Abstract
BackgroundParasite prevalence and diversity are determined by the distribution of hosts and vectors and by the interplay among a suite of environmental factors. Distributions of parasite lineages vary based on host susceptibility and geographical barriers. Hemoparasites of the genera Haemoproteus and Plasmodium have wide distributions, and high prevalence and genetic diversity within perching birds (Order Passeriformes). The rufous-collared sparrow (Zonotrichia capensis) is widely distributed in Central and South America across an immense diversity of environments from sea level to more than 4000 meters above sea level. It therefore provides an excellent model to investigate whether altitudinal and latitudinal gradients influence the distribution, prevalence and diversity of haemosporidian parasites, their population structure and the biogeographical boundaries of distinct parasite lineages.ResultsWe assembled samples from 1317 rufous-collared sparrows spanning 75 locales from across Central and South America (between 9.5°N and 54°S; 10–4655 meters above sea level). We used DNA sequence data from a fragment of the mitochondrial cytochrome b gene (cytb) of Haemoproteus and Plasmodium from 325 positive samples and found prevalences of 22 and 3%, respectively. Haemoproteus exhibited a higher prevalence than Plasmodium but with comparatively lower genetic diversity. We detected a relationship of Plasmodium and Haemoproteus prevalence with altitude and latitude; however, altitude and latitude did not influence parasite diversity.ConclusionsParasite lineages showed a phylogeographical boundary coincident with the Andes Mountains, although we also observed a north-south disjunction in Peru for Haemoproteus. Haemosporidian distribution was not homogeneous but differed based on latitude and altitude. This is most probably due to environmental factors that have influenced both vector distribution and abundance, as well as parasite development. Our study provides key insights on the distribution of haemoparasite lineages and parasite dynamics within hosts.
Highlights
Parasite prevalence and diversity are determined by the distribution of hosts and vectors and by the interplay among a suite of environmental factors
Haemoproteus exhibits greater lineage diversity than Plasmodium; this pattern differs in South America, where a higher avian host diversity coupled with low Plasmodium-host specificity leads to greater lineage diversity of Plasmodium than Haemoproteus [15]
Considering all of the data, the lowest prevalence was evident in Colombia for both Haemoproteus and Plasmodium, while in Peru, Argentina and Chile a higher prevalence was detected for Haemoproteus relative to Plasmodium
Summary
Parasite prevalence and diversity are determined by the distribution of hosts and vectors and by the interplay among a suite of environmental factors. Biogeographical patterns for distribution, prevalence and diversity of haemosporidian parasites have been described for multiple regions worldwide Prevalences for both genera (Haemoproteus and Plasmodium) have been shown to be lower at higher altitudes [8, 9], with a greater limitation of Plasmodium at higher altitudes [10, 11]. In a meta-analysis, Clark [16] found no correlation between parasite diversity and latitude worldwide; this study did not include considerations of avian host species in their analyses This is a crucial factor since haemosporidia lineage diversity should relate to the density of susceptible avian hosts and to parasite-host specificity [17, 18]. Several lineages of Plasmodium show extreme generalist host-parasitism strategies, while others appear to be restricted to particular host families over recent evolutionary history [4]
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