Inter-oceanic variation in patterns of host-associated divergence in a seabird ectoparasite

• Published in: Journal of Biogeography
• Main Authors: Dietrich, Muriel, Kempf, Florent, Gómez-Díaz, Elena, Kitaysky, Alexander S., Hipfner, J. Mark, Boulinier, Thierry, McCoy, Karen D.
• Other Authors: Institut Polaire Français, Centre National de la Recherche Scientifique (France), Agence Nationale de la Recherche (France), Ministére de l'Education Nationale de la Recherche et de la Technologie (France), European Commission, Consejo Superior de Investigaciones Científicas (España)
• Format: Article in Journal/Newspaper
• Language: English
• Published: Blackwell Publishing 2012
• Subjects: Co-evolution; Host race; Ixodes uriae; Microsatellites; North Atlantic; Tick; Pacific
• Online Access: http://hdl.handle.net/10261/42633; https://doi.org/10.1111/j.1365-2699.2011.02620.x; https://doi.org/10.13039/501100004794; https://doi.org/10.13039/501100001665; https://doi.org/10.13039/501100000780; https://doi.org/10.13039/501100003339

[Aim] Parasites with global distributions and wide host spectra provide excellent models for exploring the factors that drive parasite diversification. Here, we tested the relative force of host and geography in shaping population structure of a widely distributed and common ectoparasite of colonial seabirds, the tick Ixodes uriae. [Location] Two natural geographic replicates of the system: numerous seabird colonies of the North Pacific and North Atlantic Ocean basins. [Methods] Using eight microsatellite markers and tick samples from a suite of multi-specific seabird colonies, we examined tick population structure in the North Pacific and compare patterns of diversity and structure to those in the Atlantic basin. Analyses included population genetic estimations of diversity and population differentiation, exploratory multivariate analyses, and Bayesian clustering approaches. These different analyses explicitly took into account both the geographic distance among colonies and host use by the tick. [Results] Overall, little geographic structure was observed among Pacific tick populations. However, host-related genetic differentiation was evident, but was variable among host types and lower than in the North Atlantic. [Main conclusions] Tick population structure is concordant with the genetic structure observed in seabird host species within each ocean basin, where seabird populations tend to be less structured in the North Pacific than in the North Atlantic. Reduced tick genetic structure in the North Pacific suggests that host movement among colonies, and thus tick dispersal, is higher in this region. In addition to information on parasite diversity and gene flow, our findings raise interesting questions about the subtle ways that host behaviour, distribution and phylogeographic history shape the genetics of associated parasites across geographic landscapes. Financial support was provided by the French Polar Institute (IPEV, programme no. 333), the Centre National de la Recherche Scientifique ...