Graduate Thesis Or Dissertation


Haemosporidian Infection Dynamics and Immune Gene Variation in a Population of Hybridizing Chickadees Public Deposited
  • Parasites are a complex and diverse group of organisms that have long intrigued researchers due to their spectrum of host specialization. Similarly, the consequences that parasites can impose on hosts also exhibit variation ranging from inconsequential to severe, with direct effects on fitness. Host-parasite interactions that are highly consequential can play a significant role in shaping host species evolutionary histories. Infectious outbreaks, and the lifespan of the organisms they directly impact, are a flicker along the timescale of evolutionary history, but the effects of these events can live on in genomes for millennia. One tool that researchers can use to investigate questions about evolutionary pattern and process are natural hybrid zones, regions where species overlap in their range and reproduce offspring of mixed ancestry. The focus of my dissertation is on the potential role of parasites in shaping host species barriers within natural hybrid zones and on understanding how this can translate to host genome evolution. I first conduct a review of the literature where I introduce a novel framework for thinking about parasites and how they might shape host species barriers in animal host systems. My third and fourth chapters are both an examination of haemosporidian parasites (Plasmodium, Leucocytozoon, and Haemoproteus) in a sympatric population of two songbird species–– the black-capped (Poecile atricapillus) and mountain (Poecile gambeli) chickadee. First, I report on an invasive Plasmodium parasite that is infecting this population of chickadees, with some thoughts on the ecology and evolution underlying parasite range expansions. I then systematically characterize the haemosporidian communities infecting this chickadee population and compare their divergent infection dynamics. These infection dynamics can influence species barriers and subsequently host genome evolution. I therefore focus my fifth chapter on understanding the evolution of the songbird genus, Poecile, with a focus on their immune genes. The findings of this work suggests both historic and ongoing introgression amongst Poecile species, with potential selection on immune genes in two Poecile hybrid zones. Through this dissertation I aimed to harness the investigative power of natural hybrid zones to explore host evolution as it is shaped by parasitism.

Date Issued
  • 2022-07-26
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Last Modified
  • 2022-09-16
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