Title

Historical Biogeography, Spatial Distribution, and Within-Host Interactions of Avian Haemosporidian Parasites (Apicomplexa, Haemosporida)

Document Type

Dissertation

Degree

Doctor of Philosophy

Major

Biology

Date of Defense

12-9-2016

Graduate Advisor

Robert E. Ricklefs, PhD

Committee

Althof, Wolfgang

Patricia G Parker

Robert J Marquis

Michael E Hughes

Abstract

This dissertation addresses several aspects of the biogeography and evolution of avian malarial parasites (Haemosporida: Plasmodium and Haemoproteus), and the interactions of these pathogens with their hosts and other avian blood parasites. In Chapter 1, I investigate change in haemosporidian assemblages on the West Indies over millennial time scales, taking advantage of the historical isolation of islands by postglacial rising sea levels. I found that, the prevalence of parasite lineages is highly dynamic over periods from decades to thousands of years. Turnover of lineages requires more time than variation in lineage prevalence, suggesting that competitive exclusion of parasite lineages, likely involving evolution of host resistance, takes place over evolutionary time scales. In Chapter 2, I report the occurrence of the invasive and virulent avian malaria parasite, Plasmodium relictum, in the endemic Cuban avifauna. Targeting a region of the parasite’s merozoite surface protein gene, I determined that the P. relictum haplotype present in Cuba matches that of the malaria parasite that caused the population decline and extinction of endemic Hawaiian birds. I suggested a time frame for the introduction of this parasite lineage on Cuba, and hypothesize that avian malaria might be responsible for the absence from Cuba of several otherwise geographically widespread bird species in the West Indies. In Chapter 3, I compare parasite prevalence in wintering shorebirds in two areas in Argentina: marine habitats generally lacking dipteran parasite vectors, and the shorelines of an inland freshwater basin, where landbirds exhibiting high parasite prevalence, and dipteran vectors are present. I found that haemosporidian infections are rare in shorebirds, even when they are exposed to parasite transmission, suggesting that shorebirds are highly resistant to haemosporidian infections. In Chapter 4, I investigated the occurrence of co-infections between Plasmodium spp. and Trypanosoma spp. parasites in a population of yellow-breasted chats (Icteria virens) in southern Missouri. I determined that individuals infected with malaria parasites are more likely also to host trypanosome parasites, when compared to individuals free of infections. Overall, this dissertation supports hypotheses regarding the geographic and the host distribution of haemosporidian parasites, and how these distributions change over evolutionary periods of time.

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