E&E Fall 2021 Seminar Series:
Dr. David Clark
University of Pittsburgh - Stephenson Lab
"Elucidating the interplay between the ecology and evolution of a guppy host and Gyrodactylus parasite system"
Parasites are ubiquitous in nature; however not all interactions between hosts and their parasites are equal. The ecology and evolution of host-parasite interactions are intrinsically tied together. Differences in host ecology like sex, behavior, density, and resource acquisition can influence parasite population and evolutionary dynamics. Reciprocally, parasite ecology and evolution can feed back to influence host ecology. We use a guppy host (Poecilia reticulata) and monogenean flatworm parasite (Gyrodactylus spp.) system to assess how host ecology can drive changes in both parasite ecology and evolution, and how changes in parasite infection can in turn alter host ecology. First, we examined whether population-level differences in host ecology could drive variation in parasite distribution in those host populations. Parasites were less aggregated in populations containing hosts with larger body sizes: hosts in these populations were less likely to be uninfected, possibly because larger fish are better able to tolerate infection. We also found that parasites are less aggregated among male than female guppies. This pattern appears due to the fact that the most heavily infected hosts are ‘missing’ from our samples, particularly among males, potentially due to sex differences in tolerance. Indeed, in an experiment testing how parasite infection (parasite ecology) could drive differences in host activity (host ecology), we found that males on which parasites were growing fastest swam slowest, but there was no such effect among females. This finding suggests that males suffer more significant consequences of Gyrodactylus infection, in line with our aggregation results. Next, we will examine how changes in host behavior and resource level (host ecology) can shift selection pressures on the harm their parasites cause (virulence, parasite evolution). We will seed experimental epidemics among guppy populations varying in resource levels with multiple parasite strains and track changes in host behavior and parasite evolutionary change. Together, these projects build on our understanding of the interplay between the ecology and evolution of both host and their parasites, and how these can drive differences in the interaction between them.
Wednesday, October 6th, 2021
A219B Langley Hall
12:00 PM