Ability of wildlife overpasses to provide connectivity and prevent genetic isolation.
We reviewed research on wildlife overpasses in the context of their genetic effectiveness to provide connectivity between population patches that have been isolated by road construction. The potential ecological consequences of such habitat fragmentation include reduction of gene flow between subpopulations and hence an increase in genetic differentiation and a decrease in genetic diversity. Among the solutions to provide connectivity between patches isolated by roads, wildlife overpasses are one of the most expensive alternatives. Despite the high costs associated with their construction, most of the studies assessing their use by wildlife remain observational, reporting evidence for passage use but few data on the number of individual crossings. Moreover, the use itself of wildlife overpasses does not appear sufficient to assess their effectiveness from a genetic viewpoint because a minimum number of individuals is required to assure gene flow between population patches and because the spatiotemporal dimension of individual movements and demographic parameters of subpopulations must be considered. So far, there is no evidence that wildlife overpasses do or do not efficiently address genetic issues. This lack of data is probably due to the fact that few mitigation efforts have implemented monitoring programs that incorporate sufficient experimental designs into pre- and postconstruction evaluation. To assess the genetic effectiveness of wildlife overpasses, long-term monitoring programs, including fieldwork and genetic analyses, are needed.
Corlatti
Luca
L
Department of Integrative Biology and Biodiversity Research, Institute of Wildlife Biology and Game Management, University of Natural Resources and Applied Life Sciences, Gregor-Mendel-Str. 33, A-1180 Vienna, Austria. luca.corlatti@boku.ac.at
Hackländer
Klaus
K
Frey-Roos
Fredy
F
D000063:Accidents, Traffic / Q000517:prevention & control*; D000818:Animals; D000835:Animals, Wild / Q000235:genetics*; D003247:Conservation of Natural Resources / Q000379:methods*; D017753:Ecosystem; D004779:Environment Design; D051456:Gene Flow / Q000235:genetics*; D005828:Genetics, Population