Adaptive tracking contributes to the invasion success of a global pest insect

Invasive species are a threat to biodiversity, natural resources, and the economy. Preventing future invasions requires the ability to predict which species will be successful invaders. Invading a new region often requires coping with novel environmental conditions, yet how invading populations adapt to environmental conditions encountered in their introduced range is not always clear. One process that may facilitate invasion in temperate environments is seasonal adaptive tracking, a rapid evolutionary process in which allele frequencies and phenotypes shift in response to seasonal environmental fluctuations, promoting the long-term maintenance of polymorphisms. Here, we test the hypothesis that adaptive tracking is a key contributor to the invasion success of the globally invasive fly Drosophila suzukii. We demonstrate that adaptive tracking results in predictable, rapid evolution of a key thermal tolerance trait (critical thermal minimum) essential for coping with climate variability. We also detect adaptive tracking in several genomic regions enriched for seasonally fluctuating alleles, and these alleles map to loci implicated in diverse traits, including thermal tolerance, pesticide resistance, and olfactory behavior. Finally, we find that loci undergoing adaptive tracking are significantly enriched for alleles associated with invasion in North American populations, suggesting that rapid evolution of seasonal traits may contribute to the success of this invasive species.