Date of this Version
Hoppe, I. R. (2021) Social and ecological correlates of avian infection by haemosporidian blood parasites. MSc Thesis. University of Nebraska, Lincoln, Nebraska, USA.
Haemosporidian parasites are a significant source of morbidity and mortality for birds. There is growing recognition of the negative consequences of haemosporidian infections for wild birds at individual and population levels. Avian haemosporidians are geographically widespread, have been detected from a phylogenetically diverse array of hosts, and have been the focus of extensive research due to their impacts on birds and their similarity to vector-borne diseases of humans. However, factors influencing haemosporidian transmission, especially transmission between species, are poorly understood. To better understand these influences, we compared prevalence and diversity of haemosporidian blood parasite infections among species in a behaviorally and ecologically diverse host assemblage. We studied whether interspecific associations could explain community-wide trends in infection by pairing molecular diagnostics with direct observations of species interactions. Haemosporidian prevalence in the community was low (8.6%), but varied substantially with host phylogeny. Most (94.8% of all infections) infections were identified as Haemoproteus spp. Few Plasmodium spp. infections were detected, and no Leucocytozoon spp. infections were found. We found no evidence for an effect of interspecific sociality on Haemoproteus infections, but we did find evidence for an effect of intraspecific sociality. Individuals of species that had smaller average conspecific group sizes were more likely to be infected than those of species with larger groups. We also found that species with relatively long lifespans (as an index of immune investment) had higher prevalences than species with shorter lifespans. No other individual- or species-level traits were associated with Haemoproteus infection. We identified 7 Haemoproteus mitochondrial cytochrome b lineages, which clustered at the host family level. Two Plasmodium lineages were also identified, each of which had been previously detected in different host species in the region. The apparent host-family specificity of the parasite lineages may partly explain the lack of effect of interspecific sociality on Haemoproteus infection probability, and implies the presence of barriers to transmission that are associated with host phylogeny.
Advisor: Elizabeth VanWormer