February 4 2016

5:00 pm 154 BSRB

EcoEvoPub Series

Graduate Student Presentations


Richard Hedley
Department of Ecology and Evolutionary Biology, UCLA

Incorporating knowledge of syntax yields new perspectives on song matching in birds

Many songbird species regularly engage in song matching, where one individual repeats the song type of its rival during counter-singing. This behavior has been hypothesized to convey aggressive intentions during territorial defense, and has been proposed as a driver of the evolution of song repertoires and geographic dialects in birds. Analyses of song matching experiments have typically relied upon assumptions that are seriously violated in the songs of Cassin’s Vireo. I will discuss these issues and present a solution that, when applied to data from a set of playback experiments on this species, yielded an unexpected insight into the proximate mechanisms of vocal interactions in this species, with potential implications for the interpretation of song matching in general.

Jacqueline Robinson
Department of Ecology and Evolutionary Biology, UCLA

Genomic flatlining in the endangered island fox (Urocyon littoralis)

With species declining worldwide due to exploitation and habitat loss, a vital element in mitigating future biodiversity loss will include understanding the genetic consequences of small population size and isolation. Population genetics theory holds that small populations in isolation will suffer from declining diversity, increasing genetic load, and eventual extirpation, in a process dubbed the “extinction vortex.” Island species therefore present an ideal system for empirically studying the impacts of small population size and isolation. Island foxes (Urocyon littoralis) are dwarfed descendants of the mainland gray fox (U. cinereoargenteus) inhabiting California’s Channel Islands. We sequenced complete genomes from each island population and the mainland to examine heterozygosity and deleterious variation within individual genomes. The genome of the San Nicolas Island fox is almost entirely monomorphic, and retains the lowest observed genomic heterozygosity of any outbred species to date. Furthermore, genomes from all island populations exhibit reduced variation and an elevation in the proportion of deleterious alleles, resulting from strong genetic drift and reduced efficacy of selection. Through demographic simulations, we show that the observed patterns of heterozygosity within the island genomes can be attributed to severe bottlenecks and long-term small population size.











































































































































































































































































































































































































































































































































































































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