Genetic diversity and thermal performance in invasive and native populations of African fig flies

During biological invasions, alien populations can suffer losses of genetic diversity that are predicted to negatively impact their fitness/performance. Using genome sequences, we show that invasive populations of the African fig fly, Zaprionus indianus, have lower levels of genetic diversity compared to native populations, and that genetic diversity is lost more in regions of the genome with low recombination rates. However, genetic diversity remains as high or higher in invasive populations than in populations of non-invasive congeneric species. We then use parameter estimates from thermal performance curves measured for 13 species of Zaprionus to show that Z. indianus has the broadest thermal niche of measured species, and that performance does not differ between invasive and native populations. These results illustrate how aspects of genetic diversity in invasive species can be decoupled from measures of fitness, and that a broad thermal niche may have helped facilitate Z. indianus's range expansion.