Population Genomics of Sea Stars

Michael Hart

Abstract

Project Abstract ? We study the evolution of sex in the ocean. We use sea stars as a model system for analyzing population genetic variation and how that variation is shaped over evolutionary time by differences among species in mate selection and gene flow. New methods in this work use high-throughput sequencing methods to discover new genes expressed on sea star sperm and egg surfaces, and to analyze the pattern of molecular evolution of those genes compared to other parts of the genome. We use IRMACS computational and bioinformatics resources in those analyses.Project Description ? My research group uses molecular genetic methods and data in evolutionary biology. The specific research area is the analysis of population genetic variation, and comparative studies of population genetics among species that differ in demographic variables such as mate choice, population size, and gene flow. We use closely related species of sea stars as the model organisms for this study. Our current studies use genetic methods that target a few specific genes both for studies of selectively neutral genetic variation (that is expected to be shaped mainly by mutation, gene flow, and genetic drift) and for studies of adaptive molecular evolution of genes expressed on the surfaces of sperm and eggs that mediate mate choice and reproductive success (and are expected to be shaped mainly by natural selection and sexual selection). The limitations of these targeted gene methods, and the availability of next-generation DNA sequencing methods, have led to an interest in expanding this work to use genomic approaches. Sequences of whole genomes or transcriptomes will allow us to generate very large numbers of DNA sequence alignments for selectively neutral markers (for much more accurate estimates of gene flow, genetic drift, and other demographic parameters that depend on sampling widely across the genome) and will allow us to discover additional genes expressed on the surfaces of sperm and eggs (for a better understanding of the ways in which species differences in sex and reproduction affect adaptive molecular evolution). One project I am pursuing now uses multiple ovary and testis transcriptomes to analyze both selectively neutral and adaptive molecular evolution in the context of a recently discovered zone of incipient speciation between northern and southern populations of a British Columbia sea star. The transcriptome data sets use the Illumina HiSeq platform, which generates hundreds of millions of short DNA sequence reads. A major bottleneck in my analysis of this project is the efficient processing and analysis of the sequence data and comparisons of the transcriptomes among different individual sea stars from northern and southern populations. I am currently (March-May 2012) participating in an IRMACS-sponsored workshop on introductory bioinformatics methods led by Richard Bruskiewich (and facilitated by Brian Corrie). An important specific product of this workshop for me will be learning to use the Galaxy Bioinformatics Workbench. I am applying to host my project at IRMACS in order to gain access to IRMACS computational resources for running Galaxy bioinformatics analyses via the Westgrid allocation to IRMACS.