Resource predictability and specialization in avian malaria parasites

Abstract

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.

Consistent patterns of high alpha and low beta diversity in tropical parasitic and free‐living protists

“…Plasmodium (Fecchio et al, 2017;Svensson-Coelho, Loiselle, Blake, & Ricklefs, 2016), which accounted for only a small fraction of Apicomplexa here. The cercozoan and ciliophoran patterns within forests suggest that their OTU diversity is driven by environmental filtering.…”

“…The apicomplexan patterns can be explained by them mirroring the patterns of their animal hosts: Arthropod biogeographic patterns, at least for the herbivores, are themselves partially driven by their host plants (Basset et al., ; Novotny et al., ). Apicomplexan patterns should follow the animals if they are largely host‐specific, although little is known of their biology in the Neotropics except for some Haemospororida, such as Plasmodium (Fecchio et al., ; Svensson‐Coelho, Loiselle, Blake, & Ricklefs, ), which accounted for only a small fraction of Apicomplexa here. The cercozoan and ciliophoran patterns within forests suggest that their OTU diversity is driven by environmental filtering.…”

Integrating phylogenetic and ecological distances reveals new insights into parasite host specificity

“…; but see Svensson‐Coelho et al . ). Moreover, little is known about the phylogenetic dispersion of avian malaria parasites carried by individual host species, despite the fact that birds are commonly thought to acquire new parasites and leave others behind as their ranges expand and contract (Ricklefs et al .…”

“…For example, a wide diversity of bat species are susceptible to white nose syndrome, yet infection is often restricted to species that use similar hibernation sites that are more favourable to the pathogen (Zukal et al 2014). However, while host specificity is commonly quantified in avian malaria research, inferences have to date relied on specificity indices that ignore host ecological attributes (Ewen et al 2012;Moens & P erez-Tris 2015;Olsson-Pons et al 2015; but see Svensson-Coelho et al 2016). Moreover, little is known about the phylogenetic dispersion of avian malaria parasites carried by individual host species, despite the fact that birds are commonly thought to acquire new parasites and leave others behind as their ranges expand and contract (Ricklefs et al 2004;Lauron et al 2014).…”

Persistent patterns of high alpha and low beta diversity in tropical parasitic and free-living protists

“…The apicomplexan patterns can be explained by them mirroring the patterns of their animal hosts: arthropod biogeographic patterns, at least for the herbivores, are themselves partially driven by their host plants (Basset et al 2015, Novotny et al 2007). Apicomplexan patterns should follow the animals if they are largely host-specific, although little is known of their biology in the Neotropics except for some Haemospororida, such as Plasmodium (Fecchio et al 2017, Svensson-Coelho et al 2016, which accounted for only a small fraction of Apicomplexa here. The cercozoan and ciliophoran patterns within forests suggest that their OTU diversity is driven by environmental filtering, while their phylogenetic diversity is structured by spatially-related processes, at least partially; similar patterns were also observed for Neotropical trees within forests .…”