Abstract
Biological invasions carry substantial practical and scientific importance, and represent natural evolutionary experiments on contemporary timescales. Here, we investigated genomic diversity, invasion history, and environmental adaptation of the crop pest Drosophila suzukii using whole-genome sequencing data and environmental metadata for 29 population samples from its native and invasive range. Our analysis of genome-wide variation revealed maximal diversity in a population from eastern China, with other populations largely containing a subset of the genetic diversity present in this sample, consistent with an ancestral or refugial species range encompassing this region of Asia. Our analyses of genomic diversity and population history recapitulated some previously suggested dynamics of genetic structure, invasion bottlenecks, and admixture events. However, we suggest that clearer inferences of the geographic origins of worldwide invasions will require denser geographic sampling of genetic variation, particularly in Asia. Using a genome-environment association approach, we detected genetic signals of local adaptation associated with nine distinct environmental factors related to altitude, wind speed, precipitation, temperature, and human land use. We detected some unique functional signatures for each environmental variable, such as a prevalence of cuticular genes associated with annual precipitation. We also inferred biological commonalities in the adaptation to diverse selective pressures, particularly in terms of the apparent contribution of nervous system evolution to enriched processes (ranging from neuron development to circadian behavior) and/or top genes associated with all nine environmental variables. Our findings provide insights into the invasion history of D. suzukii and depict a finer-scale adaptive landscape underlying this species’ invasion success.
Competing Interest Statement
The authors have declared no competing interest.
