title: Heterogeneous road networks have no apparent effect on the genetic structure of small mammal populations.
abstract: Roads are widely recognized to represent a barrier to individual movements and, conversely, verges can act as potential corridors for the dispersal of many small mammals. Both barrier and corridor effects should generate a clear spatial pattern in genetic structure. Nevertheless, the effect of roads on the genetic structure of small mammal populations still remains unclear. In this study, we examine the barrier effect that different road types (4-lane highway, 2-lane roads and single-lane unpaved roads) may have on the population genetic structure of three species differing in relevant life history traits: southern water vole Arvicola sapidus, the Mediterranean pine vole Microtus duodecimcostatus and the Algerian mouse Mus spretus. We also examine the corridor effect of highway verges on the Mediterranean pine vole and the Algerian mouse. We analysed the population structure through pairwise estimates of FST among subpopulations bisected by roads, identified genetic clusters through Bayesian assignment approaches, and used simple and partial Mantel tests to evaluate the relative barrier or corridor effect of roads. No strong evidences were found for an effect of roads on population structure of these three species. The barrier effect of roads seems to be site-specific and no corridor effect of verges was found for the pine vole and Algerian mouse populations. The lack of consistent results among species and for each road type lead us to believe that the ability of individual dispersers to use those crossing structures or the habitat quality in the highway verges may have a relatively higher influence on gene flow among populations than the presence of crossing structures per se. Further research should include microhabitat analysis and the estimates of species abundance to understand the mechanisms that underlie the genetic structure observed at some sites.
authors.affiliation: Departamento de Biología de la Conservación, Estación Biológica de Doñana (EBD-CSIC), Calle Américo Vespucio s/n, E-41092 Sevilla, Spain; Centro Brasileiro de Estudos em Ecologia de Estradas/Setor Ecologia, Departamento de Biologia, Universidade Federal de Lavras, Campus Universitário, 37200-000 Lavras, Minas Gerais, Brazil. Electronic address: clarabentesgrilo@gmail.com.
authors.forename: Clara
authors.initials: C
authors.lastname: Grilo
authors.affiliation: Department of Biology & CESAM, University of Aveiro, Campus de Santiago, Aveiro, Portugal. Electronic address: ire.delcerro@gmail.com.
authors.forename: Irene
authors.initials: I
authors.lastname: Del Cerro
authors.affiliation: Department of Molecular Biology and Biochemical Engineering, University Pablo de Olavide, Sevilla, Spain. Electronic address: acenteno@upo.es.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Centeno-Cuadros
authors.affiliation: Universidade de Lisboa, Fundação da Faculdade de Ciências, C2 5º 1749-016 Lisboa, Portugal. Electronic address: vic.ramiro@hotmail.com.
authors.forename: Victor
authors.initials: V
authors.lastname: Ramiro
authors.affiliation: Departamento de Biología de la Conservación, Estación Biológica de Doñana (EBD-CSIC), Calle Américo Vespucio s/n, E-41092 Sevilla, Spain. Electronic address: jroman@ebd.csic.es.
authors.forename: Jacinto
authors.initials: J
authors.lastname: Román
authors.affiliation: Universidade de Lisboa, Fundação da Faculdade de Ciências, C2 5º 1749-016 Lisboa, Portugal. Electronic address: guillemolinavacas@gmail.com.
authors.forename: Guillem
authors.initials: G
authors.lastname: Molina-Vacas
authors.affiliation: Universidade de Lisboa, Fundação da Faculdade de Ciências, C2 5º 1749-016 Lisboa, Portugal. Electronic address: xfdezaguilar@gmail.com.
authors.forename: Xavier
authors.initials: X
authors.lastname: Fernández-Aguilar
authors.affiliation: Universidade de Lisboa, Fundação da Faculdade de Ciências, C2 5º 1749-016 Lisboa, Portugal. Electronic address: juanrodruiz@gmail.com.
authors.forename: Juan
authors.initials: J
authors.lastname: Rodríguez
authors.affiliation: Universidade de Lisboa, Fundação da Faculdade de Ciências, C2 5º 1749-016 Lisboa, Portugal. Electronic address: flavia_peter@yahoo.com.br.
authors.forename: Flávia
authors.initials: F
authors.lastname: Porto-Peter
authors.affiliation: Department of Biology & CESAM, University of Aveiro, Campus de Santiago, Aveiro, Portugal. Electronic address: cfonseca@ua.pt.
authors.forename: Carlos
authors.initials: C
authors.lastname: Fonseca
authors.affiliation: Departamento de Biología de la Conservación, Estación Biológica de Doñana (EBD-CSIC), Calle Américo Vespucio s/n, E-41092 Sevilla, Spain. Electronic address: revilla@ebd.csic.es.
authors.forename: Eloy
authors.initials: E
authors.lastname: Revilla
authors.affiliation: Departamento de Biología de la Conservación, Estación Biológica de Doñana (EBD-CSIC), Calle Américo Vespucio s/n, E-41092 Sevilla, Spain. Electronic address: godoy@ebd.csic.es.
authors.forename: José A
authors.initials: JA
authors.lastname: Godoy
mesh_terms: D063147:Animal Distribution; D000818:Animals; D000835:Animals, Wild / Q000235:genetics; D003411:Arvicolinae / Q000235:genetics*; D001499:Bayes Theorem; D017753:Ecosystem; D014644:Genetic Variation; D051379:Mice / Q000235:genetics*; D013030:Spain; D013045:Species Specificity; D014186:Transportation / Q000379:methods*
keywords: Barrier effect; Corridor effect; Gene flow; Highways