Genetic variation and prevalence of blood parasites do not correlate among bird species

Abstract

Models of host±parasite co-evolution suggest that parasites can exert frequency-dependent selection on their hosts, favouring rare alleles that confer resistance against widespread parasites and thus contributing to the maintenance of genetic variation, at some loci at least. If parasites are important in maintaining variation at many loci, then host species incurring a high prevalence of parasite infections should exhibit greater levels of genetic variation than host species incurring a lower prevalence. Using data from electrophoretic studies and from ®eld surveys of haematozoan infections, we constructed a dataset including 103 species of North American and European birds to test this prediction. After controlling for sampling effort and phylogenetic in¯uences, we found no relationship between parasite prevalence and either heterozygosity or polymorphism. These results do not support a role for parasites in the overall maintenance of genetic variation via frequency-dependent selection.

Links between blood parasites, blood chemistry, and the survival of nestling American crows

“…The strength of selection pressure that parasites place on their hosts will depend on the extent to which they cause disease in those hosts. Studies that broadly use the avian hematozoa as a model system to address important evolutionary questions about host–pathogen interactions (Atkinson & Van Riper, ; Hamilton & Zuk, ; Poulin et al., ; Zuk & Borrello, ) make the underlying assumption that hemosporidian infections cause disease (i.e., that the organisms are pathogenic). Although hemosporidian infections do, indeed, appear costly in some hosts and contexts (Asghar et al., ; Atkinson & Van Riper, ; Krams et al., ; Sol et al., ), many studies have failed to detect negative consequences of infection, particularly among chronically infected adults (Cornelius et al., ; Fargallo & Merino, ; Piersma & van der Velde, ; Podmokla et al., ; Zylberberg et al., ).…”

“…Theoretical and empirical data indicate that parasites may promote the evolution and maintenance of genetic diversity (Anderson & May, ), favor the evolution of sexually selected traits (Hamilton & Zuk, ), and drive host population cycles (Hudson, Dobson, & Newborn, ). The avian hemosporidian parasites in the genera Leucocytozoon , Plasmodium , and Hemoproteus have been used as a model system in the study of such host–parasite interactions (Atkinson & Van Riper, ; Hamilton & Zuk, ; Poulin, Marshall, & Spencer, ; Zuk & Borrello, ), yet their documented costs—and, potentially, the magnitude of selection pressure that they exert—appear to vary widely among hosts, populations, and contexts. They can have devastating impacts in naïve populations (Atkinson & Samuel, ), and many studies have reported negative associations with infection in endemic areas, including reductions in condition (Marzal, Bensch, Reviriego, Balbontin, & de Lope, ; Merino, Moreno, Sanz, & Arriero, ), antipredator behavior (Garcia‐Longoria, Moller, Balbontin, de Lope, & Marzal, ; Mukhin et al., ), mating display behavior (Bosholn, Fecchio, Silveira, Braga, & Anciaes, ), survival (Asghar et al., ; Krams et al., ; Sol, Jovani, & Torres, ), and reproductive output (Asghar, Hasselquist, & Bensch, ; Knowles, Palinauskas, & Sheldon, ; Marzal et al., ; Merino et al., ).…”

Parasite mediated mortality and host immune response explain age-related differences in blood parasitism in birds

“…Thus, for some time, researchers have faced the paradox of using Haemoproteus as a model to address important ecological and evolutionary questions (e.g. Hamilton and Zuk 1982;Poulin et al 2000), while having no compelling evidence that it causes a detrimental impact on wild animals.…”

Consequences of chronic infections with three different avian malaria lineages on reproductive performance of Lesser Kestrels (Falco naumanni)

“…Infectious diseases have a major influence on host population dynamics and evolution, promoting host genetic variation and influencing co-evolutionary processes (Hamilton and Zuk 1982;Poulin et al 2000). The study of the interaction between avian malaria parasites and their hosts has greatly contributed to the understanding of several aspects of host/parasite ecology and evolution (Hamilton and Zuk 1982;Poulin et al 2000;Bensch et al 2000).…”

“…The study of the interaction between avian malaria parasites and their hosts has greatly contributed to the understanding of several aspects of host/parasite ecology and evolution (Hamilton and Zuk 1982;Poulin et al 2000;Bensch et al 2000). Further, avian malaria parasites are responsible for widespread declines in Hawaiian native forest birds (van Riper et al 1986), and several negative effects, such as increased mortality and reduced reproductive outputs, have been described in a number of bird species (Atkinson et al 2000; Dawson and Bortolotti 2000;Merino et al 2000;Sol et al 2003).…”