Allison J. Shultz, PhD
Assistant Curator, Natural History Museum of Los Angeles County, Dept. of Ornithology
Research Website
Evolution across timescales: comparative and population genomics studies of host-pathogen co-evolution in birds
Friday, March 1, 2019
12 PM
RRI 101
Abstract: Infectious disease produces some of the strongest selective forces on natural populations across the tree of life. The signatures of pathogen-mediated evolution on host genomes have been described for several traditional model organisms, but few studies of more diverse organisms have detected such signatures beyond candidate immune loci. Here, I combine population and comparative genomics to study the dynamics of pathogen-mediated selection at across evolutionary timescales in birds. First, I use alignments of 39 bird genomes to estimate parameters related to positive selection for 11,000 genes conserved across birds. I use functional pathway analyses, transcriptome data, and comparisons with mammals to show that pathogens, particular viruses, consistently target the same genes across divergent clades, and that these genes are hotspots of host-pathogen conflict over deep evolutionary time. Second, I use whole genome resequencing data to estimate parameters of selection at the population level across birds, and investigate if the same genes observed under selection at deep evolutionary timescales are under selection at shallow evolutionary timescales. Finally, I use genomes of a songbird collected across time and space to understand the demographic impacts of two anthropogenic disturbances, an introduction event and a novel pathogen. I find that the demographic history had the largest genomic impact, and that pathogen-mediated selection likely occurred at many different regions of the genome.
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