Presented By: Ecology and Evolutionary Biology
EEB Thursday Seminar: Molecular evolutionary genetics of the “two rules of speciation” in Drosophila
Daven Presgraves, University of Rochester
Speciation involves the gradual evolution of reproductive incompatibilities— including prezygotic incompatibilities that prevent the formation of species hybrids and intrinsic postzygotic genetic incompatibilities that render hybrids sterile or inviable. Two strong “rules of speciation” implicate a special role for sex chromosomes in the evolution of postzygotic genetic incompatibilities: Haldane’s rule, the observation that hybrids of the heterogametic (XY or ZW) sex preferentially suffer hybrid sterility and inviability; and the large X-effect, the observation that the X chromosome has a disproportionately large effect on hybrid sterility. Despite decades of effort, why the X chromosome plays a special role in speciation remains unclear. I will present results from our integrated genetic and genomic studies of speciation among the three closely related species of the Drosophila simulans species complex— D. simulans, D. sechellia, and D. mauritiana. Our high-resolution genetic mapping studies, speciation genomics analyses, and molecular identification of a new hybrid sterility gene enable new inferences about the molecular and evolutionary basis of the large X-effect and its consequences for speciation.
Light refreshments served at 4 p.m.
Light refreshments served at 4 p.m.
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