Evidence for evolutionary change in invasive populations of Drosophila suzukii in Hawai‘i

Authors: KOCH, JONATHAN - University Of Hawaii; DUPUIS, JULIUS - University Of Hawaii; JARDELEZA, MARCEL-KATE - University Of Hawaii; OUEDRAOGO, NADIATOU - University Of Hawaii; Geib, Scott; Follett, Peter; PRICE, DONALD - University Of Hawaii

Submitted to: Biological Invasions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/6/2020
Publication Date: 2/12/2020
Citation: Koch, J.B., Dupuis, J.R., Jardeleza, M., Ouedraogo, N., Geib, S.M., Follett, P.A., Price, D.K. 2020. Evidence for evolutionary change in invasive populations of Drosophila suzukii in Hawai‘i. Biological Invasions. 22:1753-1770. https://doi.org/10.1007/s10530-020-02217-5.
DOI: https://doi.org/10.1007/s10530-020-02217-5

Interpretive Summary: When an invasive species arrives in a novel environment, one of the most interesting evolutionary questions is “how does this species adapt to a novel environment and how fast does that happen?”. Here we use population genomics to address that question in the spotted wing Drosophila fly, which invaded Hawaii ~38 years ago. We find very weak population structure in the dataset, indicating 1) that it was likely a single introduction of flies to the islands and 2) we are viewing the early stages of neutral genetic differentiation between isolated populations.

Technical Abstract: In the context of evolutionary theory, invasion biology provides a fantastic enigma: how does a species with limited standing genetic variation survive and adapt to a novel environment? Reduced genetic diversity is typically associated with low fitness and evolutionary potential, yet invasive species have proven to be successful competitors despite undergoing a genetic bottleneck during the early stages of colonization. Our goal in this study was to determine how a recent invader, Drosophila suzukii, has evolved in the Hawaiian archipelago since colonizing the islands in 1980. Wing phenotype analysis revealed that altitude was a significant predictor of wing size, with high altitude populations possessing larger wings than low altitude populations. While we discovered low genetic diversity and differentiation in all populations, three unique genetic clusters were detected with a model-free, multivariate statistical approach. We discovered 23 candidate loci under selection using two complementary analyses to detect FST outliers across the genome. For 12 of these loci predicted proteins are associated with Drosophila spp. chemosensation, amino acid and sodium ion transport, a Ras effector pathway, and cytidine deamination. Despite a genetic bottleneck, adventive D. suzukii populations are beginning to differentiate across the Hawaiian archipelago and selection for key behavioral and cellular processes are likely ongoing.