Micro‐ and macroparasite species richness in birds: The role of host life history and ecology

Abstract

Identifying the factors shaping variation in parasite diversity among host species is crucial to understand wildlife diseases. Although micro‐ and macroparasites may exert different selective pressures on their hosts, studies investigating the determinants of parasite species richness in animals have rarely considered this divide. Here, we investigated the role of host life history and ecology in explaining the species richness of helminths (macroparasites) and haemosporidians (microparasites) in birds world‐wide. We collated data from multiple global datasets on diverse bird traits (longevity, body mass, coloniality, migration distance/tendency, geographic range size and dietary and habitat breadths) and the species richness of their helminth and haemosporidian parasites. We tested predictors of helminth and haemosporidian parasite richness using phylogenetic generalized linear mixed models in a Bayesian framework. We found that, after controlling for research effort and host phylogeny, the richness of helminths, but not of haemosporidians, increased with host longevity, range size, migration distance and dietary breadth. Overall, these correlates were also important across different helminth groups (acanthocephalans, cestodes, nematodes and trematodes), and two additional ones (body mass, coloniality) emerged as important for cestodes and acanthocephalans. We propose that long life spans may promote the diversity of helminth parasite assemblages over evolutionary time, thus resulting in richer helminth faunas. Similarly, longer‐distance migrations, larger ranges and broader dietary breadths are likely to lead to greater encounter rates and the accumulation of trophically transmitted helminths. In contrast, vector‐borne haemosporidians may be influenced more by factors related to vector ecology than by the host traits included in the analyses. The lack of strong associations between haemosporidian species richness and host characteristics emphasizes the need to find appropriate traits to model the distribution and diversity of parasites with different environmental preferences in order to anticipate disease emergence risks associated with global change.

Host Cognition and Parasitism in Birds: A Review of the Main Mechanisms

“…Ecological generalists are often characterized by their higher cognitive abilities (e.g., larger brain or higher innovation rates; Overington et al, 2011;Ducatez et al, 2015). Because occurring in a wider diversity of habitats or exploiting a higher diversity of foods is likely to increase the diversity of parasites a given organism is exposed to (e.g., Gutiérrez et al, 2017Gutiérrez et al, , 2019, the generalist lifestyle of organisms with higher cognitive abilities should increase the rate of parasitism.…”

Wetter climates select for higher immune gene diversity in resident, but not migratory, songbirds

“…However, we found that the relationship between precipitation and number of MHC-I alleles remained significant after controlling for all three , table S7). We did, however, observe a marginal trend for species with larger ranges to have individuals with more MHC-I alleles (PM = 0.0001, CI = 0.0000 to 0.0003, pMCMC = 0.07; electronic supplementary material, figure S6 and table S7), but this may be due to species with larger ranges encountering more pathogens [55]. The lack of evidence for demographic effects is perhaps not surprising, given that genes under balancing selection, such as MHC genes, have been shown to maintain diversity even through demographic events that reduce genome-wide diversity [42,44,56,57].…”

Migrant birds disperse haemosporidian parasites and affect their transmission in avian communities

“…The introduction of pathogens by migrants to new localities might lead to changes to the local community structure or richness, depending on the susceptibility of resident species to infection (Altizer et al 2011). Indeed, recent studies have demonstrated that migratory birds harbor a greater diversity of parasites than resident species (Koprivnikar and Leung 2015, Gutiérrez et al 2019) and documented the influence of migratory birds on the spread of important pathogens (Morshed et al 2005, Hellgren et al 2007, Ricklefs et al 2017) with some of these able to infect humans (Morshed et al 2005, Poupon et al 2006, Lindeborg et al 2012). Thus, the migratory behavior of birds may directly influence host local richness and community structure, as well as the local richness of parasite species.…”