Nematode parasite diversity in birds: the role of host ecology, life history and migration

Abstract

Previous studies have found that migratory birds generally have a more diverse array of pathogens such as parasites, as well as higher intensities of infection. However, it is not clear whether this is driven by the metabolic and physiological demands of migration, differential selection on host life-history traits or basic ecological differences between migratory and non-migratory species. Parasitic helminths can cause significant pathology in their hosts, and many are trophically transmitted such that host diet and habitat use play key roles in the acquisition of infections. Given the concurrent changes in avian habitats and migratory behaviour, it is critical to understand the degree to which host ecology influences their parasite communities. We examined nematode parasite diversity in 153 species of Anseriformes (water birds) and Accipitriformes (predatory birds) in relation to their migratory behaviour, diet, habitat use, geographic distribution and life history using previously published data. Overall, migrators, host species with wide geographic distributions and those utilizing multiple aquatic habitats had greater nematode richness (number of species), and birds with large clutches harboured more diverse nematode fauna with respect to number of superfamilies. Separate analyses for each host order found similar results related to distribution, habitat use and migration; however, herbivorous water birds played host to a less diverse nematode community compared to those that consume some animals. Birds using multiple aquatic habitats have a more diverse nematode fauna relative to primarily terrestrial species, likely because there is greater opportunity for contact with parasite infectious stages and/or consumption of infected hosts. As such, omnivorous and carnivorous birds using aquatic habitats may be more affected by environmental changes that alter their diet and range. Even though there were no overall differences in their ecology and life history compared with non-migrators, migratory bird species still harboured a more diverse array of nematodes, suggesting that this behaviour places unique demands on these hosts and warrants further study.

Your infections are what you eat: How host ecology shapes the helminth parasite communities of lizards

“…For example, Gregory et al (1991) found that bird species utilizing aquatic habitats have greater trematode (flukes) richness. Similarly, a recent study found that bird species across three orders which use aquatic habitat have greater nematode richness than species that do not (Leung & Koprivnikar, 2016).…”

“…In addition, recent studies with birds have demonstrated the importance of host diet and habitat use on the diversity of their helminth fauna (Gutiérrez et al, 2017;Leung & Koprivnikar, 2016). In addition, recent studies with birds have demonstrated the importance of host diet and habitat use on the diversity of their helminth fauna (Gutiérrez et al, 2017;Leung & Koprivnikar, 2016).…”

“…Following the approach of similar comparative analyses (Koprivnikar & Leung, 2015;Leung & Koprivnikar, 2016), we counted the number of unique endohelminth species for each host after considering taxonomic issues and those related to study bias (see Supporting Information). The body mass for each retained lizard species was additionally obtained from Feldman et al (2016) given that larger hosts may have more parasites (Gregory et al, 1996;Morand & Poulin, 1998;Kamiya et al, 2014, but see also Poulin, 1997), but host size may also be confounded with diet, habitat, and life-history traits.…”

“…It may be expected that a host's diet plays a key role in shaping its endohelminth community because many are acquired through ingestion of infective larval stages, either incidentally from the environment or from infected prey items which serve as intermediate or paratenic hosts, particularly considering that trophic transmission is required for many endohelminths (Lafferty, 1999;Poulin & Morand, 2004). While some studies have found host diet to influence helminth diversity (Choudhury & Dick, 2000;Gutiérrez, Rakhimberdiev, Piersma, & Thieltges, 2017;Leung & Koprivnikar, 2016;Lindenfors et al, 2007), that has not always been found to be the case (Gregory, Keymer, & Harvey, 1991;Poulin, 1995;Sasal, Morand, & Guégan, 1997).…”

Molecular identification and characterization of partial COX1 gene from caecal worm (Aulonocephalus pennula) in Northern bobwhite (Colinus virginianus) from the Rolling Plains Ecoregion of Texas

“…Findings such as these may correspond with parasite phylogenies. While much of the virulence of a parasite highly depends on the host environment (Leung and Koprivnikar, 2016) general effects may be similar in parasites that inhabit a certain area of the body, such as that of gastrointestinal parasites. However, definite conclusions cannot be made based solely on phylogenetic relationships.…”