Dispersal and distribution of the tick Ixodes uriae within and among seabird host populations: The need for a population genetic approach

The aim of this study was to characterize the spatial distribution of the t ick Ixodes uriae within and among populations of its seabird hosts and to c onsider the potential insight that could be gained by a population genetic approach to the issue of dispersal of this rick, Analyses of data collected around the Avalon Peninsula, Newfoundland, indicated that both the prevale nce and mean abundance of ticks varied significantly among sample locations . Whereas ticks were found on all 4 host species examined (Rissa tridactyla , Uria aalge, Alca torda, Fratercula arctica), infestation prevalence and m ean abundance differed among the species. On R. tridactyla, ticks were sign ificantly aggregated at the among-nest scale and nestling infestation was s patially autocorrelated. Conversely, ticks were not aggregated among chicks within nests. These results enabled us to make a priori predictions regard ing tick dispersal and host specificity and suggest there may be spatial st ructure of Ixodes uriae populations at both macro- and microgeographic scal es. Investigating the population genetic structure of ticks within and amon g populations of hosts with different breeding biologies should provide dir ect insight into the metapopulation dynamics of such a spatially structured system.