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Departmental Seminars

Fall Semester 2014

Unless noted otherwise, all seminars are held at 12 noon in SSMB Room 138.

Monday, February 2, 2015

Hybridization, Hybrid Species, and the Organization of Genomic Diversity in a Butterfly Species Complex

Chris Nice, Texas State University [website]

Secondary contact between formerly isolated species or populations can create opportunities for gene exchange. Suture zones (areas of secondary contact) therefore represent natural laboratories for studying the consequences of hybridization and the consequent effects on the distribution of genetic variation and phenotypic novelty. We investigated the organization of diversity in the butterfly genus Lycaeides in western North America using ecological, morphological and genetic/genomic data. Population genomic data from next-generation sequencing were employed to test the hypothesis that high-altitude (alpine) populations of Lycaeides in the Sierra Nevada and other, western mountain ranges constitute independent

hybrid species. Consistent with this hypothesis, we found that these alpine populations possess mosaic genomes with alleles from L. anna, L. idas and L. melissa. These hybrid populations are also differentiated from, and potentially much younger than, their parental species. Admixture (via hybridization) appears to be almost entirely historical, with only geographically limited evidence of contemporary gene exchange. The alpine populations also exhibit unique ecological adaptations to their habitat that may contribute to reproductive isolation. These results suggest that patterns of genetic variation in this group are multifaceted, and we argue that this complexity challenges simplistic notions concerning the organization of biological diversity into discrete, easily delineated and hierarchically structured entities.

Monday, February 9, 2015

The Evolution of Goodness

Lee Dugatkin, University of Louisville [website]

In a world supposedly governed by ruthless survival of the fittest, why do we see acts of goodness in both animals and humans? This problem plagued Charles Darwin in the 1850s as he developed his theory of evolution through natural selection. Indeed, Darwin worried that the goodness he observed in nature could be the Achilles heel of his theory. Ever since then, scientists and other thinkers have engaged in a fierce debate about the origins of goodness that has dragged politics, philosophy, and religion into what remains a major question for evolutionary biology.