Coevolutionary arms races: increased host immune defense promotes specialization by avian fleas.
We investigated the relationship between host defense and specialization by parasites in comparative analyses of bird fleas and T-cell mediated immune response of their avian hosts, showing that fleas with few main host species exploited hosts with weak or strong immune defenses, whereas flea species that parasitized a large number of host species only exploited hosts with weak immune responses. Hosts with strong immune responses were exploited by a larger number of flea species than hosts with weak responses. A path analysis model with an effect of T-cell response on the number of host species, or a model with host coloniality directly affecting host T-cell response, which in turn affected the number of host species used by fleas, best explained the data. Therefore, parasite specialization may have evolved in response to strong host defenses.
Møller
A P
AP
Laboratoire de Parasitologie Evolutive, Université Pierre et Marie Curie, Paris Cedex 05, France. amoller@snv.jussieu.fr
Christe
P
P
Garamszegi
L Z
LZ
D000818:Animals; D005075:Biological Evolution; D001717:Birds / Q000276:immunology* / Q000469:parasitology*; D006790:Host-Parasite Interactions; D007111:Immunity, Cellular; D005423:Siphonaptera / Q000472:pathogenicity*; D013601:T-Lymphocytes / Q000276:immunology*