Phylogenetic uniqueness, not latitude, explains the diversity of avian blood parasite communities worldwide

Abstract

Aim: Characterizing macroecological patterns in biodiversity is key to improve our understanding of community assembly. Global biodiversity for many taxa follows a latitudinal gradient, with increased diversity in tropical latitudes. Less is known about global parasite biodiversity, inhibiting our ability to predict how global change will impact parasitic disease emergence. Using distribution and phylogenetic data for 2,386 avian haemosporidian blood parasites (genera Plasmodium, Haemoproteus and Leucocytozoon), I assessed how contemporary and historical drivers influence the composition of parasite communities worldwide. Location: Global. Time period: Current. Major taxa studied: Haemosporidian blood parasites. Methods: Parasite distribution and cytochrome b sequence data were accessed from an open-source database. Bayesian phylogenetic tree distributions were constructed for each parasite genus using two substitution models to capture uncertainty. Hierarchical regressions assessed effects of environmental variation, latitude and phylogenetic β-diversity (βdiv; a proxy for phylogenetic uniqueness) on the diversity and asymmetry of parasite communities around the globe. Results: I uncovered biodiversity hotspots and identified broad variation in global diversity patterns among parasite genera. Community diversity increased with increasing phylogenetic uniqueness for all three parasite genera; however, these diverse and unique regions did not consistently occur in the tropics. I found no evidence of a latitudinal diversity gradient, and support for a latitudinal gradient in community phylogenetic asymmetry was weak. Main conclusions: Global variation in avian haemosporidian phylogenetic diversity does not reflect a latitudinal gradient. Instead, parasite biogeography may reflect fundamental differences in host-switching tendencies or the timing of avian evolutionary radiations. Examining the interplay between shared evolutionary history and phylogenetic diversity can provide important insights into the drivers of parasite biodiversity at global scales.