34 Oral - Platform Session #3 Speciation, Hybridization, and Introgression
Thursday June 09, 11:05 AM - 11:20 AM

Authors:
Gregg Thomas ^1,2; Carl Hutter ³; Ana Paula Assis ¹; Emily Kopania ¹; Sebastian Mortimer ¹; Colin Callahan ¹; Kevin Rowe ⁴; Jacob Esselstyn ³; Jeffrey Good ¹

Affiliations:
1) University of Montana, Missoula, MT, USA; 2) Harvard University, Cambridge, MA, USA; 3) Louisiana State University, Baton Rouge, LA, USA; 4) Museum Victoria, Melbourne, VIC, AU

Keywords:
Comparative genomics & genome evolution

Adaptation and speciation ultimately depend on evolution at the molecular level, yet relatively little is known about the dynamics of molecular evolution during rapid species radiations. The Old World rats and mice (Murinae) represent one of the most species-rich radiations in mammals with extensive phenotypic and ecological variation. This diverse group is comprised of more than 630 species accounting for over 10% of all mammalian species, arising in only ~15 million years. Laboratory mice and rats are embedded within this massive radiation, providing a compelling opportunity to leverage these powerful model systems to understand the evolution of the extensive phenotypic and ecological variation found across this group. Here, we integrate comparative genomics with quantitative ecomorphology, biogeography, and life history data to understand the diversification of lineages, phenotypes, and genes across this speciose radiation. Using whole exomes from 209 species, we resolve their evolutionary history in the face of substantial phylogenetic discordance. We developed methods to accurately estimate substitution rates in the species tree while accounting for gene tree discordance and to heuristically prune large phylogenies to maximize concordance between the species tree and underlying gene trees. Using these methods, we identified lineages and genes that have undergone episodic positive selection during the evolution of rats and mice. We examined correlations between molecular evolution and the repeated colonization events in the Indo-Australian archipelago to test if signatures of convergent or adaptive molecular evolution coincide with bursts in phenotypic evolution. Finally, we map rates of cranial shape and body size evolution onto the history of the rodent radiation. This study is the largest comparative molecular evolution study of rodents to date and provides an opportunity to understand molecular evolution during rapid radiations in the context of two of the most important model organisms for basic and biomedical genetic research.