258T Poster - Population Genetics
Thursday June 09, 8:30 PM - 9:15 PM

Authors:
Siyuan Feng ¹; Samuel DeGrey ²; Sean Schoville ²; John Pool ¹

Affiliations:
1) Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI; 2) Department of Entomology, University of Wisconsin-Madison, Madison, WI

Keywords:
Population history

Biological invasions are of great research interest as they often carry significant economic and ecological costs, but also constitute natural experiments that allow investigations of evolutionary processes on contemporary timescales. The fruit pest Drosophila suzukii, which has rapidly invaded the globe within the past few decades, stands out as an excellent model for studying invasion genomics and local adaptation owing to its occupation of distinct environments. However, despite the recent availability of genomic resources in D. suzukii, inference of the invasion route has only been made based on limited microsatellite markers. Here, we investigated genomic diversity and invasion history of D. suzukii using whole- genome sequencing data from 29 population samples from four distant continents and three islands. Strong founder event bottlenecks were suggested by the acute drop in nucleotide diversity of invasive populations relative to observed diversity in the native range (including China and Japan), with effectively longer bottlenecks on the X chromosome due to its smaller effective population size. Principal component analysis of allele frequency and matrices of window F_ST and D_XY recapitulated the expected clustering of distinct native, European and American populations. All other populations were found to have a subset of the genetic diversity present in a sample from southeastern China (Ningbo), consistent with an ancestral or refugial species range in this region of Asia. A hierarchical population structure predicted by maximum-likelihood tree supported that inference, and also suggested separate Asia-sourced invasion events into America and Europe. Further tree-based admixture inference predicted gene flow among continents following the first founder events. To detect genomic targets of local adaptations under specific environmental pressure, we are now performing genome-wide environment association analysis between SNPs and selected uncorrelated environmental variables at sampled locations. Our findings provide insights into the population history of D. suzukii, and have the potential to further our understanding of the genetic architecture underlying this species’ invasion success.