Plasticity matches phenotype to local conditions despite genetic homogeneity across 13 snake populations

Type Article
Date 2021-01
Language English
Author(s) Bonnet XavierORCID1, Brischoux François1, Briand Marine2, Shine Richard3
Affiliation(s) 1 : CEBC, UMR 7372 CNRS and University of La Rochelle, 79360 Villiers en Bois, France
2 : ODE, Ifremer, Issy-les-Moulineaux, France
3 : Department of Biological Sciences, Macquarie University, New South Wales 2109, Australia
Source Proceedings Of The Royal Society B-biological Sciences (0962-8452) (The Royal Society), 2021-01 , Vol. 288 , N. 1943 , P. 20202916 (8p.)
DOI 10.1098/rspb.2020.2916
Keyword(s) gape limited, jaw size, Laticauda, local adaptation, New Caledonia, sea krait
Abstract

In a widespread species, a matching of phenotypic traits to local environmental optima is generally attributed to site-specific adaptation. However, the same matching can occur via adaptive plasticity, without requiring genetic differences among populations. Adult sea kraits (Laticauda saintgironsi) are highly philopatric to small islands, but the entire population within the Neo-Caledonian Lagoon is genetically homogeneous because females migrate to the mainland to lay their eggs at communal sites; recruits disperse before settling, mixing up alleles. Consequently, any matching between local environments (e.g. prey sizes) and snake phenotypes (e.g. body sizes and relative jaw sizes (RJSs)) must be achieved via phenotypic plasticity rather than spatial heterogeneity in gene frequencies. We sampled 13 snake colonies spread along an approximately 200 km northwest–southeast gradient (n > 4500 individuals) to measure two morphological features that affect maximum ingestible prey size in gape-limited predators: body size and RJS. As proxies of habitat quality (HQ), we used protection status, fishing pressure and lagoon characteristics (lagoon width and distance of islands to the barrier reef). In both sexes, spatial variation in body sizes and RJSs was linked to HQ; albeit in different ways, consistent with sex-based divergences in foraging ecology. Strong spatial divergence in morphology among snake colonies, despite genetic homogeneity, supports the idea that phenotypic plasticity can facilitate speciation by creating multiple phenotypically distinct subpopulations shaped by their environment.

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How to cite 

Bonnet Xavier, Brischoux François, Briand Marine, Shine Richard (2021). Plasticity matches phenotype to local conditions despite genetic homogeneity across 13 snake populations. Proceedings Of The Royal Society B-biological Sciences, 288(1943), 20202916 (8p.). Publisher's official version : https://doi.org/10.1098/rspb.2020.2916 , Open Access version : https://archimer.ifremer.fr/doc/00677/78892/