Rapid wing size evolution of African fig fly (Zaprionus indianus) following temperate colonization

Invasive species often encounter novel selective pressures in their
invaded range, and understanding their potential for rapid evolution is
critical for developing effective management strategies. Zaprionus
indianus is an invasive drosophilid native to Africa that reached Florida
in 2005 and likely re-establishes temperate North American populations
each year. We addressed two evolutionary questions in this system: first,
do populations evolve phenotypic changes in the generations immediately
following colonization of temperate environments? Second, does Z. indianus
evolve directional phenotypic changes along a latitudinal cline? We
established isofemale lines from wild collections across space and time
and measured twelve ecologically relevant phenotypes, using a reference
population as a control. Z. indianus evolved smaller wings following
colonization, suggesting early colonizers have larger wings, but smaller
wings are favorable after colonization. No other phenotypes changed
significantly following colonization or across latitudes, but we did see
significant post-colonization changes in principal components of all
phenotypes. We documented substantial laboratory evolution and effects of
the laboratory environment across multiple phenotypes, emphasizing the
importance of controlling for both possibilities when conducting common
garden studies. Our results demonstrate the potential for rapid adaptation
in Z. indianus, which could contribute to its success and expansion
throughout invaded ecosystems.