Larval Pigmentation Reveals Environmental and Genetic Influences in Hybridizing Ambystoma Salamanders

Larval Pigmentation Reveals Environmental and Genetic Influences in Hybridizing Ambystoma Salamanders | Authorea try { document.documentElement.classList.add('js'); } catch (e) { } var _gaq = _gaq || []; _gaq.push(['_setAccount', 'G-8VDV14Y67G']); _gaq.push(['_trackPageview']); (function() { var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s); })(); Skip to main content Preprints Collections Wiley Open Research IET Open Research Ecological Society of Japan All Collections About About Authorea FAQs Contact Us Quick Search anywhere Search for preprint articles, keywords, etc. Search Search ADVANCED SEARCH SCROLL Ecology and Evolution This is a preprint and has not been peer reviewed. Data may be preliminary. 3 July 2025 V1 Latest version Share on Larval Pigmentation Reveals Environmental and Genetic Influences in Hybridizing Ambystoma Salamanders Authors : Alfredo Ascanio 0000-0001-9987-7977 [email protected] , Victor Fitzgerald , Patrick Altomari , Jason Bracken 0000-0003-4826-3427 , and Tereza Ježková Authors Info & Affiliations https://doi.org/10.22541/au.175156760.03821425/v1 Published Ecology and Evolution Version of record Peer review timeline 352 views 229 downloads Contents Abstract Supplementary Material Information & Authors Metrics & Citations View Options References Figures Tables Media Share Abstract Closely related species may produce hybrids, and these hybrids often display intermediate traits that can influence fitness and reproductive isolation. In this study, we examine Ambystoma barbouri and Ambystoma texanum, two sister salamander species that breed in contrasting aquatic habitats with differing levels of ultraviolet radiation (UVR) exposure. Although these species can hybridize, it remains unclear whether hybrid pigmentation responses to UVR confer an advantage, a disadvantage, or are simply intermediate between parental forms. Pigmentation in salamanders is regulated by chromatophores, melanophores and xanthophores, which help mitigate UVR-induced damage. Given previous knowledge on the species, habitats, and behaviors, we hypothesized that: (1) A. barbouri would show stronger UVR-induced pigmentation (i.e., greater darkening) than A. texanum, due to its exposure to clearer, shallower streams; (2) hybrids would exhibit intermediate responses; and (3) xanthophore coverage would remain stable or decrease under UVR as melanophores expand. To test these hypotheses, we conducted a fully factorial breeding experiment using pure and reciprocal hybrid crosses, exposing larvae to four UVR durations (0, 1, 4, and 12 hours). We quantified skin darkness and chromatophore-specific pigmentation using standardized digital image analysis, Bayesian beta regression, and Bayesian compositional regression. Our results supported all three hypotheses. A. barbouri showed greater darkening under UVR exposure than A. texanum, and hybrids exhibited intermediate responses, but with a greater similarity toward their maternal phenotype. Xanthophore coverage remained stable or declined with increasing UVR exposure, evidencing that their main purpose is different from UVR protection. These findings raise the possibility that hybrids could experience reduced performance if intermediate pigmentation is suboptimal, but that maternal effects may offset some of these disadvantages. Supplementary Material File (ecoevo_uv_main.docx) Download 129.79 KB File (ecoevo_uv_titlepage.docx) Download 33.61 KB Information & Authors Information Version history V1 Version 1 03 July 2025 Peer review timeline Published Ecology and Evolution Version of Record 3 Aug 2025 Published Copyright This work is licensed under a Non Exclusive No Reuse License. Collection Ecology and Evolution Keywords comparative ecological experiment evolutionary ecology freshwater natural history terrestrial vertebrate Authors Affiliations Alfredo Ascanio 0000-0001-9987-7977 [email protected] Miami University View all articles by this author Victor Fitzgerald Miami University View all articles by this author Patrick Altomari Miami University View all articles by this author Jason Bracken 0000-0003-4826-3427 Miami University View all articles by this author Tereza Ježková Miami University View all articles by this author Metrics & Citations Metrics Article Usage 352 views 229 downloads .FvxKWukQNSOunydq8rnd { width: 100px; } Citations Download citation Alfredo Ascanio, Victor Fitzgerald, Patrick Altomari, et al. Larval Pigmentation Reveals Environmental and Genetic Influences in Hybridizing Ambystoma Salamanders. Authorea . 03 July 2025. DOI: https://doi.org/10.22541/au.175156760.03821425/v1 If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download. For more information or tips please see 'Downloading to a citation manager' in the Help menu . Format Please select one from the list RIS (ProCite, Reference Manager) EndNote BibTex Medlars RefWorks Direct import Tips for downloading citations document.getElementById('citMgrHelpLink').addEventListener('click', function() { popupHelp(this.href); return false; }); $(".js__slcInclude").on("change", function(e){ if ($(this).val() == 'refworks') $('#direct').prop("checked", false); $('#direct').prop("disabled", ($(this).val() == 'refworks')); }); View Options View options PDF View PDF Figures Tables Media Share Share Share article link Copy Link Copied! Copying failed. 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