Document Type

Dissertation

Degree

Doctor of Philosophy

Major

Biology

Date of Defense

2-26-2018

Graduate Advisor

Dr. Patricia Parker

Committee

Dr. Kathryn Huyvaert

Dr. Robert Ricklefs

Dr. Sebastian Tello

Abstract

The large number of emergent infectious diseases witnessed in the past few decades has increased interest in the ecology and distribution of potentially threatening pathogens worldwide. Island species are often considered more vulnerable to parasites due to their impoverished parasite communities, long isolation from disease and low genetic diversity. Avian surveys done by our group on the Galapagos Islands have found various pathogens infecting their endemic avifauna, including haemosporidian parasites of the genera Plasmodium and Haemoproteus. My research seeks to understand the relationships between two haemosporidian parasites (blood parasites) and their multiple bird hosts in Galapagos and to explore the immune system of insular birds. A three island survey was implemented along an altitudinal gradient between June 2013 and July 2015, to collect blood and plasma samples from 25 species of endemic and introduced birds. We explored patterns of Haemoproteus multipigmentatus infection in passeriform birds that provided evidence of parasite spillover events from Galapagos doves to passerines. We investigated the possibility that introduced birds in the archipelago were reservoir hosts for Plasmodium sp. But, contrary to our expectations, we found no evidence to suggest introduced birds are implicated in haemosporidian transmission or maintenance. We used a site-occupancy approach to obtain informed and more precise estimates of prevalence for both parasites and the ecological factors influencing variation, to improve assessments of disease risk for the endemic avifauna. And lastly, we investigated the relationship between a species’ time of arrival to the archipelago and strength of the immune response. We found no general trend, among six indexes of immune response, to indicate that species that arrived to the islands earlier have a weaker immune system function than more recent arrivals. Collectively, our research demonstrates the importance of community wide surveys to identify or dismiss possible agents and factors of disease, to understand host-parasite dynamics and to better assess the disease risks faced by wildlife.

Available for download on Thursday, May 02, 2019

Share

COinS