The effect of genotype on avian malaria infections in the Amur falcon (Falco amurensis)

Abstract

Avian malaria is caused by haemosporidian parasites (Plasmodium, Haemoproteus and Leucocytozoon) that are transmitted by dipteran vectors. Passerines have been the focus of avian malaria research however raptors are generally keystone species in ecosystems making them important hosts to investigate. The Amur falcon (Falco amurensis) is a small raptor with the longest migration recorded in any raptor species. This host is particularly interesting to investigate as although it is a raptor it belongs to the order Falconiforms which ultimately is more closely related to parrots and passerines compared to other raptors. The falcons congregate in large flocks during migration which may impact the infection rate of the parasites. The Amur falcon has had a depletion in numbers due to mass harvesting in 2012 as well as two hailstorms that killed approximately 1000 falcons in Kwa-Zulu Natal, South Africa, making it a novel host to test for bottleneck events as well as genetic diversity and population structure. The main aim of this thesis was to determine the significance of age, sex and individual heterozygosity on avian malaria infections in the Amur falcon. The results of this study indicated that the Amur falcon had a high rate of haemosporidian parasite infection, particularly Haemoproteus. Phylogenetic analyses indicated that Haemoproteus was host specific while Leucocytozoon was found to be more generalist, infecting many different species of birds. The Amur falcon population had high genetic diversity and low levels of inbreeding indicating a healthy population. There was a lack of population structure. Generalized linear models were used to test whether sex (male or female), age (juvenile or adult) and individual heterozygosity were drivers of avian malaria infection in the Amur falcon. No significant associations were found except when the different lineages of Haemoproteus were considered independently. The data and results presented in this thesis provide a baseline for future studies on the Amur falcon, and also contributes towards a growing body of work examining haemosporidian parasite infections in migratory birds.