Southern Water Vole Arvicola Sapidus Research Articles

Heterogeneous road networks have no apparent effect on the genetic structure of small mammal populations

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.

The role of the southern water vole Arvicola sapidus in the diet of predators: a review

Abstract For the recovery and conservation of endangered species such as the southern water vole Arvicola sapidus, it is important to understand the effects of predation on their populations. The impact of a predator on a prey species depends on the dynamics and structure of their populations, the abundance of both species and their relationships with other species. When considering broad geographic areas, the analysis of the trophic dimension can provide an estimate of the effect of predatory pressure on the prey. To determine the potential impact of predators on the southern water vole, we used information provided in 74 studies concerning the diet of predators in the geographical range of the prey species. The trophic spectrum was determined based on faeces, stomach contents or pellets in which the arvicoline was present. Based on the percentage of biomass consumed in each of nine trophic categories, the potential impact posed by predators was linked with dietary profile, trophic diversity, intensity of southern water vole consumption and availability of preferred prey. In the localities studied, southern water voles are not the preferred prey of any of the predators we considered, but represent an alternative prey for some of them, especially when their main prey species are scarce. The predators with the greatest potential impact on southern water vole populations are Lutra lutra and Ardea cinerea; those with a moderate impact are some mesocarnivores (Felis silvestris, Genetta genetta, Neovison vison, Vulpes vulpes and Martes foina), a bird frequenting aquatic environments (Ciconia ciconia), and the raptors Aquila fasciatus and Hieraaetus pennatus. The results obtained may be useful in the planning of measures for the conservation of the southern water vole, such as translocations or reintroductions, and in the design of strategies to reduce predatory pressure with the aim of promoting the success of these programmes.

First documented attack of southern water vole Arvicola sapidus Miller, 1908 on a viperine snake Natrix maura (Linnaeus, 1758), on the Montsant river (NE Iberian Peninsula)

. 2002, Flechoso & Alarcos 2009), which mainly occurs in females during pregnancy and lactation, in response to a higher protein requirement (Strachan 1997). The females are territorial (Roman 2007), espe-cially in the breeding season, which is a defence me-chanism for spatial and trophic resources (Ostfeld 1990). Females defend offspring against conspecifics and other species through strategies such as moving pups to other nests when threatened. Presumably, given the references to the aggressiveness shown by some individuals of semi-aquatic species of

Revisión del estatus del topillo de Cabrera Microtus cabrerae Thomas, 1906 y la rata de agua Arvicola sapidus Miller, 1908 en las Sierras Subbéticas cordobesas (Andalucía)

We analyzed the presence of the Cabrera’s vole Microtus cabrerae at the Subbetic mountains of Córdoba (South of Spain). Although the subfossil remains proved that the vole lived at this region in the past, the absence of new founds of extant populations in its tipical habitats suggest that it has disappeared. Simultaneously, we analyzed the situation of the southern water vole Arvicola sapidus, whose populations are clearly threatened.