Population genomics of Drosophila suzukii reveal longitudinal population structure and signals of migrations in and out of the continental United States

Authors: LEWALD, KYLE - University Of California, Davis; ABRIEUX, ANTOINE - University Of California, Davis; WILSON, DEREK - University Of California, Davis; LEE, YOOSOOK - University Of Florida; ANDREAZZA, FELIPE - Universidade Federal De Vicosa; BEERS, ELIZABETH - Washington State University; BURRACK, HANNAH - North Carolina State University; DAANE, KENT - University Of California; DIEPENBROCK, LAUREN - University Of Florida; DRUMMOND, FRANCIS - University Of Maine; FANNING, PHILIP - University Of Maine; GAFFNEY, MICHAEL - Teagasc (AGRICULTURE AND FOOD DEVELOPMENT AUTHORITY); HESLER, STEPHEN - Cornell University; IORIATTI, CLAUDIO - Fondazione Edmund Mach; ISAACS, RUFUS - Michigan State University; LITTLE, BRIAN - University Of Georgia; LOEB, GREGORY - Cornell University; MILLER, BETSY - Oregon State University; NAVA, DORI - Embrapa Clima Temperado; RENDON, DALILA - Oregon State University; SIAL, ASHFAQ - University Of Georgia; DA SILVA, CHERRE - Embrapa; Stockton, Dara; VAN TIMMEREN, STEVEN - Michigan State University; WALLINGFORD, ANNA - University Of New Hampshire; WALTON, VAUGHN - Oregon State University; Wang, Xingeng; ZHAO, BO - University Of California; ZALOM, FRANK - University Of Florida; CHIU, JOANNA - University Of California

Submitted to: G3, Genes/Genomes/Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/10/2021
Publication Date: 10/2/2021
Citation: Lewald, K.M., Abrieux, A., Wilson, D.A., Lee, Y., Andreazza, F., Beers, E.H., Burrack, H.J., Daane, K., Diepenbrock, L., Drummond, F., Fanning, P.D., Gaffney, M., Hesler, S.P., Ioriatti, C., Isaacs, R., Little, B.A., Loeb, G.M., Miller, B., Nava, D., Rendon, D., Sial, A.A., da Silva, C., Stockton, D.G., Van Timmeren, S., Wallingford, A., Walton, V.M., Wang, X., Zhao, B., Zalom, F.G., Chiu, J. 2021. Population genomics of Drosophila suzukii reveal longitudinal population structure and signals of migrations in and out of the continental United States. G3, Genes/Genomes/Genetics. 11(12). Article jkab343. https://doi.org/10.1093/g3journal/jkab343.
DOI: https://doi.org/10.1093/g3journal/jkab343

Interpretive Summary: To understand the movement, dispersal, and diversity of invasion events by Spotted-wing Drosophila, a research team at UC Davis, led by Joanna Chiu, has sequenced and analyzed the genomes of over 200 flies collected in the US, Europe, South America, and Asia. The results show that within the US, there are distinct populations in the Eastern versus Western parts of the country, however within those areas population overlaps suggest continuing movement North and South. The implications of these data for understanding overwintering biology remain unclear although it supports the hypothesis that at least some of the yearly populations found in northern regions comes from annual migrations, either through natural migration events or due to human movement. The results also show a high level of diversity in the genome in the United States, which suggests invasion events from originating Asian sources may be ongoing or there was a very large original invasion event. In contrast, Europe's genetic diversity of SWD is much lower, suggesting limited recurrent invasion events and relative population stability. These data are useful for understanding the level of invasion risk still present in the U.S. and the degree of ongoing movement.

Technical Abstract: Drosophila suzukii, or spotted wing drosophila, is now an established keystone pest in many parts of the world, causing serious agricultural damage to the fruit crop industry. Native to East Asia, D. suzukii infestations have appeared on both East and West Coasts of the United States, occupying a wide range of climates. To efficiently control this pest, knowledge of past migration events, population structure, and genetic diversity is needed. To improve on previous studies examining genetic structure of D. suzukii, we sequenced whole genomes of 237 individual flies collected across the continental U.S., as well as several representative sites in Europe, Brazil, and Asia, to identify hundreds of thousands of genetic markers for analysis. We analyzed these markers to detect population structure, migration events, and estimate genetic diversity and differentiation within and between continents. We observe strong population structure between West and East Coast populations of the U.S., but no evidence of any population structure North to South, suggesting there is no broad-scale adaptations occurring in response to the large differences in regional winter temperatures. We also find evidence that repeated migration events from Asia into North America have provided increased levels of genetic diversity, which does not appear to be the case for Brazil or Europe. This large genomic dataset will spur future research in genomic adaptations underlying D. suzukii pest activity and development of novel control methods for this agricultural pest.