Phylogeny, Andean Biogeography, and Multivariate Evolution in Phyllotine Rodents

Florida State University, Tallahassee FL

Investigators

Abstract

Abstract This project consists of two integrated parts: a detailed reconstruction of the evolutionary history of the populations that make up several closely related species of leaf-eared mice (Phyllotis), and a test of whether those species share the same inherent tendencies for the evolution of morphology. I will sequence at least 5 genes, some inherited from just the mothers, some from just the fathers, and some inherited from both, for over 200 mice collected from more than 100 localities throughout the Andes and nearby areas where Phyllotis lives. Those gene sequences will be used to estimate the evolutionary genealogy, or phylogeny, for those populations. This phylogeny will show the role that the Andes or other physical features have played in promoting speciation, estimate rates of gene flow across the species ranges, and test models of speciation. At the same time, we will establish controlled breeding colonies for 4 of the species. These breeding programs are needed to calculate the heritability of morphological traits and how much those traits are correlated with each other due to genetic control and developmental processes. These genetic parameters, summarized by the genetic variance-covariance matrix, G, will be compared among the species to determine if they remain constant over evolutionary time-scales. If the environmental effects on those G matrices is small or consistent, then the morphological data (32 measurements of the skull) will be combined with already collected measurements from more than 30 populations, and analyzed using the phylogeny discussed above, for a detailed exploration of the evolution of those inherent tendencies that are described by the G matrix. This study will address several critical questions in evolutionary biology. Most importantly, it has been suggested that microevolution (population and quantitative genetics) is decoupled from macroevolution (the long term changes we see among species). Perhaps the best method to unify these two fields is through quantitative genetics, but to do so requires that the G matrix evolves in a predictable manner. This will be the most comprehensive and phylogenetically based study to test that question. Additionally, this study will be the first to explore the biogeographic history of the southern Andes and southern South America in a comprehensive manner. Because geographic populations of Phyllotis are very distinct from each other genetically, their phylogenetic history can be estimated in great detail. That will allow robust tests of several models of how new species originate. By integrating a detailed phylogeny with the comparative quantitative genetics, we will also be able to test the interplay of geography, population history, and quantitative genetics to produce morphological evolution and diversification of species. Few if any studies have combined all these types of data to address these questions.