Recurrent evolution of host-specialized races in a globally distributed parasite

• Published in: Proceedings of the Royal Society. B, Biological sciences Vol. 272; no. 1579; pp. 2389 - 2395
• Main Authors: McCoy, K.D, Chapuis, E, Tirard, C, Boulinier, T, Michalakis, Y, Le Bohec, C, Le Maho, Y, Gauthier-Clerc, M
• Format: Journal Article
• Language: English
• Published: London The Royal Society 22.11.2005; Royal Society, The
• Subjects: Animals; Aptenodytes patagonicus; Biodiversity; Biological Evolution; Birds - parasitology; Borrelia burgdorferi; Colonial Seabirds; Ectoparasite; Eudyptes chrysocome; Eudyptes chrysolophus; Evolution; Evolution, Molecular; Fratercula; Fratercula arctica; Genetic loci; geographical variation; Hemispheres; Host-Dependent Dispersal; Host-Parasite Interactions; host-parasite relationships; Ixodes uriae; Ixodidae; Life Sciences; Marine; Microbiology and Parasitology; Parasite hosts; Parasites; Parasitology; Penguins; Population Genetic Structure; Population genetics; Population structure; Populations and Evolution; Rissa; Rissa tridactyla; Sea birds; seabirds; Species Specificity; Ticks; Ticks - classification; Ticks - genetics; Ticks - physiology; Uria; Uria aalge; Vector-Borne Disease; ectoparasite; host-dependent dispersal; Ixodes uriae; colonial seabirds; population genetic structure; vector-borne disease
• ISSN: 0962-8452; 1471-2954
• DOI: 10.1098/rspb.2005.3230

The outcome of coevolutionary interactions is predicted to vary across landscapes depending on local conditions and levels of gene flow, with some populations evolving more extreme specializations than others. Using a globally distributed parasite of colonial seabirds, the tick Ixodes uriae, we examined how host availability and geographic isolation influences this process. In particular, we sampled ticks from 30 populations of six different seabird host species, three in the Southern Hemisphere and three in the Northern Hemisphere. We show that parasite races have evolved independently on hosts of both hemispheres. Moreover, the degree of differentiation between tick races varied spatially within each region and suggests that the divergence of tick races is an ongoing process that has occurred multiple times across isolated areas. As I. uriae is vector to the bacterium responsible for Lyme disease Borrelia burgdorferi sensu lato, these results may have important consequence for the epidemiology of this disease. With the increased occurrence of novel interspecific interactions due to global change, these results also stress the importance of the combined effects of gene flow and selection for parasite diversification.