When one phenotype is not enough: divergent evolutionary trajectories govern venom variation in a widespread rattlesnake species

Artículo 10 páginas, 3 figuras 1 tablaUnderstanding the origin and maintenance of phenotypic variation, particularly across a continuous spatial distribution, represents a key challenge in evolutionary biology. For this, animal venoms represent ideal study systems: they are complex, variable, yet easily quantifiable molecular phenotypes with a clear function. Rattlesnakes display tremendous variation in their venom composition, mostly through strongly dichotomous venom strategies, which may even coexist within a single species. Here, through dense, widespread population-level sampling of the Mojave rattlesnake, Crotalus scutulatus, we show that genomic structural variation at multiple loci underlies extreme geographical variation in venom composition, which is maintained despite extensive gene flow. Unexpectedly, neither diet composition nor neutral population structure explain venom variation. Instead, venom divergence is strongly correlated with environmental conditions. Individual toxin genes correlate with distinct environmental factors, suggesting that different selective pressures can act on individual loci independently of their co-expression patterns or genomic proximity. Our results challenge common assumptions about diet composition as the key selective driver of snake venom evolution and emphasize how the interplay between genomic architecture and local-scale spatial heterogeneity in selective pressures may facilitate the retention of adaptive functional polymorphisms across a continuous space.Funding: Leverhulme Trust Grant RPG 2013-315 to WW, Santander Early Career Research Scholarship to GZ, Ministerio de Economía y Competitividad Grant BFU2013-42833-P to JJC.Peer reviewe

Genotype and diet datasets

The excel file include one spreadsheet with Crotalus scutulatus samples used for population genetic analysis with geographic coordinates, population assignment and microsatellite genotype information. A second spreadsheet includes a count table of prey items identified in the stomach content of preserved specimen

Genotype and diet datasets

The excel file includes three spreadsheets: the first one includes with all the museum specimen of *Crotalus scutulatus* inspected for stomach content; the second one includes a count table of prey items identified in the preserved specimen; The third spreadsheet includes the samples used for population genetic analysis with geographic coordinates, population assignment and microsatellite genotype information

Data from: When one phenotype is not enough - divergent evolutionary trajectories govern venom variation in a widespread rattlesnake species

Understanding the origin and maintenance of phenotypic variation, particularly across a continuous spatial distribution, represents a key challenge in evolutionary biology. For this, animal venoms represent ideal study systems: they are complex, variable, yet easily quantifiable molecular phenotypes with a clear function. Rattlesnakes display tremendous variation in their venom composition, mostly through strongly dichotomous venom strategies, which may even coexist within single species. Here, through dense, widespread population-level sampling of the Mojave rattlesnake, Crotalus scutulatus, we show that genomic structural variation at multiple loci underlies extreme geographic variation in venom composition, which is maintained despite extensive gene flow. Unexpectedly, neither diet composition nor neutral population structure explain venom variation. Instead, venom divergence is strongly correlated with environmental conditions. Individual toxin genes correlate with distinct environmental factors, suggesting that different selective pressures can act on individual loci independently of their co-expression patterns or genomic proximity. Our results challenge common assumptions about diet composition as the key selective driver of snake venom evolution and emphasise how the interplay between genomic architecture and local-scale spatial heterogeneity in selective pressures may facilitate the retention of adaptive functional polymorphisms across a continuous space