Host dispersal as the driver of parasite genetic structure: a paradigm lost?
Résumé
Understanding traits influencing the distribution of genetic diversity has major ecological and evo-lutionary implications for host–parasite interactions. The genetic structure of parasites is expectedto conform to that of their hosts, because host dispersal is generally assumed to drive parasite dis-persal. Here, we used a meta-analysis to test this paradigm and determine whether traits relatedto host dispersal correctly predict the spatial co-distribution of host and parasite genetic variation.We compiled data from empirical work on local adaptation and host–parasite population geneticstructure from a wide range of taxonomic groups. We found that genetic differentiation was sig-nificantly lower in parasites than in hosts, suggesting that dispersal may often be higher for para-sites. A significant correlation in the pairwise genetic differentiation of hosts and parasites wasevident, but surprisingly weak. These results were largely explained by parasite reproductive mode,the proportion of free-living stages in the parasite life cycle and the geographical extent of thestudy; variables related to host dispersal were poor predictors of genetic patterns. Our results donot dispel the paradigm that parasite population genetic structure depends on host dispersal.Rather, we highlight that alternative factors are also important in driving the co-distribution ofhost and parasite genetic variation.