de Solan, T. | bioRxiv Science

bioRxiv2023

Color polymorphism and conspicuousness do not increase speciation rates in Lacertids

Conspicuous body colours and colour polymorphism have been hypothesized to increase rates of speciation. Conspicuous colours are evolutionary labile, and often involved in intraspecific sexual signalling and thus may provide a raw material from which reproductive isolation can easily evolve, while polymorphism could favour rapid evolution of new lineages through morphic speciation. Here, we investigated the influence of the presence/absence of conspicuous colourations, and of colour polymorphism on the speciation of Lacertids. We used several state-dependent diversification models, and showed that, regardless of the methods, conspicuous colourations and colour polymorphism were not related to species speciation. While the lack of correlation between conspicuous colourations and speciation rates is in line with most of the literature testing this hypothesis, the results for colour polymorphism contradict previous studies, and question the generality of the morphic speciation hypothesis.

evolutionary biology↗

bioRxiv2019

Looking for mimicry in a snake assemblage using deep learning

Batesian mimicry, with its highly colorful species and astonishing mimic-model resemblance, is a canonical example of evolution by natural selection. However, Batesian mimicry could also occur in inconspicuous species and rely on subtle resemblance. Although potentially widespread, such instances have been rarely investigated, such that the real frequency of Batesian mimicry has remained largely unknown. To fill this gap, we developed a new approach using deep learning to quantify the resemblance between putative mimics and models from photographs. We applied this method to quantify the frequency of Batesian mimicry in Western Palearctic snakes. Potential mimics were revealed by an excess of resemblance with sympatric venomous snakes compared to random expectations. We found that 8% of the non-venomous species were potential mimics, among which all were imperfect mimics. This study is the first to quantify the frequency of Batesian mimicry in a whole community of vertebrates, and shows that even concealed species can be reliably identified as potential models. Our approach should prove useful to detect mimicry in other communities, and more generally it highlights the benefits of deep learning for quantitative studies of phenotypic resemblance.

evolutionary biology↗