How species form is a central question in evolutionary biology. A major challenge in contemporary speciation research is linking microevolutionary processes, such as natural and sexual selection, within populations to broader macroevolutionary patterns of divergence among species. Much of my research is focused on the evolution of color, pattern, behavior, chemical signals, and other traits under both natural and sexual selection that vary geographically within and among species to understand how species diverge into distinct lineages. I take an integrative approach that leverages phylogenetics, morphology, behavior, and both field and lab work to study species traits in space and through time. My Ph.D. dissertation is on the evolutionary causes and consequences of color polymorphism.
So what is color polymorphism and why do we care?
Color polymorphism is the presence of two or more discrete color morphs within a breeding population. Biologists have long been mesmerized by color polymorphism because it defies evolutionary expectations. Evolutionary processes like natural selection, sexual selection, and genetic drift reduce genetic and phenotypic variation within populations.
Further than the interesting evolutionary mystery color polymorphism poses to evolutionary biologists - color polymorphism is thought to be capacious starting variation for speciation, a process in biology we still don’t fully understand.
COLOR MORPH DIFFERENCES IN FUNCTIONAL & SIGNALING TRAITS
Color polymorphism defies evolutionary expectations by maintaining striking phenotypic variation within a single species. Stable polymorphism within a population is hypothesized to be related to correlational selection of other phenotypic traits among morphs. Here, we report on a previously unknown throat color polymorphism in the Aegean Wall Lizard (Podarcis erhardii) and examine morph-correlated differences in traits important to social behavior and communication: maximum bite force capacity and chemical signal profile.
We'll share our exciting results once our manuscript has gone through peer review - check back soon!
This project is in collaboration with Simon Baeckens, Colin Donihue, José Martín, Panayiotis Pafilis, and Danielle Edwards. Thanks to the amazing UC Merced undergraduate field assistants who helped catch and care for lizards: Indiana Madden, Adam Rosso, and Cynthia Ramos!
THE EVOLUTION OF COLOR POLYMORPHISM IN THE LACERTIDAE
Color polymorphism, or the presence of two or more discrete color phenotypes within a breeding population, is phylogenetically widespread across the tree of life but taxonomically quite rare… Color polymorphic species defy evolutionary expectations by maintaining highly variable heritable phenotypes over space and time. The evolution of striking intra-species variability within populations has particularly interesting implications for sympatric speciation, as the same processes that act to maintain morph diversity within color polymorphic species are likely the very mechanisms involved in its loss and lineage divergence.
We are reconstructing evolutionary relationships in a speciose family of lizards, the Lacertidae, and using phylogenetic comparative methods to understand the evolutionary history of color polymorphism and test if color polymorphic lineages are engines of speciation.
GEOGRAPHIC VARIATION IN COLOR POLYMORPHISM IN PODARCIS
Evolutionary theory predicts that color polymorphic species are ripe for speciation due to striking variation amongst multiple discrete phenotypes within and among population. But how does population-level variation in color polymorphism change across an entire species distribution? And what affect does this geographic variation have on the mode and tempo of divergence (both morphological and genetic)? TeamSavres 2017-2020 (Team Lizards in Greek) and I travelled to the very farthest reaches of the Aegean wall lizard's (Podarcis erhardii) distribution, exploring more than 40 Aegean islands, in search of lizards to describe and explain color morph diversity across the archipelago.
COLOR MORPH-CORRELATED BEHAVIOR IN PODARCIS ERHARDII
Color morphs within color polymorphic species can exhibit alternative mating behaviors that are similar to a rock-paper-scissors game, where one strategy beats one strategy beats and is beaten by another. We think these alternative strategies are involved in the evolutionary maintenance of color polymorphism. We captured over 100 adult male lizards to find out if different color morphs (orange, yellow, and white) exhibit different ritualized aggressive behaviors when put in an arena with one refuge resource.