Grilo, C., del Cerro, I., Ramiro, V., Molina-Vacas, G., Fernández-Aguilar, X., Porto, F., Ascensao, F., Román, J., Fonseca, C., Godoy, J.A. y Revilla, E. Does daily movements can predict the genetic structure of small mammal populations? 2014 IENE International Conference. Programme and abstracts. Malmö: Infrastructure & Ecology Network Europe. 2014, pag. 152. ISSN 978-91-637-7327-3
Roads can constrain movements of individuals and consequently gene flow across landscape. There is a consensus among experts that some species show road surface and width avoidance behavior. However, little attention has been paid on how spatial behavior can be translated into mortality risk and population genetic structure. With this study we examine the strength of the barrier effects of different roads types (4-lane highway, 2-lane paved road and unpaved road) on three rodent species with varying life-history traits: water vole Arvicola sapidus, pine vole Microtus duodecimcostatus and algerian mouse Mus spretus. More specifically, we address 1) the influence of traffic on individual movements, 2) the effect of road type (width/pavement) on crossing rates, 3) the annual risk of mortality and 4) the genetic structure of populations on both sides of the different roads. A total of 79 voles were caught in the vicinity of roads and 6481 locations were recorded through radio tracking. We used generalized linear mixed models to evaluate the effect of traffic on individual movements, compared observed crossing rates with simulations without roads, and used the information of number of crossings per individual and the probability of being killed while crossing a road to estimate the annual mortality risk. We also obtained 200 tissue samples for pine vole and Algerian mouse and estimate the genetic differentiation (FST) among groups of samples on both sides of roads. As expected, paved roads function as artificial territorial boundaries for the three species. Traffic intensity had only negative influence on water vole movements. Crossing rates decrease as the road width increase and paved roads have a negative effect on individual’s crossings, except for pine vole that had the highest crossing rate, and the 2-lane highway show a neutral effect. The likelihood of being killed during a crossing event at high traffic highway segments for pine vole and Algerian mouse at 4-lan highways were 0.22 and 0.05, respectively. Unexpectedly, pine vole populations show genetic structure at 4-lane highways while Algerian mouse populations did not show significant genetic structure for all type of roads. Our study shows that daily movement patterns of small mammals towards roads cannot be translated on dispersal and gene flow. Further information is needed to understand the implications of mortality risk in the viability of pine vole population occurring in the vicinity of heavy traffic roads. We recommend that only complementary studies of spatial behavior, population density and genetics may explain the mechanisms underlying the barrier effect of roads on wildlife.
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