Bird Community Composition, Migration, and Environmental Factors Jointly Influence the Global Distribution of Avian Haemosporidian Lineages

Parasite distributions are under the influence of host occurrence and tolerable environmental conditions. In vector-borne disease systems, including avian malaria, they are further constrained by the environmental niche of the vectors. The fact that avian haemosporidians occur in a large number of migratory and non-migratory species means the role of bird migration in the global distribution of avian haemosporidians is an open question. Because avian haemosporidians refer to a large number of genetic lineages that are well characterized in terms of host and geographic range, we introduce an ecoregion pairwise analysis that sets out to explain the similarity in lineages in pairs of ecoregions as a function of the pair's similarity in migratory and non-migratory bird communities, as well as environmental conditions. We identify important roles for each of these factors in explaining the overall geographic distribution of lineages, including strong support for the role of migratory birds in moving lineages between environmentally dissimilar ecoregions.