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Free keywords:
avian malaria; avian migration; disease ecology; host–parasite interaction; plasmodium; stable isotope; δ13C; δ15N
Abstract:
Parasites exert a major impact on the eco-evolutionary dynamics of their
hosts and the associated biotic environment. Migration constitutes an
effective means for long-distance invasions of vector-borne parasites and
promotes their rapid spread. Yet, ecological and spatial information on
population-specific host–parasite connectivity is essentially lacking. Here, we
address this question in a system consisting of a transcontinental migrant
species, the European barn swallow (Hirundo rustica) which serves as a
vector for avian endoparasites in the genera Plasmodium, Haemoproteus
and Leucocytozoon. Using feather stable isotope ratios as geographically informative
markers, we first assessed migratory connectivity in the host: Northern
European breeding populations predominantly overwintered in dry,
savannah-like habitats in Southern Africa, whereas Southern European
populations were associated with wetland habitats in Western Central
Africa. Wintering areas of swallows breeding in Central Europe indicated a
migratory divide with both migratory programmes occurring within the
same breeding population. Subsequent genetic screens of parasites in the
breeding populations revealed a link between the host’s migratory programme
and its parasitic repertoire: controlling for effects of local breeding
location, prevalence of Africa-transmitted Plasmodium lineages was significantly
higher in individuals overwintering in the moist habitats of Western
Central Africa, even among sympatrically breeding individuals with different
overwintering locations. For the rarer Haemoproteus parasites, prevalence
was best explained by breeding location alone, whereas no clear pattern
emerged for the least abundant parasite Leucocytozoon. These results have
implications for our understanding of spatio-temporal host–parasite dynamics
in migratory species and the spread of avian borne diseases.
