Heidi Montgomery, University of Utah
Biology
Parasites are arguably the most diverse group of organisms on the planet. One key factor in determining patterns of parasite biodiversity is the number of host species a parasite can infect, or its host specificity. However, surprisingly very little is known about the evolution of host specificity. Here I use domesticated pigeons (Columba livia) and their ectoparasitic feather lice (Columbicola columbae) to demonstrate how parasite body size influences host use. The current study has two main goals: 1) to use different sized hosts to experimentally evolve louse body size, and 2) to determine how parasite body size effects host specificity. Four breeds of domesticated pigeons were infested with parasitic feather lice. After roughly six generations, mean louse body size changed with respect to host body size, with the largest pigeons having the largest lice. Interestingly, the smallest pigeons had larger lice as well. However, this increase in louse size appears to be the result of a change in microhabitat use, with lice shifting from predominantly the wings and tail to the head. This study is one of the first to experimentally demonstrate how changes in parasite morphology and behavior influence the evolution of host specificity.