Ecology and evolution of host-parasite interactions

Introduced parasites can have dire consequences for naive hosts. But how do these interactions reciprocally shape species’ ecology and evolution over long periods of time? We collaborate with Chris Witt’s lab at the University of New Mexico and the Museum of Southwestern Biology to answer this question.

The importance of specimen-based research

Museums collections are an essential part of studying biology in a changing world. Specimens provide a snapshot into the organisms that were present at a certain place and time. This record can be used for future studies that are both planned and unknown at the time of collection. For instance, specimen collectors a hundred years ago had no idea that their specimens could be used today to study genetic relationships of organisms. The “extended specimen” today includes information not just about the individual organism, but also about the entire community of parasites and pathogens living with the host. We are using bird specimens to study the diverse community of blood (malaria) parasites found in Peru.

Host susceptibility is conserved over evolutionary time

We screened ~4000 birds in the Peruvian Andes for blood parasite infection and used the resulting dataset to investigate patterns of prevalence among avian clades. Many different factors may contribute to susceptibility to infection: hosts with similar ecology, with similar behaviors, or similar phylogenetic histories may have common patterns in infection. We used a Bayesian phylogenetic modeling framework to identify the factors that most predict variation in susceptibility. We found evidence for deeply conserved variation in susceptibility across the avian tree, suggesting that conserved variation in defenses against parasites contribute to variation in host susceptibility to parasites (Barrow, McNew et al. 2019).

Biotic and abiotic factors structure communities of hosts and parasites

We then used the same dataset to identify what processes drive change (turnover) in communities of birds and haemosporidians in the Andes. We compared the contributions of habitat filtering, barriers to dispersal, and host-parasite interactions in shaping community composition. Bird communities are largely shaped by abiotic factors of precipitation and temperature, while parasite communities are shaped by both precipitation and the available host community. These patterns are complex over space and time so for more details check out our paper here and explore bird richness and turnover data here and here!