Long-distance dispersal of pigeons and dove generated new ecological opportunities for host-switching and adaptive radiation by their parasites.

Adaptive radiation is an important
mechanism of organismal diversification, and can be triggered
by new ecological opportunities.
Although poorly studied in this regard, parasites are an ideal group in which to
study adaptive radiations because of their close associations with host species. Both experimental and comparative studies
suggest that the ectoparasitic wing lice of pigeons and doves have adaptively
radiated, leading to differences in body size and overall coloration. Here we show that long-distance dispersal by dove
hosts was central to parasite diversification because it provided new
ecological opportunities for parasites to speciate after host-switching. We further show that these new opportunities
for host-switching decreased over time, with cospeciation becoming the more
dominant mode of parasite speciation. Taken
together, our results suggest that host dispersal, followed by host-switching,
provided novel ecological opportunities that facilitated adaptive radiation by
parasites.