age ha d a 337 sig nif ic ant o v erall eff ect on mo ther -of fspring pro ximity ( χ ² = 8 .897 , p = 0. 003) . Alth oug h the 338 int eraction be tw een o ffs pring sex and ma t er nal age did not r e ach co n v entional signific ance ( χ ² 339 = 3.2 18, p = 0 .073 ) , pos t -hoc a nal y se s show e d tha t pr o x i mity to sons inc rea s ed significa nt ly 340 with ma t ernal age ( slope = 0 .224 ± 0.065 SE, p = 0 .000 5) , w he r eas pr o xi mity to da ugh t ers 341 sho w ed n o s ignificant r ela t ions hip w i th ma t er nal a ge ( sl ope = 0. 07 5 ± 0.0 68 SE, p = 0 . 269; 342 Figure 2b). The diff er e nce be t ween the se slopes w a s mar ginal ( contr as t = −0 . 148 ± 0. 083 SE, p 343 = 0 .073 ) . Mo the rs ’ s patial asso ciation wit h offspr ing w as not aff ect ed b y of fspring ag e ( χ ² = 344 0.033 , p = 0.85 6; Figu r e 2c), and ther e w as no e videnc e that pro ximity t o t he mo t her d iff e r ed b y 345 offspr ing sex ( χ ² = 1.78 3, p = 0 . 1 8 2 ) . P r o x i m i ty to t he m ot h e r v a r i e d a m o n g g r o u p s ( χ ² = 9.82 8, 346 p = 0 . 0 2 0 ) , w i th m o th e r s i n B D g r o u p g e n e r a l l y m a i n ta i n i n g l o w e r p r o x i m i t y t o t h e i r o f f s p r i n g 347 than K B and N H gro up (BD – KB: slope = -0 .500 ± 0 .194 S E, p = 0 . 048 ; B D – N H : slope = - 0. 37 0 348 ± 0.14 3 S E , p = 0 .047; Figure 6a ) . N one of the o t her groups diff ered fr om ea ch o ther . Random -349 eff ec ts es tima t es re v ealed s ubstantial a mong- m othe r va riation in base line pro ximity and in 350 offspr ing age - related slopes , as w ell as a dd it ional v ar iance a tt r ibu ta b le to t he offs pring ID . 351 .CC-BY-NC 4.0 International licenseavailable under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprintthis version posted February 17, 2026. ; https://doi.org/10.64898/2026.02.16.705899doi: bioRxiv preprint 352 Fi gur e 2: Ma t er na l pr o xi mit y t o o f fs p rin g a c r o s s mat er nal r a n k , ma te rn al a ge, an d of fs pri n g age. Eff ects o f 353 m a t er n al an d off spri n g ch a r a c t er istic s o n t h e pr o b a b ili t y t hat off spr in g w er e o bs e r v e d wit hi n 5 m o f t h e ir 354 mo ther , s ho wn s ep ar at e l y f o r s o ns ( blu e) a n d da ugh t ers ( r ed) . P oi n ts r e pr es e nt i nd i v idu a l off spr i ng- y ear 355 o b s e r v at i o n s (j i t t er ed ; r a w d a t a p o i n t s ) ; l i n es a n d s ha d ed r i b b o ns s ho w m o d el p r e d i c t i o n s ± 9 5 % CI , a n d 356 lar ge p oi nt s with err or bar s ( c) i ndic a te pr e d ic t e d m ea ns ± 95 % CI . ( a ) Ma t er n al do mi na nc e r a n k ( scal ed 357 Elo scor e ) : r an k s how ed a s e x -s pec ific eff e c t (si g ni fic a nt i n t e r a c ti o n ) , w ith pr o xi mi t y t endi n g to i nc r e a s e 358 w i t h r a n k f o r s o n s b u t t e n d i n g t o d e c r e a s e f o r d a u g h t e r s ( s l o p e s d i f f e r e d s i g n i f i c a n t l y ) . ( b ) M a t e r n a l a g e 359 (s cale d) : p r o x i mit y s how e d a n o v er all pos i t i v e eff ect of m at e r n a l a ge, d r i v e n b y a s ig n i fic ant i nc r e a s e f or 360 s o n s a n d n o c l e a r r e l a t i o n s hi p f o r d a u g ht e r s ( s e x d i f f e r e n c e m a r g i n a l ) . ( c ) O f f s p r i n g a g e ( s c a l e d ) : 361 pr o x imi t y di d n ot chan g e w it h o f fs pri n g age . 362 (iii-c ) Ma t e rnal g r oomi ng of of fspring 363 Ov erall, sons r ec ei v ed more mater nal gr oomin g t han daug hte rs ( χ ² = 4. 16 3, p = 0 . 0 4 1 ; F i g u r e 364 3). Materna l r ank and mater nal age had no sig n ific ant main ef f ec ts ( rank: χ ² = 0. 10 4, p = 0 . 747 ; 365 mo ther a ge: χ ² = 1 .359 , p = 0.24 4; Figur e 3a, b ), a nd no int erac t ions with se x wer e s tatistically 366 sig nif ic ant (all int eractions : p > 0.2 5) . Mothe rs’ gr ooming i nv estment in thei r offsp r ing did not 367 sig nif ic antl y change wit h o ffspring age ( χ ² = 2 .526 , p = 0.112 ) , i r r es p ecti v e of offspr ing s e x. 368 W h i l e s l o p e s f o r b o t h i n f a n t s e x e s w e r e n o t s i g n i f i c a n t l y d i f f e r e n t ( χ ² = 2.56 0, p = 0 . 1 1 0 ; s l o p e 369 contrasts = 0. 112 ± 0 .070 SE, p = 0. 1 10), pos t-hoc trends s ugges ted t ha t m ate rnal in v e st ment 370 in offspring grooming increa s ed w ith s ons’ age (slope = 0.114 ± 0. 051 SE, p = 0 . 0 2 6 ) , w h i l e 371 .CC-BY-NC 4.0 International licenseavailable under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprintthis version posted February 17, 2026. ; https://doi.org/10.64898/2026.02.16.705899doi: bioRxiv preprint remaining flat f o r daugh t er s ( s lope = 0.002 ± 0.0 58 SE, p = 0 . 9 7 3 ; F i g u r e 3 c ) . G r o u p i d e n ti ty 372 did not aff ec t ma t ernal gr oo min g o f off spring ( χ ² = 3 .296 , p = 0 .348 ) . 373 374 F ig u re 3: Ma te rn a l g r oomi n g i nve st me nt towa r d o ff s pr i ng ac r o ss ma t er na l r a n k, ma t e rn a l a g e , a n d o ff s pr i n g 375 age . M at er n al gr o o mi n g i n v es t me n t ( pr o po r ti o nal gr o o mi ng dir e c t ed t o the of fsp ri ng) p lo tt ed a ga i nst 376 m a t e r n a l a n d o f f s p r i n g p r e d i c t o r s , s ho w n s e p a r a t e l y f o r s o n s ( b l u e ) a n d d a u g ht e r s ( r e d ) . P o i n t s 377 r epr es e nt i nd i vidu al o ffspr i n g- y e ar o bs er v at ion s ( j i tt e r ed ; r a w d at a poi nts ) ; li n e s a nd sha ded r i bbo ns 378 s ho w m o d e l p r e d i c t i o n s ± 9 5 % C I , a n d l a r g e p o i n t s w i t h e r r o r b a r s ( c ) i n d i c a t e p r e d i c t e d m e a n s ± 9 5 % 379 C I . A cro s s p a ne l s, mot he rs g r o ome d s on s m o r e t h an da ug hte r s o ve ra l l. (a ) Mate rna l do minan ce r ank 380 ( sc a l e d E l o s co r e ): no evi den ce t ha t r ank p r e di c te d ma te rna l g ro omin g in v e stme n t . ( b ) Mate r na l a ge 381 (s cale d) : no e vide nc e that m a t er n al ag e pr edic t ed m at er n al gr oo mi ng i n v e st m e nt. (c ) Of fspr i ng ag e 382 (s cale d) : gr o o mi ng i n v es tm e nt did no t sho w a s i gnif ic an t a ge tr e nd o v e r a ll , b ut post - h oc tr ends s u g g e s t e d 383 gr oo mi ng i nc r e a s e d w ith a ge f or so ns w hi l e r ema i ni n g fl at f o r da u g ht ers (se x -sp ecif ic s lop e d iff er e nce not 384 s i gni fi c an t ). A c ro ss pa ne l s, mo t he r s g roo me d son s mo re than d aug hte r s o v e r a l l (main sex e f f e c t ). 385 (iii-d) Mat er nal coa li t iona ry s upport 386 Mo t her s support e d their offs pring in conf licts in 3. 2% of conflic ts in w hic h the offspr ing w a s 387 in v ol ved. Mother s’ c oalitio nary support of t heir offspring w a s str ongly aff ect e d b y offspring age, 388 ma t er nal rank a n d mat erna l age (Figur e S3) . The p robabili ty tha t a mot h er suppor t e d her 389 offspr ing decr ea s ed with offspr ing age ( χ ² = 1 6. 5 39, p < 0. 0001 ) and mater nal age ( χ ² = 5. 596, 390 p = 0 . 0 1 8 ) b u t i n c r e a s e d w i t h m o t h e r s ’ r a n k ( χ ² = 18.1 43, p < 0 .0001 ), with no e videnc e tha t 391 .CC-BY-NC 4.0 International licenseavailable under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprintthis version posted February 17, 2026. ; https://doi.org/10.64898/2026.02.16.705899doi: bioRxiv preprint these patt erns diff er e d b y offsp r ing s e x . T he gr o up identit y and the offs pr ing s e x had no 392 sig nif ic ant ma in ef f e cts ( group: χ ² = 1.901 , p = 0. 593; o f fs p ring se x: χ ² = 0.042 , p = 0 . 8 3 8 ) . 393 In ter a ct ion terms be tween sex and offspring age , materna l a ge o r r ank we r e n o t s ignificant (a ll 394 χ ² ≤ 0. 336, all p ≥ 0 .562 ) , indic at ing broadl y similar pa tter ns f or bot h so n s a nd daughte rs. 395 Ho w e v er , po s t -hoc trends indicat ed that daugh t er s w ere les s lik e l y t o r e c ei ve their mothe r’s 396 suppor t with increa sing mot he r ag e ( s lope = -0. 303 ± 0 .138 SE, p = 0 . 0 2 8 ) , b u t n o t s o n s ( s l o p e 397 = -0.187 ± 0. 155 S E , p = 0 . 2 2 8 ) . T h e d i f f e r e n c e b e t w e e n th e s e s l o p e s w a s h o w e v e r n o t 398 sig nif ic ant (estima t e = 0 .116 ± 0. 2 00 S E, p = 0 .562 ) . 399 (iv- a) Offspr ing soc ial engagement 400 F ema le offs pring w ere more eng age d in both gr o o min g int eractions and conf licts than male 401 offspr ing ir re spec ti v e of age ( gr oomin g: χ ² = 4 4. 4 63, p < 0 . 0 0 0 1 ; a g o n i s ti c : χ ² = 11. 3 1 0, p = 402 0.0008; Figure 4 ). Mat er nal rank positi v e l y aff ec t e d gr ooming eng age men t with gr oup me mbers 403 o f o f f s p r i n g , r e g a r d l e s s o f s e x ( χ ² = 7. 223, p = 0 . 007; Figur e 4a), but not agonis t ic eng ag ement 404 ( χ ² = 0.576 , p = 0. 448; Fig ur e 4d ) . P os t -hoc t rends re v ealed that w hi le the int eraction bet w ee n 405 offspr ing se x and mat erna l r ank w as n ot signific ant f or grooming eng a ge men t ( χ ² = 0 .688, p = 406 0.407 ) , d augh t er s s how ed a s tr onger p ositi v e eff ect ( slope = 0.14 0 ± 0 .053 S E , p = 0 .009 ) tha n 407 sons ( s lope = 0.09 3 ± 0.04 9 SE, p = 0 . 0 5 8 ) . M a te r n a l r a n k d i d n o t a f f e c t a g o n i s ti c e n g a g e m e n t 408 o f th e s e x e s d i f f e r e n t l y ( χ ² = 0.356, p = 0.55 1) . Ma t e rnal age did not aff ec t grooming ( χ ² = 409 1.429 , p = 0 . 2 3 2 ) , n o r a g o n i s ti c e n g a g e m e n t o f o f f s p r i n g ( χ ² = 0. 00 4, p = 0 . 953; Figur e 4b, e) . 410 The in t eraction bet w ee n ma t ernal a ge and offs pring s e x w as not signific ant f or bot h behavio urs 411 as w e ll ( gr o oming: χ ² = 0.453, p = 0 .501; conflic ts : χ ² = 0.134, p = 0 . 7 14) . Po s t- h o c s l o p e s 412 confir med t hat ma terna l age did no t a ff ect sons or d a ughters diff er e ntly in bot h beha vio ur s. T he 413 eng a gemen t in bo th gr oomin g int er ac tions and conflicts increa s e d f or bo th sex e s with age 414 ( g r ooming: χ ² = 4 02.08 2, p < 0 . 0 0 0 1 ; c o n f l i c ts : χ ² = 369. 964, p < 0 .000 1; Figure 4c,f ) but 415 s h o w e d a s i g n i f i c a n t d i f f e r e n c e i n s l o p e s o f g r o o m i n g o v e r o f f s p r i n g a g e b y s e x ( χ ² = 5. 909, p = 416 0.015 ) . P ost-hoc t rends re v ealed a str onge r inc line f or da ugh t ers than f or s ons, w hile bo th sex es 417 sig nif ic antl y incline d in t he ir grooming with group mem ber s (sons: s lope = 0 .523 ± 0. 039 SE , p 418 < 0.00 01; da ughters : slope = 0. 640 ± 0. 037 SE, p < 0.00 01 ) . The int eraction betw e en o ffspring 419 age and se x w as not signific ant f or a g onistic eng ag emen t ( χ ² = 0 .979 , p = 0 .322 ). P os t-h oc 420 slo p e s confir med that age-rela t ed increases in c onflic t eng age ment w e r e si mila r f or sons a nd 421 daugh ter s. 422 Gr oup ide nt ity s tr ongl y aff ect ed o f fs pri ng e ng ageme nt with othe r group mem ber s ( gr o oming: χ ² 423 = 82 .377 , p < 0.0 001; conflic ts: χ ² = 106 .943 , p < 0. 0001 ) . P airwi s e compar isons r ev eale d 424 pr o nounced diff erences among grou ps, wit h offspr ing in B D sho wing s ubs ta n tial l y lo w er 425 eng a gemen t tha n th os e in AK, K B and N H in bo th beha vio ur s. Offspring in KB s how ed higher 426 .CC-BY-NC 4.0 International licenseavailable under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprintthis version posted February 17, 2026. ; https://doi.org/10.64898/2026.02.16.705899doi: bioRxiv preprint eng a gemen t than th ose in AK and NH i n both groo min g and conflic t s , w he r eas AK diff ered from 427 KB bu t no t f rom N H ( Figure 6c,d). 428 429 Fi gur e 4: Of fsp r i n g s o c ial e ng a g e ment wi th g r ou p me mb e rs a c r oss m ate rn al r an k , mat er nal a ge, a nd 430 o ffs pri n g ag e. Mod e l l e d o ff sp rin g enga ge men t r ate s in g ro o min g (a- c , t op row ) an d co n f li ct ( d -f , b ot tom 431 r o w ) , s ho w n s e p a r a t e l y f o r s o n s ( b l u e ) a n d d a u g ht e r s ( r e d ) . P o i n t s s ho w i n d i v i d u a l o f f s p r i n g - y e a r 432 o b s e r v at i o n s (j i t t er ed ; r a w d a t a p o i n t s ) ; l i n e s a n d s ha d ed r i b b o ns s ho w m o d el p r e d i c t i o n s ± 9 5 % CI , a n d 433 lar ge p oi nt s w i th err o r bar s (c, f ) i ndic a t e pr edic t ed me a ns ± 95% CI . Acr o s s p a n e ls , dau g h t e r s w e r e 434 mo r e enga ged than son s. ( a– c ) G r o o ming e nga gemen t : ( a ) Mate r na l d omin an ce r ank ( s ca l e d E l o s c o r e ): 435 gr oo mi ng en g age m ent i nc r e a s e d wit h m at er n al r a n k, w ith p ost -hoc tr e nd s i nd ica ti ng a c l e ar er pos it i v e 436 e f f e c t f o r d a u g ht e r s t ha n s o n s , a l t h o u g h t h e s e x × r a n k i n t e r a c t i o n w a s n o t s i g n i f i c a n t . ( b ) M a t e r n a l a g e 437 ( sc a l e d ) : g r o o min g e nga gemen t sho w e d no re l at ion s hi p wi t h ma te rn a l ag e. ( c) O ff sp r ing a ge ( sc a le d ) : 438 gr oo mi ng e n ga g e m ent i ncr e as ed str on gl y w i th offs pr i n g ag e i n bot h se x es , with a s t eep er i nc r e a s e in 439 .CC-BY-NC 4.0 International licenseavailable under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprintthis version posted February 17, 2026. ; https://doi.org/10.64898/2026.02.16.705899doi: bioRxiv preprint daug ht ers th a n so ns (s ign if ic ant s e x × age i nt e r a c ti o n). (d –f ) Co nf l ic t en g a ge m ent: (d) Mat er n al 440 domi n a nce r a n k ( sc a l ed E l o s cor e): co nfl ict e n ga gem e nt s how ed n o r e la ti o nship wit h m at er nal r a n k. ( e) 441 M a t er n al ag e (s cal e d): c o n flic t en g a g e m en t s ho w ed n o r el a t ions h ip w it h ma t er n al age. ( f ) Offs pri n g ag e 442 (s cale d) : c o nflic t en g age m ent i ncr eas ed st r o n gl y wit h o ff s pri n g a g e f or b oth se x e s, with n o s e x diff er enc e 443 i n the ag e-r el at ed slop e, a l tho u g h d a u gh t er s w e r e mo r e e n gaged on a v er a ge. 444 (iv- b) Expos ur e t o ot her g r oup mem be rs 445 Mo t her s diff er e d c onsi s t e nt ly in how close l y the y positioned themse l v es r elati ve t o the nea r es t 446 adul t during t he i nf a nt ’ s fi rs t y e ar , with s ubstantial amon g- mo t her v a r i a t io n in ba s eline spacing 447 (r andom int er c ept v a rianc e = 0.0 55, SD = 0. 2 35) . Ther e w as no e v idenc e tha t offs pring se x 448 pr e dict ed mea n distance t o t he nearest adult ( χ ² = 0.488 , p = 0.48 5) . Materna l dominance r ank, 449 howev er , showed a marg in a l positi v e o v e r all a s soc iation wi th s pacing ( χ ² = 3 . 277 , p = 0 . 0 7 0 ) . 450 This eff ect did no t diff e r b y offs pring se x ( χ ² = 0 .287 , p = 0. 592 ) . P ost-h oc t rend estimat es 451 indicate d t hat dist ance tended to decrease w ith rank f o r mot he rs of son s ( s lope = −0.088 ± 452 0.050 SE, p = 0 . 0 8 0 ) , w h er e a s n o s i gn i f i c a n t r el a ti on s h i p w as d e t e ct e d f o r m oth e rs o f d au g ht e r s 453 (s lope = −0.0 53 ± 0.05 3 SE, p = 0. 3 17; Figure 5a ). The diff erence betw e e n thes e slope s w a s 454 howev er not sig nificant (c ont ras t = −0.035 ± 0 .066 SE, p = 0 . 5 9 2 ) . M a te r n a l a g e h a d a s t r o n g 455 o v e r all incre as ing e f f e ct on spa cing beha viour ( χ ² = 29.1 66, p < 0.001 ), with ol d e r mothers 456 retaining low er p ro ximity to adul t neighb our s. The eff ect of ma t er nal ag e dep ended o n offsp ring 457 sex (χ ² = 5. 0 10, p = 0 . 0 2 5 ) . P o s t - h o c a n a l y s e s r e v e a l e d t h a t d i s ta n c e to th e n e a r e s t a d u l t 458 increa s ed s trongl y wit h mater nal a ge f o r mot her s of sons (slope = 0. 2 90 ± 0.0 51 SE, p < 459 0.0001 ) , w hereas the increa s e with ma t er nal age w as weak er f or mothe rs of daugh t er s (slope = 460 0.140 ± 0. 055 SE, p = 0. 011; Figure 5b ). These age-r e lated slo p e s diff ered signifi c ant l y bet w e en 461 mo t hers of s ons and daughter s (c ontr as t = 0.15 0 ± 0. 067 SE, p = 0 . 0 2 5 ) , i n d i c a t i n g th a t t h e 462 age - de pendent inc r e a s e in spa cing w a s mor e p ronounced w he n m ot her s w e r e caring f or s on s. 463 M e a n d i s ta n c e to t h e n e a r e s t a d u l t a l s o v a r i e d a m o n g s o c i a l g r o u p s ( χ ² = 1 1.338 , p = 0. 010 ), 464 wit h BD -gro up-mo t her s ha v in g smalle r distance t o their near est adult neigh bo ur than KB- a nd 465 ( m a r g i n a l l y ) N H - g r o u p - m o th e r s ( B D – K B : s l o p e = − 0 . 5 0 2 ± 0 . 1 6 9 S E , p = 0.016; B D – N H: 466 slo p e = − 0 .232 ± 0 . 0 99 SE, p = 0 .089; Figure 6b) . 467 .CC-BY-NC 4.0 International licenseavailable under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprintthis version posted February 17, 2026. ; https://doi.org/10.64898/2026.02.16.705899doi: bioRxiv preprint 468 F ig u re 5 : M ate rn a l ef fe ct s on p r o x i mit y t o a du lt g r ou p m emb e r s du ring th e o ff sp r ing ’s f i rs t y e ar . Ma tern a l 469 pr o x imi t y t o a dult gr oup me m be r s ( m; di st anc e t o the n ear est adult n ei ghb o ur) plott e d as a fu nct io n o f 470 m a t e r n a l c ha r a c t e r i s t i c s , s ho w n s e p a r a t e l y f o r m o t he r s o f s o n s ( b l u e ) a n d d a u g h t e r s ( r e d ) . S e m i -471 t r a n s p a r e n t p o i n t s s ho w i n d i v i d u a l o b s e r v a t i o n s ( j i t t e r e d ; r a w d a t a p o i n t s ) . L i n e s s h o w m o d e l 472 pr ed ictio n s w it h shaded 9 5% co nf ide nce i n t er v a ls . ( a ) Mat er n al r an k ( scal ed Elo s c or e) : dis ta nc e t o the 473 n ear es t a dult s h ow e d a m a r gi nal o v er all as soci at io n with r a n k, w it h pos t-hoc t r e nd s s ug gest i ng sl i gh tl y 474 sm all e r d is t anc es at h i gher r a n k f or m ot hers of s o ns a nd no c l ear r e l at io ns hip f or mo thers o f d aught ers ; 475 the r an k × o ffspr i n g s e x i nt er act io n w a s n ot s ign if ic an t . (b) M a t e r nal age (sc aled) : d i sta nc e to t he n e ar est 476 adu l t i nc r e a s e d s tr o n gl y wi th mat er n al a g e , and th i s eff ect w as s e x-d epe n den t ( si g n ific a n t i n t e r a c ti on) , 477 w ith a st e e p er age -r elat e d i ncr e as e f or m ot h e r s of s o ns t han f or mothers of d a u ght e r s . 478 .CC-BY-NC 4.0 International licenseavailable under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprintthis version posted February 17, 2026. ; https://doi.org/10.64898/2026.02.16.705899doi: bioRxiv preprint 479 Fi gur e 6: Gr o u p d i ff e r e nces in m o t her– o f fsp rin g p r oxi mit y , m a ter nal pr oxi mit y t o a d ul t g r o u p mem b e rs , a nd 480 o ffs pri n g so c ial e n g ag e m en t. G r o u p - l e v e l v a r i a t i o n a c r o s s t he f o u r s t u d y g r o u p s ( B D , K B , N H , A K ) . S e m i -481 tr a nsp ar e nt p oi n t s s ho w i nd i v idu a l offs pr i ng- y e a r o bs er v a t io ns (r a w dat a; j it t er ed; blu e = s o ns, r ed = 482 daug h t ers) . L ar g e gr e y po i nts w i th err or b ars s how pr e dict ed gr oup me a n s ± 95 % CI . ( a) Pr o b abil it y tha t 483 the o f fs pri n g w as o bs er v e d wi thi n 5 m of i t s mot her ; mot her - offs pri n g pr o xim it y d iff er ed a mo ng g r o up s 484 (o v e r a ll gr o up e ff ect) , w it h mo t h ers i n BD g en er all y sho w i n g lo w er pr o x i mit y to the ir o ffspr i n g than KB 485 a nd NH. ( b ) Mat er n al pr o xi mit y t o a d ult gr oup m e m b ers (m ; d ist a nc e to t he n e a r e s t adu lt n e i g hbour 486 duri n g the of fspr i ng ’s fir st y e ar); sp aci n g to t he n e ar est adul t d iff er ed amo ng gr oups ( o v er all gr o up 487 e f f e c t ) , w i t h B D m o t he r s m a i n t a i n i n g s m a l l e r d i s t a n c e s ( c l o s e r p r o x i m i t y ) t o a d u l t s t h a n K B ( a n d 488 m a r g i n all y NH) . (c ) O ffs pr i n g gr o omi n g e ng age m ent r a te (pr opor ti o n of gr ou p gr oo min g i n t er acti o ns 489 in v o l vin g t he fo ca l o ff sp r in g ) ; o f f s p r ing in B D sho w e d lo w e r g r o omin g eng age ment th a n o ff s p r i n g in t he 490 o t he r g r o u p s ( o v e r a l l g r o u p e f f e c t ) , a n d d a u g ht e r s w e r e m o r e e n g a g e d i n g r o o m i n g t ha n s o n s . ( d ) 491 .CC-BY-NC 4.0 International licenseavailable under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprintthis version posted February 17, 2026. ; https://doi.org/10.64898/2026.02.16.705899doi: bioRxiv preprint Off s p r i n g c onfl ic t en g ag eme n t r a t e (pr o porti o n of gr oup ago nis t ic i nt er acti o ns i n v o l v i ng the f o c al 492 offs pri n g); off spr i ng i n BD sho w ed l o w er confl ict en g ag e me n t tha n othe r g r oups (o v er all gr oup eff ect) , 493 an d da u ghte r s w e r e mo r e eng a ge d in c o n f l ict s t h an so ns. 494

495 Se x diff er enc e s in be ha viour and lif e-hi story trajec tories ar e wide sp read a c r o ss a nimals, yet the 496 mec hanisms thr o ug h w hic h m ot her s s hape these diff er e nce s remain po orl y under s t ood. Our 497 long - term d a ta sugg est cle ar s e x diff er ence s in how ver v e t o f fs pring dev elop, interact wit h t heir 498 mo t hers , and surv i v e t o adul th ood. T og ether , thes e findings indicat e that ma t e r nal in v es tment in 499 this sy st em diff e rs in f orm rather than in mag nit ude, a nd that ma t ernal effec ts a r e exp r essed 500 prima ril y thr oug h p o stnata l de v elopm e n tal pat h wa y s that shape offs pring social e xpo sur e a nd 501 eng a gemen t , rather t ha n thr oug h bia sed a llocati on at bir th al one. 502 W e ex amined how ma t e rnal character ist ic s ( age and dominanc e rank) s hape s e x alloca ti on, 503 offspr ing sur vi v al, mater n a l in v es tme n t , a nd offspring soc i a l e xpos ur e , an d h ow t hes e pr o ce sse s 504 diff er bet w een s ons and da ugh ters in a f emale - p hil opa tr ic pr imate. Spec ificall y , w e e x amine d (i) 505 w he t her off s pring sex r atios at birth v ar i ed with ma t er nal age and domina nce rank; (ii ) how 506 ma ter nal rank and maternal presenc e inf l ue nced offspring s urvi v a l to ad ul t ho od in sons a nd 507 daugh ter s; (iii) how materna l age an d r ank shaped pat terns of ma t e rnal in v est ment acros s 508 offspr ing de v elopmen t , including r epr oduc ti ve pa cing, spa tia l as soc iat io n, g r ooming , a nd 509 coa litio n a ry suppor t; a nd (i v ) w he the r se x diff erenc es in offspring s oc ial e x p o sur e a nd 510 eng a gemen t wit h group me m ber s wer e cons i stent wi t h t hese materna l in v es tme nt pat te rns. 511 Ma t er nal eff ec ts on offspr ing ope rat ed in dis t inc ti v e w ay s in o ur populati on. O ur r e s ults indica t e 512 th a t s o n s m a i n l y b e n e f i t f r o m th e d i r e c t p h y s i c a l p r e s e n c e o f th e i r m o t h e r , r e f l e c t e d i n t h e 513 pr o longed pro ximit y and incr e ased ma terna l groomi ng, w h ile being po t e ntia lly par tic ularly 514 vulnerable to ma t er nal loss . Daugh t ers, in contrast , s how ed patt erns consist ent wit h b enefiting 515 indir e ctl y fr om the ir mothe r’s rank, a nd t e nded t o eng ag e e arlier and more e xt ensi v el y with 516 ot her group member s. Altho ug h f or mal in f ant s e x and mater nal rank in te r ac tions w er e not 517 cons ist entl y s ignificant ac r o s s models , the es tima t ed r a n k - r elat ed e ff ects wer e r epea t edl y la r ge r 518 in daugh t er s than in sons . These pa t t e r ns a re co n sist ent wit h the idea tha t ma t erna l beha viour 519 ca n func ti o n a s r ol e-specific de v elopm ental prepa ration of bo th s e x es – i .e ., s ocia l sca f f o ldi ng – 520 rather than reflec tin g onl y ene rgetic bi as. 521 O ur r e sult tha t older mo ther s w er e mor e lik e l y t o produce daught er s, but n ot hig her -r anking 522 mo t hers , contrasts findings in cercopithecine pr imat es ( Maestr ipie ri , 200 2), bu t is in line with 523 w or k on ungula tes and ot her p rima te s, w here ma t e rnal age w a s a st ronger pr edictor of se x 524 alloc a tion a t birt h t han soc ial stat us ( Côté & Fes ta-B ia nche t, 2001; Lonsdor f, 2017) . T he se ag e-525 .CC-BY-NC 4.0 International licenseavailable under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprintthis version posted February 17, 2026. ; https://doi.org/10.64898/2026.02.16.705899doi: bioRxiv preprint related biases tow a r d s producing daugh ter s ar e co n s istent wit h m odels pr edict ing increas e d 526 in v es tment in the se x with the more predictable fitness ou t co me, w he n f ut ur e r ep roducti v e 527 oppor tunities dec line ( Leimar , 1 996 ); as w e ll as with indicati ons t hat da u g h t e rs rep r esent a 528 “saf er ” in v e stment for olde r f emales i n f emale-p hi lopa tric pr imat es (Brown , 20 01) . Alt ho ug h 529 loc al r e sour c e co mpetition a n d e nhanc eme n t mode ls (Cla rk, 19 78; Emle n et al., 1986 ) a r e of t en 530 disc us s ed in the c ont e xt of se x all ocation, our findings sugg est that in our popula t i on, these 531 p ro c e s s es ar e ex pr es se d pr i m a r i ly t h ro u g h p o s tn a ta l d eve l o p m e n ta l p a t hway s , r a th e r t h a n 532 thr o ug h biase d se x r atios at bi r t h. 533 More br o adl y , the pat t e rn t ha t daugh te r s a p pe a r to gain greater de v elopme nt al ad v ant age s from 534 ma t er nal rank i s cons i st ent wi th e vid enc e from verv ets a nd other pr imat es, w here mat erna l 535 rank i s di r e ctl y tr a n s mitt e d t o dau g h t e rs a nd s tr ongl y d e t ermines t he ir compe t i ti v e a nd 536 repr oduc ti ve suc cess (Horrocks & Hunte, 1 983; Ma est ripieri, 20 18; Meikle & V ess e y , 19 88). In 537 our da t a , r ank-relat ed eff ec ts on survi v al and s ocial engagement w ere di r e ctionall y s t ronger in 538 d a u g h t e r s , e v e n w h e n s ta ti s ti c a l t e s ts o f i n t e r a c ti o n s d i d n o t a l w a y s d e t e c t c l e a r s e x d i f f e r e n c e s . 539 This c on v e r gence ac ros s out co me s aligns with the loc a l r esource enha ncement the or y (Emle n et 540 al., 1 986 ), a ltho ug h e xpre s s ed de v elo p me nta ll y (pos tna ta ll y) rat her tha n thr oug h sex alloc at ion 541 (pren atall y ). A t the same time, son s b eing mor e de p endent o n the pre senc e of t he ir mot her i s 542 mirrored in findings in mac aques and other pr imat es, wher e ma le off s pring w e r e f ound to be 543 more sen s it i v e to ma ter nal loss and ea r l y-lif e ad v er s ity ( Meikle & V es se y , 198 8; P at ters on et al., 544 2024) . Other e vide nce of mo t her s po t entia ll y acti v e l y f a cili ta ting s ocia l int egration and 545 independenc e in the philopa t r ic se x come s from c himpanzee s, w here mot her s of so ns wer e 546 f o und t o s pend mor e ti me wit h ma les in t he fir st six months of t he ir son ’s lif e (M urra y et al., 547 2014) . While we did not find equa ll y s tr ong se x diff erences in all beha vioural doma ins, t he 548 reduced p ro ximity t o othe r group me mbers of o lder f emal es with sons w as a bsent w hen these 549 f ema le s ha d daugh ter s, indicat ing si milar pat ter ns. Since v e r v et s r e p r oduc e offspr ing ne a rl y 550 annual l y and offsprin g r ema in semi-de pende n t on their mo ther f or abou t t hr e e y ears ( mir ror e d 551 b y t h e e f f e c t o f m a te r n a l l o s s o n s u r v i v a l o f o f f s p r i n g t o t h r e e y e a r s ) , i t c a n b e e x p e c te d t h a t 552 these res ult s w o uld be less p ronounc e d in this spe cie s c ompar e d t o more s low e r-r e pr oduc i ng 553 spe cie s . N e ve rtheles s, the indication t hat daug h t e rs in our population eng a g ed more in socia l 554 int eractions w ith o the r group mem ber s, w herea s mot he rs maintained some what stronger dir ec t 555 groomin g in v es t me nt in s ons, point in the same direction. S uc h ear l y eng ag ement ma y pr e par e 556 daugh t er s f or lif elong r e sidence withi n the group ’s f ema le hie r arch y , w her eas son s , w ho w il l 557 disper se , ma y g ain less from ea rl y int eg r ation int o t he ma t e rnal s ocia l and ran k str uctur e . 558 These patt er ns o v erall do not indic a te reduce d mat er nal care t owar ds d a ugh t ers pe r s e , but 559 rather sug gest diff erences in how mot her s alloc at e in v estment acros s se xe s. Ma t e rnal age a nd 560 .CC-BY-NC 4.0 International licenseavailable under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprintthis version posted February 17, 2026. ; https://doi.org/10.64898/2026.02.16.705899doi: bioRxiv preprint rank appea r t o mod ula t e whet her in v estment is e xp re ssed thr oug h direct p r ot e cti on a nd c ar e 561 (in s ons ) or throug h indir ec t benefits media t e d b y s ocial status and netw o r k int eg r ations ( in 562 daugh ter s). This alig ns w ith Lonsdorf ’s (2017 ) fr a mew ork , whic h e mp hasize s tha t ma terna l 563 eff ec ts on off s pring fitness oft en a rise t hroug h opport unities f or socia l p o sit ioning r ather t h an 564 thr o ug h dif f er enc es in ca regi ving eff ort . 565 No t a bl y , our r esults diff er from sev er a l studies in other f emale-phi lopa tr i c pr ima t e s pecie s that 566 sho w st ronger mot he r-daugh ter bon ds a nd higher materna l in v es tme n t in da ugh ters ( e .g. , 567 Ishiz uka & Ino ue, 2023; K ulik et al., 2 016 ) . Inst ead, v erv et mothers i n our populatio n 568 maintained s tr onger s p a t ia l and grooming r elationships with sons . This sugge sts that s e x-biased 569 ma ter nal st rategies can be fle xible and ma y de pend on spe cie s - s pe cific soc ial d ynamic s, lev els of 570 agg r ession, or the d eg r ee to w hic h m a t e rnal pr esenc e p r o vides immediate pr o t e ct i v e benefit s. 571 In terbir t h in terv a ls we r e ma rg inall y s horter after t he bir t h of a daug h t e r , indicat ing low er 572 repr oduc t i ve cos t. W he t he r this potential low e r rep r oduc ti v e co s t comes fr om a re duce d 573 ma t er nal in ve stment , or w het her red uce d ma t er nal in ve stment fol lo w s as daug ht e rs a re les s 574 cos tl y , r e mains unc lear . H owe v er , it c a n be said that male verv ets hav e a po t entia ll y higher 575 repr oduc t i ve output t han f e males , sin ce rep roducti v e s k ew se ems t o be li m it e d in t his spe cie s 576 (M in k ner et al., 2018 ). In a se a sona l s y st em w he r e f ema le s a r e c ons trained in annua l 577 repr oduc t i ve outp ut and ma les ca n achiev e highl y v aria ble rep r oduc ti v e su ccess , mat erna l 578 i n v e stm e n t m a y b e s h a p e d l es s b y e n e r g e ti c ‘ c o st ’ a n d m o r e b y th e d i f f e r e n ti a l su r v i v al r i sk s an d 579 soc ial t rajector ies o f sons v e rsus daughter s. 580 So me c ont rasting group di ff erenc es w ere f ound in o ur pro ximity da t a as w ell: w hi le mo thers 581 remained gene rall y c loser to ot her a d ul t group mem ber s in BD compared t o KB a nd NH , t hey 582 remained fur the r from t heir offs pring i n this group. Suc h pat terns a r e cons i stent wit h pre viously 583 d o c u m e n t e d g r o u p d i f f e r e n c e s i n s o c i a l d y n a m i c s i n t h i s p o p u l a ti o n , w h i c h p e r s i s ts d e s p i t e 584 broadl y similar e cologic al conditi ons and demographic compos ition. Long- t e rm data from t he 585 s a m e s tu d y s i t e i n d i c a t e t h a t g r o u p s d i f f e r i n th e i r o v e r a l l l e v e l s o f a f f i l i a ti o n , l i k e l y r e f l e c ti n g 586 group s ocial sty les rather than sh or t - t er m demog r aphic eff ec ts ( K e rj e an et al., 20 24) . 587 Exper imental w ork on c o- f e eding t o le r a n c e further supports the idea that groups ca n diff er in 588 how c losel y indi vidua ls tolerate pr o ximit y to o t hers , par tic ularly in c onte xt s in v olving mot hers 589 and inf ants ( O preni et al. , 20 25). Since offspring e ng ageme nt was low e r in B D than in al l ot her 590 groups, mot her s might f ee l saf er t o a ll ow in f a n t s t o range further w hile r ema ining ne ar other 591 adul ts. Altho ug h g r oup size co uld co n tr ibu t e t o the se g r ou p diff erences , the patt erns do not 592 align wit h what w e w o uld expect if gr oup s ize w e re the p rimar y dr i v er . Spe cific all y , g i v en that 593 BD i s cons i stent l y t he la rges t gr o up an d KB the smal les t , a g roup-size e xplanatio n wou ld pr e di c t 594 a cons i stent ordering acr oss ou tco me s ( B D > N H > A K > KB). How e v e r , th e obse r v e d g roup 595 .CC-BY-NC 4.0 International licenseavailable under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprintthis version posted February 17, 2026. ; https://doi.org/10.64898/2026.02.16.705899doi: bioRxiv preprint diff erences do not f o l low this or de ring a cr oss me asure s . This s ugges t s that th e group diff erences 596 obs erv ed here lik el y r efle ct ba ckground va riation in group- le v el so cial struc ture, r a t he r t h an 597 group s ize pe r s e . T o gether , t he se fin d ing s sugge st that the group diff erence s obse r v ed her e 598 lik el y reflec t bac kgr ound v ar i ation in group-le v el s ocial str uctur e, rather than mat erna l 599 strat egies o r g r ou p sizes. 600 This s t ud y le v e r age s long-ter m o bser v at ional da ta , bu t se ver al limita tions shou ld be cons i de r ed. 601 Beca use demog r aphic , r ank, and beha v i o ur al mea sures w e r e not a vailable unif or m l y acros s t he 602 fu ll pr oje c t, anal yses rel y on v ariable - specific t ime wi ndow s and par t iall y o v e rlapping s amples, 603 w hic h c o mpl i c ates cross -outc ome co mpar isons. Me asure s of ma ternal in v es tme nt (pro ximit y , 604 groomin g, c oaliti onar y suppor t) c aptur e importan t co mpone nts of c ar e but d o no t incl ude 605 ener getic in v estmen t or ph y s iologica l mea sur e s , and co alitionary s upp o rt in par ticular is r ar e , 606 w hic h li mits pow er to detec t s e x- sp e cific e ff ect s. B e ha vioural meas ur e s of in v es t ment ar e 607 conditio ned on observ ation opportu nities and , pa rtic ularl y f or ra re be ha viour s such as 608 coa litio n a ry suppor t , ma y ha v e limit ed pow er t o det ec t s e x-sp e cific moderation. Finall y , 609 alt ho ugh restr icting be ha v iour al a nal yses t o 2012-2022 minimi z es impa cts o f prot o co l cha nges, 610 v ar i ation in obs erv ation effort and y ea r- or g r oup-le v e l ecol o gical c ondi tio ns ma y still co ntr ibu t e 611 to patt er ns obs e rv ed in this single popu lati on. As in an y obs e rv ational stud y , unmea sur e d 612 en vironmental v aria t ion and ind i vidual c ondition c ou ld co n f o u n d associa t ions with mat erna l 613 rank and ag e , a n d int e r ac tion eff ects m a y be unde rpower ed e v en in a long- t erm dataset . 614 T oge the r , our findings indicat e that mo t her s p r epar e sons and daught er s f or dif f e r ent socia l 615 fu tur es . Sons r el y hea vil y on ma t e rnal pro ximit y , g r ooming a nd prot ec tion, ma king t h e m 616 po tent ia ll y e xt ra vulnerable to ma te rnal loss , w herea s daug hters dev elop soc ial independence 617 ear lie r and pot ential l y c apitalize on inherit ed rank a nd br oader s ocial c onnectio ns . These 618 d i v e r g e n t p a th w a y s a r i s e n o t f r o m s tr o n g s e x - b i a s e s i n m a te r n a l c a r e , b u t f r o m c o n s i s te n t 619 diff erences in how ma t e rnal a ge, rank a n d beha viour t r ans late in to de vel op m ent al opp or tu nit ies 620 f or son s a nd daught ers . B y jointl y e xa mining sex alloc ation at birth, offspr in g sur vi v al, mat erna l 621 behavio ur and socia l eng ag ement in m ul tip le groups bu t wi thi n t he s ame popula tion, o ur re sults 622 pr ovide an integr a ted view of how ma ter nal age, dominanc e r a nk a nd o f fs p r ing s e x inter a ct to 623 sha pe e a rl y lif e tr aje ct ories in a f emale-phi lopa tric pr imat e. Our s tud y hig hlig hts ho w s ub t le 624 de v e lopmen t al dif f er enc es ac cum ula te into t he se x - s p ecific lif e historie s character i st ic of man y 625 m a m m a l s a n d e m p h a s i z e s th e i m p o r ta n c e o f e a r l y s o c i a l e n v i r o n m e n ts i n s h a p i n g th e e v o l u ti o n 626 of s e x roles. 627

628 W e thank the ons it e mana gers , A lb ert D r ies c her , A rend v an Blerk , Mic hael H e nshal l, Sibonis o 629 Thela, Zonk e M bu t ho and al l t he f ie ld assi s tant s , Mast e r students, Ph D s tud ents and p o st docs 630 .CC-BY-NC 4.0 International licenseavailable under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprintthis version posted February 17, 2026. ; https://doi.org/10.64898/2026.02.16.705899doi: bioRxiv preprint w h o co lle c ted t he dat a o v er the s tudy per iod . W e a r e gr atef ul to t he van d e r W alt f a mil y for 631 gi ving us the permission t o c onduct t he stud y on their la nd. This p roject w as funded b y t he 632 S wis s National Sc ience F oundati on (P300P3_15118 7, 310 03A _159587 , PP00 P3_1706 24, 633 PP00 P3_ 198913 and CR S II -222818) al ong with Br anc o W eiss F ellowship–S oc iet y in Scie nce, t he 634 g r a n t ‘ P r o F e m m e s ’ o f t h e F a c u l ty o f B i o l o g y a n d M e d i c i n e , U n i v e r s i ty o f L a u s a n n e a n d b y t h e 635 Eur o p e an R esear c h Counci l under the European Union 's H or izon 2020 r ese a rch a n d inno vation 636 pr o gr amme f or the ER C ‘KN OWLEDG E MOVES’ starting g rant ( g r ant agr ee ment n o . 949379 ) 637 tha t als o suppor t ed J.T ., N . D . and E.v .d. W . during the time of anal y s ing and w ri ting. 638 F or the p u rpose of Open A c ce ss, a C C B Y public cop yr ight lic ense i s applied t o an y A uthor 639 Acc ept ed Manusc ript ( A AM) v e r sion arising fr om this submiss ion. 640 A I decla r a tion: AI w a s used during p r e paration of this manusc ript sole l y t o impr o v e r e a dability 641 o f th e t e x t a n d a s s i s t i n r e f i n i n g c o d i n g . A n y A I - g e n e r a t e d m a t e r i a l w a s m e ti c u l o u s l y r e v i e w e d , 642 edited a nd v e r ified b y the aut hors . All ide as, int e rpr et at ions a n d concl usions a r e fr om th e 643 aut hor s. The authors t a k e ful l respon s i bili ty f or t he acc ur ac y and or iginality of all con t en t . 644 Author Contr ibutions: J . A . T a n d E . v d W . co n c e i v e d o f th e p r e s e n t e d i d ea . N . D . o v er s a w c o n ti n u ou s 645 data collec ti on. J. A .T . conce p tua lized data a nal y si s a nd c ar r ie d o ut data cleaning and anal ytic 646 ca lcu lati ons. E . v dW . helped with t he int er pr etation of the resul t s . J.A .T . w rot e the drafts of t he 647 man us cript that w e r e edit ed and appro v ed b y all a uthor s. 648 649 C o mp e t i n g In te r e s t S t a te me n t : the a ut h or s de clare that t he y h a v e no competin g int erests. 650 651 D at a av ail ability a nd open acc ess : all r elev ant data and code ar e a v a ilable on OSF : 652 htt ps://os f.io/pekd j /o v er view? view_onl y=dc d9305 4c b4a47 44b6c81056 5b3e6e67. 653 654 Et hic s s ta t eme nt: D ata colle c tion a dhe r ed t o t he AS AB G uidelines ( Beha viour , 2018 ) and w a s 655 purel y observ a t iona l. A l l in di v iduals obs er ved in this stud y wer e habitua t ed to hu man pr e s ence 656 and there w ere no int eractions betw een hu ma ns and s t ud y subjec ts during t he stud y . N o pe r mit 657 is required f or observ ationa l resear ch on this spec i es co nd u c t ed on pri v at e la nd. N e verthele ss , 658 E z e m v e l o K Z N W i l d l i f e a n d th e v a n d e r W a l t f a m i l y , th e o w n e r s o f r e s e r v e w h e r e th e s tu d y w a s 659 conduc t ed, appro v ed the stud y and gr a nt e d permis sion. 660 661

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Inte rna ti o na l J o u r na l o f P r i ma to l o gy , 32 (2), 783 4 15 –42 9 . https: / / d oi .or g/1 0. 1 007 / s 1 0 764 -010 -9478- 3 784 785 .CC-BY-NC 4.0 International licenseavailable under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprintthis version posted February 17, 2026. ; https://doi.org/10.64898/2026.02.16.705899doi: bioRxiv preprint Appendix 786 Ta b l e S 1 : O v er v i ew o f s t a t is t ical mod els us ed i n t his s tud y . 787 T o pi c R esp ons e v a ri a bl e Err or distr i b u ti o n /li nk F ixed e f fec t s (pr edic t o r s) R a nd o m ef f ec t s N ot e s / d a t a s u bs e t ( i) Sex all oc at ion at bi r th O f f s p r i n g s ex at birth ( d a u g h ter vs son) Bin omia l / lo g it Mat e r n a l r an k + Ma t er na l a g e + N um b e r o f adul t f em ale s in g r ou p d uring the m a t i n g s e a s o n + G r o u p identity Mo ther identity (r ando m in te r ce p t) + Birth ye ar ( r an d o m in te r ce p t) Includ e s o nl y bir th s with kno w n off s p r i ng s ex an d m at e r n al ran k ava i l a b l e. ( i i) O ff sp ri ng su rv i val Su r v iv al to adu lth o od ( age 3 ) (yes /no ) Bin omia l / lo g it Of fs p r i ng se x × (Mate rn al rank + Maternal a g e + Matern a l loss du r i ng chi ld hood ) + Gr ou p identity Mo ther identity (r ando m in te r ce p t) + Birth ye ar ( r an d o m in te r ce p t) R e st ricte d to c ohorts w h e re surviv al ou tc o m e to a ge 3 w as known (bi r th s bef or e 2 023). (iii- a ) Re p ro d u c t iv e pa ce Re pr o ductio n in th e f oll o wing br e e d i ng s ea s o n (ye s/no; pr o xy f or sho r t in te rbi r th inter va l ) Bin omia l / lo g it Of fs p ring se x + Mat e r n a l r an k + Maternal age + G r oup identity Mo ther identity (r ando m in te r ce p t) + Birth ye ar ( r an d o m in te r ce p t) R espon s e cod e d as whethe r the m o ther r e pr o d uc e d t h e n e x t s e a s on ( b i na r y) . (iii- b ) Mat ern al in v e s t m e n t: pr o xi m it y t o of f s p r i n g Matern a l pr ox imity to offsprin g (pr o portio n o f sc ans where offsprin g w a s with in 5 m of moth e r) Be ta- bin omia l / lo g it Of fs p r i ng se x × ( O f f s p r i n g a g e + Mat e r n a l r an k + Maternal a g e) + G r ou p identity Mo ther identity (r ando m in t er ce pt + r ando m slo pe of o ffspring a g e) + Offsprin g identity (r ando m in te r ce p t) Beha viour al data 20 12 –20 2 2; on l y o ffspring su rvivin g ≥ 1 ye ar; models i n c l ud e r e pe a t e d annu a l m easures (offsprin g a g e 1 –3). Di s p e r sion m o delled a s a f unction of o bse rv atio n ye ar . .CC-BY-NC 4.0 International licenseavailable under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprintthis version posted February 17, 2026. ; https://doi.org/10.64898/2026.02.16.705899doi: bioRxiv preprint (ii i - c ) Mat ern al in v e s t m e n t: gr o o m i n g o f of f s p r i n g Matern a l g r ooming inv es tment (pr o portio n o f mo t h er ’ s g r ooming dir ec ted to o ffspring) Be ta- bin omia l / lo g it Of fs p r i ng se x × ( O f f s p r i n g a g e + Mat e r n a l r an k + Maternal a g e) + G r ou p identity Mo ther identity (r ando m in t er ce pt + r ando m slo pe of o ffspring a g e) + Offsprin g identity (r ando m in te r ce p t) Beha viour al data 20 12 –20 2 2; on l y o ffspring su rvivin g ≥1 ye ar; d is p ersion modelled as a fu nction of o bse rv atio n ye ar . (iii- d ) Mat ern al in v e s t m e n t: c oa l it io na ry s upp o rt Matern a l co al i t i o n a r y supp ort (pr o portio n o f o ffspring con flicts in whi c h m o ther s u ppo r ted o ffspring) Be ta- bin omia l / lo g it Of fs p r i ng se x × ( O f f s p r i n g a g e + Mat e r n a l r an k + Maternal a g e) + G r ou p identity Mo ther identity (r ando m in t er ce pt + r ando m slo pe of o ffspring a g e) + Offsprin g identity (r ando m in te r ce p t) Beha viour al data 201 2 –2022; trials re st r i c t ed t o o f f s p r i n g co nflicts (tria ls > 0). Co nsta n t disp e r sion ( n o obser va ti on- ye ar d ispe rsio n term). (i v- a .1) Of fspri n g soc i a l en ga ge m en t : gr oo m i n g Offsprin g g r ooming en ga ge me n t (pr o portio n o f gr o u p g r oo m i n g inter a ction s in vo l v ing th e foca l o ffspring) Be ta- bin omia l / lo g it Of fs p r i ng se x × ( O f f s p r i n g a g e + Mat e r n a l r an k + Maternal a g e) + G r ou p identity Mo ther identity (r ando m in t er ce pt + r ando m slo pe of o ffspring a g e) + Offsprin g identity (r ando m in te r ce p t) Beha viour al data 20 12 –20 2 2; on l y o ffspring su rvivin g ≥1 ye ar; d is p ersion modelled as a fu nction of o bse rv atio n ye ar . (i v- a .2) Of fspri n g soc i a l en ga ge m en t : ag o n isti c int er a c t ions Offsprin g co nflict en ga ge me n t (pr o portio n o f gr o up a goni s tic inter a ction s in vo l v ing th e foca l o ffspring) Be ta- bin omia l / lo g it Of fs p r i ng se x × ( O f f s p r i n g a g e + Mat e r n a l r an k + Maternal a g e) + G r ou p identity Mo ther identity (r ando m in t er ce pt + r ando m slo pe of o ffspring a g e) + Offsprin g identity (r ando m in te r ce p t) Beha viour al data 201 2 –2022; trials r estricte d to yea rs with r e co r ded c o nflicts (tria ls > 0); d ispe rsion modelled a s a f unction of o bse rv atio n ye ar . .CC-BY-NC 4.0 International licenseavailable under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprintthis version posted February 17, 2026. ; https://doi.org/10.64898/2026.02.16.705899doi: bioRxiv preprint (i v- b ) Of fspri n g soc i a l ex p o s u re : mat ern al pr o xi m it y t o ad ul t gr ou p me mb e r s Matern a l pr o xim i ty to adul t g r oup m embers (me an dista n ce to n e a r est adul t n e ighbo ur d uring offsprin g ’ s fir s t ye ar; m) G a mm a / lo g Of fs p r i ng se x × ( Ma t er n al ag e + Matern a l r ank ) + Gr ou p id e n tit y Mo ther identity (r ando m in te r ce p t) F irs t-ye ar me a s u r e o nl y (n o off s p r i ng -age term ). Dispersio n modelled as a fun c ti on of cale n dar ye ar . 788 Ta b l e S 2: Bi r th se x r at io mode l (binomi al G LM M; r es pon se = d augh ter ). 789 Pr e di c to r Estim at e S E z p S i g In te r c e pt -0. 393 0.29 6 -1. 3 26 0. 18 5 Mate rn al El o (s ca l e d) -0. 015 0.11 2 -0. 1 33 0. 89 4 Mate rn al a g e (s c al ed) 0. 25 7 0.11 8 2.19 0 0. 02 9 * No . f e males (s caled ) -0. 086 0.19 0 -0. 4 49 0. 65 3 Gr o u p: B D 0. 30 5 0.44 9 0.68 1 0. 49 6 Gr o u p: K B 0. 10 4 0 . 4 19 0 . 2 49 0 . 8 03 Gr o u p: N H 0. 26 6 0.35 1 0.75 7 0. 44 9 Mo de l d et a i l s: N =33 0; AI C = 46 7 .3; BI C= 50 1 .5; logL i k= −22 4.7. 790 R a ndom i n t e r ce p t s: M ot her (V ar = 2 . 548 e− 09 ; 98 le v e ls ) , y ear _f ( V a r =6 .473e −10 ; 14 l e vels) . 791 Ta b l e S 3 : S urvi v a l model ( binomia l GLM M; respon s e = surv i v ed_to _ adu lt ) . 792 T able S 3a: Fixe d p r e d i cto r ou t co me s. 793 Pr e di c to r Est i m a te S E z p S i g In te r c e pt 0.98 9 0.472 2. 09 5 0 . 0 36 * Mate rn al El o (s ca l e d) 0.28 6 0.207 1. 38 3 0 .16 7 Or ph an ed ( TR UE ) -1.507 0.409 - 3. 68 2 <0 . 00 1 ** * Mate rn al a g e (s c al ed) -0.241 0.228 - 0 . 2 90 .CC-BY-NC 4.0 International licenseavailable under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprintthis version posted February 17, 2026. ; https://doi.org/10.64898/2026.02.16.705899doi: bioRxiv preprint 1. 05 8 Outc ome: d au ghte r -0.146 0.429 - 0. 34 0 0. 7 3 4 Gr o u p: B D 0.07 2 0.41 4 0 . 1 73 0 . 8 62 Gr o u p: K B 1.19 4 0.618 1. 93 2 0 . 0 53 · Gr o u p: N H 0.49 8 0.445 1. 11 8 0 .26 4 E lo × outc ome ( da ugh te r ) 0.36 0 0.299 1. 20 6 0 . 2 28 Or ph an ed( TR UE ) × outc ome ( daug ht er ) 0.24 7 0.582 0. 42 5 0 .67 1 M a t e r n a l a g e × outc ome ( daug ht er ) 0.42 2 0.288 1. 46 5 0 . 1 43 Mo de l d et a i l s: N =30 4; AI C = 37 6 .9; BI C= 42 5 .3; logL i k= −17 5.5. 794 R a ndom i n t e r ce p t s: Mot her (V ar = 0 . 2214; 94 l e v els ), y e a r _f ( V a r =0.6 0 94 ; 12 le v els) . 795 T able S 3b: S impl e sl opes of m a t er n al Elo b y o utco m e 796 Ou tco me Elo s lope S E z p so n 0.286 0.20 7 1.383 0. 16 66 d a ughte r 0.646 0.23 2 2.786 0. 00 53 Ta b l e S 3 c : Simpl e s lop es of m at er n a l age b y o utco m e 797 O utc ome Ma te rn a l a ge s lo pe SE z p so n − 0.241 0.228 −1.058 0.2 9 00 d a ughte r 0.181 0.211 0. 85 8 0.3 9 07 Ta b l e S 3 d : o rpha ni ng co ntr as ts w it h i n outc o m e ( e mm e ans ; C o ntr asts a r e o n the l o g- o dd s r at io s c al e ; 798 TR UE − F A L SE) . 799 Outc ome C ont ra s t ( TR UE − F AL SE ) E s t i ma te S E z p so n orpha n e d T R UE − F A LSE −1.51 0. 40 9 − 3.682 0 .00 02 d a ughte r orpha n e d T R UE − F A LSE −1. 26 0. 44 5 − 2.833 0 .00 46 .CC-BY-NC 4.0 International licenseavailable under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprintthis version posted February 17, 2026. ; https://doi.org/10.64898/2026.02.16.705899doi: bioRxiv preprint Ta b l e S 4 : Pr oximity model (be t a bino mia l GLM M; r es pons e = cbind(succ es s e s, 800 trials −suc ces ses) ) . 801 T able S 4a: F i x ed pr ed ict o r ou tc o m es . 802 Pr e di c t o r Es tima te S E z p S i g In te r c e pt - 1 . 882 0.14 0 -13 . 451 <0.001 * ** Outc ome: d au ghte r -0 .0 9 8 0 . 0 91 - 1 .0 6 9 0 . 2 85 A ge (c e nt ered ; ye a r s) - 0 . 000 0.07 2 -0. 0 05 0 . 9 96 Mate rn al El o (s ca l e d) 0.11 8 0.06 9 1.7 1 7 0 .08 6 · Mate rn al a g e (s c al ed) 0.22 4 0.06 5 3 . 4 63 <0.001 * ** Gr o u p: B D -0 .1 9 0 0 . 1 60 - 1 .1 8 7 0 . 2 35 Gr o u p: K B 0.31 0 0.21 6 1.4 3 4 0 . 1 52 Gr o u p: N H 0.18 0 0.16 9 1.0 6 5 0 .28 7 Ou tco me ( dau g ht e r ) × age - 0 . 027 0.08 5 -0. 3 17 0 . 7 51 Ou tco me ( dau g ht e r ) × E l o -0 .1 7 7 0 . 0 89 - 1 .9 8 0 0 . 0 48 * Ou tco me ( dau g ht e r ) × mat er na l ag e - 0 . 148 0.08 3 -1. 7 9 4 0 . 0 73 · Mo de l d et a i l s: N =50 4; AI C = 42 53 .3; BI C = 4 3 58. 8; lo gL i k = −2 101.6 . 803 R a ndom e ff ects : Mot her (I n t er c e pt V a r =0. 09 08; age V ar = 0. 0 700 ; 81 le v e ls ) , C od e ( I n t e r cept V ar =0 . 19 79; 804 222 l e v els) . 805 Dis pers io n mod e l : ~ as .f ac t o r (o bs_ y e a r ) . 806 T able S 4b: Sim p l e s lo p e s o f a ge b y o ut come. 807 O utc ome A ge sl op e SE z p so n − 0.0003 6 2 0. 07 17 − 0.005 0. 99 60 d a ughte r − 0.0271 6 2 0. 08 01 − 0.339 0. 73 45 T rend c o nt r a s t (so n − d aug ht er ) : e sti m a t e = 0.0 26 8 , S E = 0 .0846, z = 0 .3 1 7, p = 0 .75 1 5 808 Ta b l e S 4 c : Simpl e s lop es of m at er n a l Elo b y outc om e . 809 Ou tco me Elo s lope S E z p so n 0.118 0.06 87 1 . 7 17 0.0860 d a ughte r − 0.059 0.07 47 − 0 . 790 0.4293 T rend c o nt r a s t (so n − d aug ht er ) : e sti m a t e = 0.1 77 , SE = 0 .0894, z = 1 .98 0 , p = 0 .047 6 810 .CC-BY-NC 4.0 International licenseavailable under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprintthis version posted February 17, 2026. ; https://doi.org/10.64898/2026.02.16.705899doi: bioRxiv preprint Ta b l e S 4 d : S i mpl e slo pes of mat er n al ag e b y o utco m e . 811 O utc ome Ma te rn a l a ge s lo pe SE z p so n 0.2236 0.0646 3 . 4 63 0.00 0 5 d a ughte r 0.0752 0.0680 1 .10 6 0.26 8 8 T rend c o nt r a s t (so n − d aug ht er ) : e sti m a t e = 0.1 48 , SE = 0 .0827, z = 1 .79 4 , p = 0 .072 8 812 T able S 4e: Gr o up p air w is e co ntr asts ( emm e ans ; Co n tr as ts ar e o n t he log - odd s r a t i o sc ale; T u k e y - a d jus t ed 813 p- v a lu es) 814 Co nt r a s t Est i m a te S E z p AK − B D 0.19 0 . 1 60 1. 18 7 0. 63 50 AK − K B −0 . 3 1 0 . 2 16 − 1 .4 3 4 0 . 4 77 9 AK − N H −0 . 1 8 0 . 1 69 −1.06 5 0. 71 06 BD − K B −0 . 5 0 0 . 1 9 4 −2. 58 3 0. 04 82 BD − N H −0 . 3 7 0 . 1 43 −2.59 5 0. 04 66 KB − N H 0.13 0.1 9 4 0. 66 8 0. 90 91 Ta b l e S 5 : Ma te rnal g r ooming m odel (be t a bino mia l GLM M; r e sponse = c bind( succe sses, 815 trials −suc ces ses) ) . 816 T able S 5a: F i x ed pr ed ict o r ou tc o m es . 817 Pr e di c t o r Es tima te S E z p S i g In te r c e pt - 1 . 537 0.11 6 -13 . 256 <0.001 * ** Outc ome: d au ghte r -0 .1 7 8 0 . 0 79 - 2 .2 4 8 0 . 0 25 * A ge (c e nt ered ; ye a r s) 0.11 4 0.05 1 2 . 2 20 0 . 0 26 * Mate rn al El o (s ca l e d) -0 .0 1 1 0 . 0 61 - 0 .1 8 6 0 . 8 52 Mate rn al a g e (s c al ed) 0.02 8 0.05 7 0 . 4 83 0 . 6 29 Gr o u p: B D 0.06 7 0.13 5 0.4 9 7 0 .61 9 Gr o u p: K B 0.08 1 0.18 1 0 . 4 46 0 . 6 55 Gr o u p: N H 0.23 9 0.14 4 1.6 5 7 0 .09 8 · Ou tco me ( dau g ht e r ) × age - 0 . 112 0.07 0 -1. 6 00 0 . 1 10 .CC-BY-NC 4.0 International licenseavailable under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprintthis version posted February 17, 2026. ; https://doi.org/10.64898/2026.02.16.705899doi: bioRxiv preprint Ou tco me ( dau g ht e r ) × E l o - 0 . 010 0.07 8 -0. 1 33 0 .89 4 Ou tco me ( dau g ht e r ) × mat er na l ag e 0.04 2 0.07 2 0 . 5 73 0 . 5 67 Mo de l d et a i l s: N =50 4; AI C = 34 15 .2; BI C = 3 5 20. 8; lo gL i k = −1 682.6 . 818 R a ndom e ff ects : Mot her (I n t er c e pt V a r =0. 05 37; age V ar = 0. 0 235 ; 81 le v e ls ) , Cod e ( I n t e r cept V ar =0 . 13 10; 819 222 l e v els) . 820 Dis pers io n mod e l : ~ as .f ac t o r (o bs_ y e a r ) . 821 T able S 5b: Sim p l e s lo p e s o f a ge b y o ut come. 822 O utc ome A ge sl op e SE z p so n 0.11 4 0.0511 2. 22 0 0.02 64 d a ughte r 0.002 0.0581 0. 03 4 0.97 26 T rend c o nt r a s t (so n − d aug ht er ) : e sti m a t e = 0.1 12 , SE = 0 .0697, z = 1 .60 0 , p = 0 .109 6 823 Ta b l e S 5 c : Simpl e s lop es of m at er n a l Elo b y outc om e . 824 Ou tco me Elo s lope S E z p so n − 0.0113 0.06 07 − 0 . 186 0.8524 d a ughte r − 0.0217 0.06 54 − 0 . 331 0.7405 T rend c o nt r a s t (so n − d aug ht er ) : e sti m a t e = 0.0 10 4 , S E = 0 .0781, z = 0 .1 3 3, p = 0 .89 4 3 825 Ta b l e S 5 d : S i mpl e slo pes of mat er n al ag e b y o utco m e . 826 O utc ome Ma te rn a l a ge s lo pe SE z p so n 0.0277 0.0574 0 . 4 83 0.62 8 9 d a ughte r 0.0692 0.0546 1 .26 9 0.20 4 6 T rend c o nt r a s t (so n − d aug ht er ) : e sti m a t e = − 0 . 041 5, SE = 0.0724 , z = − 0 .5 7 3, p = 0 .5665 827 Ta b l e S 6 : Coalitionar y s upport m odel ( betabin omia l GL M M; ; res ponse = cbind(s ucc e s s es , 828 trials −suc ces ses; tria ls ≠ 0 ). 829 T able S 6a: F i x ed pr ed ict o r ou tc o m es . 830 Pr e di c t o r Es tima te S E z p S i g In te r c e pt - 3 . 975 0.28 4 -14 . 002 <0.001 * ** Outc ome: d au ghte r 0.02 8 0.19 4 0.1 4 4 0 . 8 85 A ge (c e nt ered ; ye a r s) - 0 . 482 0.15 7 -3. 0 61 0 . 0 02 ** .CC-BY-NC 4.0 International licenseavailable under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprintthis version posted February 17, 2026. ; https://doi.org/10.64898/2026.02.16.705899doi: bioRxiv preprint Mate rn al El o (s ca l e d) 0.48 2 0.13 9 3.4 6 9 <0.001 ** * Mate rn al a g e (s c al ed) - 0 . 187 0.15 5 -1. 2 07 0 . 2 28 Gr o u p: B D -0 .0 9 6 0 . 3 24 - 0 .2 9 6 0 . 7 67 Gr o u p: K B - 0 . 445 0.45 5 -0. 9 77 0 . 3 29 Gr o u p: N H 0.11 3 0.31 6 0.3 5 7 0 .72 1 Ou tco me ( dau g ht e r ) × age - 0 . 051 0.21 0 -0. 2 42 0 . 8 09 Ou tco me ( dau g ht e r ) × E l o 0.00 8 0.17 8 0.0 4 7 0 .96 3 Ou tco me ( dau g ht e r ) × mat er na l ag e - 0 . 116 0.20 0 -0. 5 79 0 . 5 62 Mo de l d et a i l s: N =44 9; AI C = 82 1 .5; BI C= 88 3 .1; logL i k= −39 5.8. 831 R a ndom e ff ects : Mot her (I n t er c e pt V a r =0. 28 27; age V ar = 0. 1 383 ; 80 le v e ls ) , Cod e ( I n t e r cept V ar =0 . 15 33; 832 212 l e v els) . 833 Dis pers io n mod e l : co n st a nt (dis pf or mul a ~ 1) ; r ep or t ed b et abi n o mi a l di sp ersi o n par a m e t e r = 137 . 834 T able S 6b: Sim p l e s lo p e s o f a ge b y o ut come. 835 O utc ome A ge sl op e SE z p so n − 0.482 0.157 −3.061 0.0022 d a ughte r − 0.533 0.168 −3. 170 0.0015 T rend c o nt r a s t (so n − d aug ht er ) : e sti m a t e = 0.0 50 8 , S E = 0 .210, z = 0 .24 2 , p = 0 .808 6 836 Ta b l e S 6 c : Simpl e s lop es of m at er n a l Elo b y outc om e . 837 Ou tco me Elo s lope S E z p so n 0.482 0.13 9 3.469 0. 00 05 d a ughte r 0.491 0.15 1 3.253 0. 00 11 T rend c o nt r a s t (so n − d aug ht er ) : e sti m a t e = − 0 . 008 33, SE = 0.178 , z = − 0 .0 4 7, p = 0 .9627 838 Ta b l e S 6 d : S i mpl e slo pes of mat er n al ag e b y o utco m e . 839 O utc ome Ma te rn a l a ge s lo pe SE z p so n − 0.187 0.155 −1.207 0.2 2 75 d a ughte r − 0.303 0.138 −2. 199 0.0 2 79 T rend c o nt r a s t (so n − d aug ht er ) : e sti m a t e = 0.1 16 , SE = 0 .200, z = 0. 579, p = 0 . 5623 840 Ta b l e S 7 : Grooming model (beta bino mi al GLM M; res pon se = cbind ( succ e sses , trials -succ es s e s ) ) . 841 .CC-BY-NC 4.0 International licenseavailable under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprintthis version posted February 17, 2026. ; https://doi.org/10.64898/2026.02.16.705899doi: bioRxiv preprint T able S 7a: F i x ed pr ed ict o r ou tc o m es . 842 Pr e di c t o r Es tima te S E z p S i g In te r c e pt - 3 . 503 0.09 3 -37 . 780 <0.001 * ** Outc ome: d au ghte r 0.35 6 0.05 9 6.0 2 0 <0.001 ** * A ge (c e nt ered ; ye a r s) 0.52 3 0.03 8 1 3 . 60 0 <0.001 * ** Mate rn al El o (s ca l e d) 0.09 2 0.04 9 1.8 9 0 0 .05 8 · Mate rn al a g e (s c al ed) - 0 . 062 0.04 7 -1. 3 20 0 . 1 87 Gr o u p: B D - 0 .598 0.11 2 -5.3 40 <0.001 ** * Gr o u p: K B 0.54 7 0.14 1 3 . 8 70 <0.001 * ** Gr o u p: N H -0 .1 8 9 0 . 1 16 - 1 .6 2 0 0 . 1 05 Ou tco me ( dau g ht e r ) × age 0.11 7 0.04 8 2 . 4 30 0 . 0 15 * Ou tco me ( dau g ht e r ) × E l o 0.04 8 0.05 8 0.8 3 0 0 .40 7 Ou tco me ( dau g ht e r ) × mat er na l ag e 0.03 8 0.05 7 0 . 6 70 0 . 5 01 Mo de l d et a i l s: N =52 4; AI C = 50 93 .5; BI C = 5 2 00. 0; lo gL i k = −2 521.7 . 843 R a ndom e ff ects : Mot her (I n t er c e pt V a r =0. 06 04; age V ar = 0. 0 0713; 81 l e v e ls ) , C od e ( I nt e r cept 844 V a r =0 .07 0 8; 2 22 le v els) . 845 Dis pers io n mod e l : ~ as .f ac t o r (o bs_ y e a r ) . 846 T able S 7b: Sim p l e s lo p e s o f a ge b y o ut come. 847 O utc ome A ge sl op e SE z p so n 0.523 0.0385 1 3 . 60 4 < 0. 0 001 d a ughte r 0.640 0.0371 17. 2 70 < 0. 0 001 T rend c o nt r a s t (so n − d aug ht er ) : e sti m a t e = − 0 . 117 , SE = 0. 0 480 , z = −2 .43 1 , p = 0 . 015 1 848 Ta b l e S 7 c : Simpl e s lop es of m at er n a l Elo b y outc om e . 849 Ou tco me Elo s lope S E z p so n 0.0925 0.04 89 1 . 8 93 0. 05 84 d a ughte r 0.1402 0.05 33 2.6 3 0 0. 00 85 T rend c o nt r a s t (so n − d aug ht er ) : e sti m a t e = − 0 . 047 8, SE = 0.0576 , z = − 0 .8 2 9, p = 0 .4069 850 Ta b l e S 7 d : S i mpl e slo pes of mat er n al ag e b y o utco m e . 851 .CC-BY-NC 4.0 International licenseavailable under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprintthis version posted February 17, 2026. ; https://doi.org/10.64898/2026.02.16.705899doi: bioRxiv preprint O utc ome Ma te rn a l a ge s lo pe SE z p so n − 0.0619 0.0469 −1.31 9 0. 18 70 d a ughte r − 0.0235 0.0406 −0. 57 9 0. 56 27 T rend c o nt r a s t (so n − d aug ht er ) : e sti m a t e = − 0 . 038 4, SE = 0.0570 , z = − 0 .6 7 3, p = 0 .5008 852 T able S 7e: Gr o up p air w is e co ntr asts ( emm e ans ; Co n tr as ts ar e o n t he log - odd s r a t i o sc ale; T u k e y - a d jus t ed 853 p- v a lu es) . 854 Co nt r a s t Est i m a te S E z p AK − B D 0.598 0 . 1 12 5. 34 0 <0.0 00 1 AK − K B −0 . 5 4 7 0 . 1 41 − 3 .8 7 2 0 . 0 00 6 AK − N H 0.189 0 . 1 16 1. 62 3 0. 36 54 BD − K B − 1.145 0.1 3 1 −8.70 5 <0.0 00 1 BD − N H − 0.409 0.1 0 4 −3.91 8 0. 00 05 KB − N H 0.735 0.1 3 4 5 . 4 73 < 0 . 00 0 1 Ta b l e S 8 : Conflic t m ode l ( betabin omia l GLM M; r es ponse = c bind(s ucces se s , tria ls−s ucces ses) ; 855 trials ≠ 0). 856 T able S 8a: F i x ed pr ed ict o r ou tc o m es . 857 Pr e di c t o r Es tima te S E z p S i g In te r c e pt - 3 . 538 0.09 8 -36 . 070 <0.001 * ** Outc ome: d au ghte r 0.21 3 0.07 2 2.9 4 0 0 .00 3 ** A ge (c e nt ered ; ye a r s) 0.69 4 0.04 9 1 4 . 21 0 <0.001 * ** Mate rn al El o (s ca l e d) 0.01 5 0.05 4 0.2 9 0 0 .77 3 Mate rn al a g e (s c al ed) - 0 . 016 0.05 4 -0. 3 00 0 . 7 65 Gr o u p: B D - 0 .840 0.11 9 -7.0 70 <0.001 ** * Gr o u p: K B 0.50 2 0.15 5 3 . 2 50 0 . 0 01 ** Gr o u p: N H -0 .2 4 7 0 . 1 20 - 2 .0 6 0 0 . 0 40 * Ou tco me ( dau g ht e r ) × age 0.06 4 0.06 4 0 . 9 90 0 . 3 22 Ou tco me ( dau g ht e r ) × E l o 0.04 2 0.07 0 0.6 0 0 0 .55 1 .CC-BY-NC 4.0 International licenseavailable under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprintthis version posted February 17, 2026. ; https://doi.org/10.64898/2026.02.16.705899doi: bioRxiv preprint Ou tco me ( dau g ht e r ) × mat er na l ag e 0.02 4 0.06 6 0 . 3 70 0. 7 1 4 Mo de l d et a i l s: N =52 4; AI C = 38 28 .7; BI C = 3 9 35. 2; lo gL i k = −1 889.3 . 858 R a ndom e ff ects : Mot her (I n t er c e pt V a r =0. 04 79; age V ar = 1. 0 0 e−0 8; 81 le v el s ) , C o d e ( In t er cept 859 V a r =0 .08 3 0; 2 22 le v els) . 860 Dis pers io n mod e l : ~ as .f ac t o r (o bs_ y e a r ) . 861 T able S 8b: Sim p l e s lo p e s o f a ge b y o ut come. 862 O utc ome A ge sl op e SE z p so n 0.69 4 0.0489 1 4 . 21 2 < 0. 0 001 d a ughte r 0.758 0.0503 15. 0 68 < 0. 0 001 T rend c o nt r a s t (so n − d aug ht er ) : e sti m a t e = − 0 . 063 7, SE = 0.0644 , z = − 0 .9 9 0, p = 0 .3224 863 Ta b l e S 8 c : Simpl e s lop es of m at er n a l Elo b y outc om e . 864 Ou tco me Elo s lope S E z p so n 0.0155 0.05 38 0 . 2 88 0. 77 35 d a ughte r 0.0573 0.05 94 0.9 6 4 0 . 3 35 2 T rend c o nt r a s t (so n − d aug ht er ) : e sti m a t e = − 0 . 041 8, SE = 0.0700 , z = − 0 .5 9 7, p = 0 .5505 865 Ta b l e S 8 d : S i mpl e slo pes of mat er n al ag e b y o utco m e . 866 O utc ome Ma te rn a l a ge s lo pe SE z p so n − 0.0160 0.0536 −0.29 9 0. 76 53 d a ughte r 0.00828 0.0480 0 .17 3 0. 86 29 T rend c o nt r a s t (so n − d aug ht er ) : e sti m a t e = − 0 . 024 3, SE = 0.0662 , z = − 0 .3 6 7, p = 0 .7139 867 T able S 8e: G rou p e st imate d mar gin a l means a n d c on t r a s ts (emmean s ; Con t r a st s a r e on the l o g- o d ds r a ti o 868 sc al e ; T uk e y- adj ust e d p - v alues) . 869 Co nt r a s t Est i m a te S E z p AK − B D 0.840 0 . 1 19 7. 06 5 <0.0 00 1 AK − K B −0 . 5 0 2 0 . 1 55 − 3 .2 4 9 0 . 0 06 4 AK − N H 0.247 0 . 1 20 2. 05 7 0. 16 75 BD − K B − 1.342 0.1 4 3 −9.38 7 <0.0 00 1 BD − N H − 0.593 0 . 1 11 −5.35 9 <0.0 00 1 .CC-BY-NC 4.0 International licenseavailable under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprintthis version posted February 17, 2026. ; https://doi.org/10.64898/2026.02.16.705899doi: bioRxiv preprint KB − N H 0.749 0.1 4 3 5. 24 7 <0.0 00 1 Ta b l e S 9 : Neare st-adul t distanc e model (Gamma GLM M; respo n s e = mean c loses t adult distance ; 870 log lin k ). 871 T able S 9a: F i x ed pr ed ict o r ou tc o m es . 872 Pr e di c t o r Es tima te S E z p S i g In te r c e pt 0.98 4 0.09 9 9 . 9 27 <0.0 0 1 * ** Outc ome: d au ghte r -0 .0 4 4 0 . 0 69 - 0 .6 4 0 0 . 5 22 Mate rn al a g e (s c al ed) 0.28 4 0.05 2 5 . 4 79 <0.0 0 1 * ** Mate rn al El o (s ca l e d) - 0 . 070 0.05 2 -1. 3 48 0. 17 8 Gr o u p: B D - 0 . 145 0.11 2 -1. 2 92 0. 19 6 Gr o u p: K B 0.30 0 0.17 2 1.7 4 2 0. 08 1 · Gr o u p: N H 0.06 6 0.11 7 0 . 5 67 0. 57 1 Ou tco me ( dau g ht e r ) × mat er na l ag e - 0 . 178 0.06 9 -2. 5 73 0. 01 0 * Ou tco me ( dau g ht e r ) × E l o 0.00 3 0.07 1 0 . 0 45 0. 96 5 Mo de l d et a i l s: N =23 3; AI C = 80 3 .4; BI C= 87 9 .3; logL i k= −37 9.7. 873 R a ndom i n t e r ce p t : Mot he r ( V a r =0. 0 528 ; 92 le v els) . 874 Dis pers io n mod e l : ~ as .f ac t o r ( y e a r ) . 875 T able S 9b: S i mple sl opes of m ater n al El o b y o utco m e. 876 Ou tco me Elo s lope S E z p so n − 0.0700 0.05 19 − 1 . 348 0.1776 d a ughte r − 0.0669 0.05 54 − 1 . 208 0.2272 T rend c o nt r a s t (so n − d aug ht er ) : e sti m a t e = − 0 . 003 16, SE = 0.070 8 , z = − 0 . 0 45, p = 0.9645 877 Ta b l e S 9 c : Simpl e s lop es of m at er n a l age b y o utco m e. 878 O utc ome Ma te rn a l a ge s lo pe SE z p so n 0.28 4 0.0519 5 . 4 79 < 0. 0 001 d a ughte r 0.106 0.0544 1 .95 7 0.05 0 3 T rend c o nt r a s t (so n − d aug ht er ) : e sti m a t e = 0.1 78 , SE = 0 .0691, z = 2 .57 3 , p = 0 .010 1 879 Ta b l e S 9 d : Gr oup pa ir wis e co ntr ast s ( e mm e ans ; Co n tr as ts a r e o n t he lo g sc a l e; T u k e y- adj u s t e d p - v a lu es) . 880 .CC-BY-NC 4.0 International licenseavailable under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprintthis version posted February 17, 2026. ; https://doi.org/10.64898/2026.02.16.705899doi: bioRxiv preprint Co nt r a s t Est i m a te S E z p AK − B D 0.1448 0.112 1. 29 2 0. 56 78 AK − K B − 0.3000 0.172 −1. 742 0. 30 17 AK − N H − 0.0663 0.117 −0.567 0. 94 18 BD − K B − 0.4448 0.16 4 −2. 712 0. 03 38 BD − N H − 0.2110 0.101 −2.100 0. 15 32 KB − N H 0.2337 0.166 1. 40 8 0. 49 42 881 .CC-BY-NC 4.0 International licenseavailable under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprintthis version posted February 17, 2026. ; https://doi.org/10.64898/2026.02.16.705899doi: bioRxiv preprint 882 F ig u re S 1 : P r e d i cto rs of o ff sp ri n g s ex ra t io at b i r th. M od e l -pr e dict e d p r oba bil it y that a birt h w as a da u g ht er 883 ( 1 = d a ug hte r , 0 = son ) p l ot te d ag ain s t ma te rna l an d so ci a l p r e di c t o rs . Poin t s show o b s e r ve d b i rth 884 ou tcom e s (0 / 1, j itt e r e d ; r a w d at a p oi nt s); solid li nes s ho w mod el pr e dicti o ns a n d s h aded r i b b o ns i nd ica t e 885 9 5 % C I s . ( a ) M a t e r n a l a g e a t b i r t h ( s c a l e d ) : p r o b a b i l i t y o f p r o d u c i n g a d a u g h t e r i n c r e a s e d w i t h m a t e r n a l 886 age . ( b) Nu m ber of f em al e s p r e s ent i n t he gr oup dur i ng t he m a ti n g s e a s on (s cal ed ) : n o e v id enc e th at l o c a l 887 f e m al e abu nd anc e pr ed ict ed off spri n g s e x . (c ) Ma t e r nal d o m i n a nce r a nk ( sc a l ed Elo s cor e): n o e vid enc e 888 t hat mate rna l r ank p r e d i cte d o f fs p rin g s ex a t bi r th. 889 .CC-BY-NC 4.0 International licenseavailable under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprintthis version posted February 17, 2026. ; https://doi.org/10.64898/2026.02.16.705899doi: bioRxiv preprint 890 Fi gur e S 2 : Pr edic t or s of r epr o d u cti v e p a c e . Mod el -pr ed ic t e d p r ob ab ilit y th at a m othe r g a v e b ir t h i n the 891 br e e d i n g s e a s on f ollo wi ng her pr e v io u s b i r th (1 /0 ) , s h ow n a c r oss m at er n al ch ar act e rist ics a nd o f fs pri n g 892 se x. P o i nt s s ho w obs er v ed r e pr oduct i v e o u tc omes ( 0 /1, ji tt er ed ; r a w data po i nts ) ; l i n e s a nd s had ed 893 r i b b o n s s ho w m o d e l p r e d i c t i o n s ± 9 5 % C I , a n d p o i n t s w i t h e r r o r b a r s i n ( b ) i n d i c a t e p r e d i c t e d m e a n s ± 894 9 5 % C I. ( a ) Mate r na l age ( s c a le d ) : n o e v id en ce th at ma t ern a l a g e p r e d i ct ed g i v ing bi r t h t he fo l lo w ing 895 se as o n. ( b) O ffs pr i n g s e x ( s on /d a u g ht e r ): mo th e r s w e r e m ar gi nall y mor e l i k el y t o r epr oduce a gai n a f ter 896 g i v i n g b i r t h t o d a u g ht e r s t h a n t o s o n s . ( c ) M a t e r n a l d o m i n a n c e r a n k ( s c a l e d E l o s c o r e ) : n o e v i d e n c e t h a t 897 m a t er n al r a nk pr ed ict ed gi vi ng b ir th t h e f o l lo wi ng s ea so n . 898 .CC-BY-NC 4.0 International licenseavailable under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprintthis version posted February 17, 2026. ; https://doi.org/10.64898/2026.02.16.705899doi: bioRxiv preprint 899 Fi gur e S3: Ma t er na l co aliti ona ry su p por t t o w a r d o f fspri n g a c r o s s mat er nal r ank , m at er nal ag e, a n d offs pri n g 900 age . M od e l -pr e dict e d pr o bab ilit y t hat a m o ther supp ort ed h er of fspr i ng i n a co nflict ( 1 /0) pl ot ted a g a i nst 901 m a t er n al r a n k , m a t er n a l age, a n d off spri n g age , sho wn s epar a t e l y f or s o n s (blu e) a nd dau gh t e r s ( r ed) . 902 P o i n t s r e p r es e n t i n d i vi d u a l c o nf li c t ob s er v a t i o n s ( j i t t e r e d ; r a w d a t a p o i n t s ) ; l i n e s s ho w m o d e l p r e d i c t i o n s 903 w ith s h aded 95 % co nf id enc e in ter v al s. ( a ) Mat er n al do mi n anc e r an k ( sc a le d Elo s cor e ) : pr oba bil it y of 904 ma te rna l s u pp o rt in crea s e d w it h ma te rna l r a nk. (b ) Ma te rna l a g e ( s c a l ed ) : p rob a bi li ty o f ma te rna l 905 support d ecr e as ed w it h mat er n al a g e . ( c ) Offs pr i ng age (s cal e d): pr o b abilit y o f m a t er na l s u pp ort 906 decr e as ed w ith off s p r i n g a ge. 907 .CC-BY-NC 4.0 International licenseavailable under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprintthis version posted February 17, 2026. ; https://doi.org/10.64898/2026.02.16.705899doi: bioRxiv preprint