Iversen, Lars Lønsmann3; Rannap, Riinu3; Thomsen, Philip Francis4; Kielgast, Jos5; Jensen, Kaj Sand5
1 Natural History Museum of Denmark, Natural History Museum of Denmark, Faculty of Science, Københavns Universitet2 Freshwater Biology, Department of Biology, Faculty of Science, Københavns Universitet3 Biologisk Institut, Københavns Universitet4 Natural History Museum of Denmark, Natural History Museum of Denmark, Faculty of Science, Københavns Universitet5 Freshwater Biology, Department of Biology, Faculty of Science, Københavns Universitet
Species’ dispersal abilities have been considered a major driving force in establishment and maintenance of large range sizes. However, recent studies question the general validity of this relationship because the relationship between dispersal ability and range size might in some cases be less important than species phylogeny or local spatial attributes. In this study we used the water beetle Graphoderus bilineatus a philopatric species of conservation concern in Europe as a model to explain large range size and to support effective conservation measures for such species that also have limited dispersal. We recorded the presence/absence of G. bilineatus and measured 14 habitat and 20 landscape variables at 228 localities in Estonia, Poland and Sweden within the core range of the species. Using information theory and average multivariate logistic regression models we determined that presence of G. bilineatus depended on landscape connectivity, distance to a possible source habitat, and stability of the site; however, specificity of habitat characteristics was not vital for the species. We reason that the large range of G. bilineatus is best explained by the historical combination of lakes, river systems and wetlands which used to be highly connected throughout the central plains of Europe. Our data suggest that a broad habitat niche can prevent landscape elements from becoming barriers for species like G. bilineatus. Therefore, we question the usefulness of site protection as conservation measures for G. bilineatus and similar philopatric species. Instead, conservation actions should be focused at the landscape level to ensure a long-term viability of such species across their range.