Parasites are ubiquitous, abundant, and functionally significant components of ecosystems. Parasites and the diseases they cause can have deleterious effects on organisms at all scales of biological organization. Avian haemosporidians (genera Plasmodium and Haemoproteus) are a diverse group of vector-borne blood parasites that affect bird populations globally, with epidemic mortalities in Hawaiian and New Zealand birds. However, we still lack an understanding of avian haemosporidian infection dynamics in the Western Ghats, a global biodiversity hotspot, in India. This mountain chain is topographically complex, hosts one of the most globally isolated Sky Island systems and harbors remarkable bird diversity, with many endemic and threatened bird species. Here, I examined for the first time, eco-evolutionary factors affecting avian haemosporidian dynamics in the Western Ghats Sky Island system. Specifically, I elucidated diversity, host range, phylogeography and community structure of avian haemosporidians. I also tested the utility of novel genomic tools using sequence capture approach to advance parasite genomics and comparative phylogenomics.
My dissertation research revealed several novel haemosporidian parasite lineages endemic to the Western Ghats. Haemoproteus lineages were host specialists and co-speciated with their bird hosts whereas Plasmodium were generalists. Community structure of Haemoproteus was more affected by host phylogeny/ecology whereas Plasmodium were affected by geographic barriers, potentially leading to greater likelihood of emergence by Plasmodium in novel host communities. Variation in infection risk among bird communities was affected by host ecological traits promoting parasite exposure (e.g., sociality, foraging strata) and traits associated with host susceptibility (e.g., sexual dimorphism, body condition). Additionally, host phylogeny contributed substantially in predicting Haemoproteus infection risk compared to Plasmodium, reiterating that host ecology and host phylogeny together influence infection dynamics. Overall, my dissertation research provides novel insights into how geographical barriers, host (e.g. host phylogeny/ecology) and parasite (e.g. host specificity) factors influence avian haemosporidian dynamics. This has broad implications for understanding disease dynamics in natural populations and important from wildlife health perspective. In my final chapter, I demonstrated that sequence capture is a promising approach to obtain high-quality parasite genomic data and gain unique insights into the evolution of avian haemosporidians, an exciting advancement in avian haemosporidian research.
My dissertation research revealed several novel haemosporidian parasite lineages endemic to the Western Ghats. Haemoproteus lineages were host specialists and co-speciated with their bird hosts whereas Plasmodium were generalists. Community structure of Haemoproteus was more affected by host phylogeny/ecology whereas Plasmodium were affected by geographic barriers, potentially leading to greater likelihood of emergence by Plasmodium in novel host communities. Variation in infection risk among bird communities was affected by host ecological traits promoting parasite exposure (e.g., sociality, foraging strata) and traits associated with host susceptibility (e.g., sexual dimorphism, body condition). Additionally, host phylogeny contributed substantially in predicting Haemoproteus infection risk compared to Plasmodium, reiterating that host ecology and host phylogeny together influence infection dynamics. Overall, my dissertation research provides novel insights into how geographical barriers, host (e.g. host phylogeny/ecology) and parasite (e.g. host specificity) factors influence avian haemosporidian dynamics. This has broad implications for understanding disease dynamics in natural populations and important from wildlife health perspective. In my final chapter, I demonstrated that sequence capture is a promising approach to obtain high-quality parasite genomic data and gain unique insights into the evolution of avian haemosporidians, an exciting advancement in avian haemosporidian research.