Date of Award

2022

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biology

Abstract

Host-parasite interactions play a significant role in the comprehension of co-evolutionary mechanisms such as the host-parasite arms race. Those co-evolutionary mechanisms allow a better understanding of the parasite distribution, emergence of zoonotic diseases, and the impact on hosts populations. In this Ph.D.dissertation, I study the interaction between haemosporidian parasites ( Plasmodium, Haemoproteus , and Leucocytozoon ) and a polymorphic species, the white-throated sparrow ( Zonotrichia albicollis ). First, I examined the occurrence of haemosporidian parasites in a breeding population of white-throated sparrows in the Adirondacks, NY, and assessed their parasite diversity. Then, I evaluated the landscape and individual characteristics influencing the haemosporidian infection in that population. Finally, I investigated the impact of haemosporidian infection on the direct and indirect fitness of the birds. I found a high Plasmodium diversity with a lower Leucocytozoon and Haemoproteus diversity in the sampled bird, with parasite lineages found primarily in North and South America migratory birds. The Plasmodium - Leucocytozoon co-infection is influenced by habitat and individual characteristics, with bog habitat, age, and females increasing the likelihood of acquiring co-infection. Furthermore, individuals with a higher parasitemia are more likely to get co-infected with Plasmodium and Leucocytozoon . The Plasmodium-Leucocytozoon co-infection positively affects the white-throated sparrow reproductive success by increasing the nestling body condition. In contrast, a high haemosporidian parasitemia has a dissimilar effect on males and females, being detrimental for females with a reduction of extra-pair paternity leading to a reduction of nestling genetic diversity. While for males, high parasitemia might trigger a switch in reproductive investment with heavier nestlings and a higher ratio of genetic offspring belonging to the social father. Overall, I show an intricate relationship between hosts and parasites constantly evolving.

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