The social environment has little impact on inbreeding depression in a social mammal

This is a Preprint and has not been peer reviewed. This is version 1 of this Preprint. You must log in to post a comment. There are no comments or no comments have been made public for this article. This is a Preprint and has not been peer reviewed. This is version 1 of this Preprint. Add a Comment You must log in to post a comment. Comments There are no comments or no comments have been made public for this article. Inbreeding depression describes the decline in fitness caused by breeding between relatives and is now known to be widespread in natural populations. Yet, its relative strength across different fitness components and its sensitivity to social and demographic environments are poorly understood. Using nearly 30 years of life-history, behavioural, pedigree and genomic data from a wild population of spotted hyenas (Crocuta crocuta) in the Ngorongoro Crater, Tanzania, we tested for inbreeding depression in three key fitness components and evaluated whether it is moderated by socio-demographic factors. We estimated individual inbreeding using both pedigree-based and genomic-based approaches. We found evidence for inbreeding depression in two out of three fitness components: when inbreeding coefficients increased, both lifespan and lifetime reproductive success decreased. Juvenile survival also decreased, but not significantly so. We found little evidence that the strength of inbreeding depression varied systematically with sex, social rank, or clan size. Genomic and pedigree estimates of inbreeding yielded broadly comparable conclusions about inbreeding depression when the pedigree was restricted to individuals with at least three known grandparents. Together, these results demonstrate inbreeding depression may be present, and yet not strongly influenced by the social environment, in a socially structured wild population. https://doi.org/10.32942/X2NT0S Life Sciences FGRM, FPED, inbreeding depression, LRS, relatedness, social mammals, spotted hyena. Published: 2026-05-08 23:15 Last Updated: 2026-05-08 23:15 CC BY Attribution 4.0 International Data and Code Availability Statement: The raw sequencing data are deposited in the Genbank with the NCBI BioProject accession no. PRJNA951614. Code used for bioinformatic analyses of genetic data can be found at: and https://git.imp.fu-berlin.de/begendiv/radseq-preprocessing-pipeline/-/blob/main/scripts/digestion/checkRestrictionSites.py). R code and data needed to reproduce analyses and results, including all tables and figures, can be found at https://github.com/hyenaproject/inbreeding_depression_2026. Language: English