February 9 2017

11:00 158 HH

Gil Rosenthal
Department of Biology
Texas A&M University

Mate-choice mechanisms and the evolutionary process


The origin of species remains the central problem of evolutionary biology. This is a complex problem to unravel, in part because speciation and hybridization depend critically on individual mating decisions. The mechanisms underlying these decisions are subject to functional constraints and responsive to environmental and social influences. Our work uses behavioral, environmental, and genomic approaches to understand the dynamics of reproductive isolation and hybridization between sister species of livebearing fish, Xiphophorus birchmanni and X. malinche. Extensive behavioral studies by our group have shown that conspecific mate preferences in these species depend on divergent, experience-dependent female responses to male pheromone signals. Conspecific mate preferences are so fragile that they fail when the physical or social environment is disrupted. This fragility of mate preferences may explain rampant recent hybridization between these species in their natural habitats following an increase in anthropogenic disturbance within the last few decades. Evolutionary-genomic analyses of contemporary patterns of mating and introgression, as well as phylogenomic analyses of historical patterns of genetic exchange, suggest that punctuated episodes of interspecific genetic exchange are a defining feature of Xiphophorus evolution. While early-generation birchmanni-malinche hybrids show reduced fitness, later-generation hybrids likely persist due to purging of genetic incompatibilities, adaptation to intermediate thermal environments, and increased attractiveness of hybrid males. Ongoing work centers on a long-term study of how environmental gradients and mating preferences interact to shape hybrid phenotypes and patterns of gene flow across lineages.















































































































































































































































































































































































































































































































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