Population connectivity across a highway in large ungulates: testing the power of redundancy analyses

Preserving nature in an urbanized modern environment proves to be rather difficult. A lot of effort is put into conserving the natural habitat. However in western Europe this natural habitat is reduced to small patches if not completely gone. Centuries of urbanization have reformed the landscape from a wild, natural environment to a more controlled, humanized creation. This shaping of the scenery has lead to a massive increase of human-induced pressure on natural populations of organisms. Large natural areas have been transformed into cities and villages in order to accommodate for the growing size of the human population. These hotspots for human activity were surrounded by vast areas of food crops and feeding grounds for domesticated animals. To be able to interact with each other and exchange goods, extensive transport networks were created. This all lead to an excessive devastation of the former natural habitat. In recent years efforts have been done to reduce the impact of human life on its environment. Nature reserves have been established and attempts have been made to reconnect fragmented habitats. However quantifying the magnitude of the impact of the transport infrastructure on animal populations, has not fully been done yet. In order to optimize nature preservation measures, a thorough understanding of the impact on the ecosystem is essential. Based on research done in 2012 on the effect of the E411 motorway in Wallonia as a barrier for gene flow in red deer (Cervus elaphus) and wild boar (Sus scrofa) populations, additional statistical analyses were performed. Using distance based redundancy analyses, a method that proved to be more accurate than the Bayesian cluster methods used in 2012, it was determined the motorway accounted for 1.7% of the total genetic structure in the red deer population. This means gene flow for red deer across the motorway is almost inexistent. The wild boar population did not show any significant impact of the motorway. This provides useful information to conservation policy makers, as the fenced motorway does not seem to have quite the same impact on different species of large ungulates. In determining which type of corridor is needed to connect fragmented patches of nature, it is essential not only to take into account which species can use it, but also which species are in need of said corridor.