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Parasites of the genera Plasmodium and Haemoproteus (Apicomplexa: Haemosporida) are a diverse group of pathogens that infect birds nearly worldwide. Despite their ubiquity, the ecological and evolutionary factors that shape the diversity and distribution of these protozoan parasites among avian communities and geographic regions are poorly understood. Based on a survey throughout the Neotropics of the haemosporidian parasites infecting manakins (Pipridae), a family of Passerine birds endemic to this region, we asked whether host relatedness, ecological similarity and geographic proximity structure parasite turnover between manakin species and local manakin assemblages. We used molecular methods to screen 1343 individuals of 30 manakin species for the presence of parasites. We found no significant correlations between manakin parasite lineage turnover and both manakin species turnover and geographic distance. Climate differences, species turnover in the larger bird community and parasite lineage turnover in non-manakin hosts did not correlate with manakin parasite lineage turnover. We also found no evidence that manakin parasite lineage turnover among host species correlates with range overlap and genetic divergence among hosts. Our analyses indicate that host switching (turnover among host species) and dispersal (turnover among locations) of haemosporidian parasites in manakins are not constrained at this scale.

We tested the hypothesis that avian haemosporidian (malaria) parasites specialize on hosts that can be characterized as predictable resources at a site in Amazonian Ecuador. We incorporated host phylogenetic relationship and relative abundance in assessing parasite specialization, and we examined associations between parasite specialization and three host characteristics - abundance, mass and longevity - using quantile regression, phylogenetic logistic regression and t-tests. Hosts of specialist malaria parasite lineages were on average more abundant than hosts of generalist parasite lineages, but the relationship between host abundance and parasite specialization was not consistent across analyses. We also found support for a positive association between parasite specialization and host longevity, but this also was not consistent across analyses. Nonetheless, our findings suggest that the predictability of a host resource may play a role in the evolution of specialization. However, we also discuss two alternative explanations to the resource predictability hypothesis for specialization: (i) that interspecific interactions among the parasites themselves might constrain some parasites to a specialist strategy, and (ii) that frequent encounters with multiple host species, mediated by blood-sucking insects, might promote generalization within this system., (© 2016 John Wiley & Sons Ltd.)

How specialization of consumers with respect to resources varies with respect to latitude is poorly understood. Coexistence of many species in the tropics might be possible only if specialization also increases. Alternatively, lower average abundance of more diverse biotic resources in the tropics might force consumers to become more generalized foragers. We examine levels of reciprocal specialization in an antagonistic system-avian malaria-to determine whether the number of host species used and/or parasite lineages harbored differ between a temperate and a tropical assemblage. We evaluate the results of network analysis, which can incorporate both bird and parasite perspectives on specialization in one quantitative index, in comparison to null models. Specialization was significantly greater in both sample sites than predicted from null models. We found evidence for lower per-host species parasite diversity in temperate compared to tropical birds. However, specialization did not differ between the tropical and temperate sites from the parasite perspective. We supplemented the network analysis with estimates of specialization that incorporate phylogenetic relationships of associates and found no differences between sites. Thus, our analyses indicate that specialization within an antagonistic host-parasite (resource-consumer) system varies little between tropical and temperate localities.