The influence of local, landscape and spatial factors on the distribution of the Lusitanian and the Mediterranean pine voles in a Mediterranean landscape

Abstract

a b s t r a c tThis study evaluated the relative contributions of local and landscape factors, and of spatial structure on the regional distribution of both the Lusitanian (Microtus lusitanicus Gerbe, 1879) and Mediterranean pine voles (Microtus duodecimcostatus de Selys-Longchamps, 1839) over an area of 1613 km 2 within a Mediterranean landscape in central Portugal.Three sets of explanatory variables (20 local, 23 landscape, and 6 spatial) were analysed independently by means of a generalized linear model, followed by a variance partitioning procedure.Variance in the distribution patterns of M. lusitanicus and M. duodecimcostatus largely was explained by fine-scale environmental factors but spatial effects also were important, especially for the distribution of M. duodecimcostatus. The close proximity of verges and the high abundance of humidity and coarse sand in the soil were the most influencing local-scale factors for the presence of M. lusitanicus; meanwhile on a larger scale, the high abundance of linear habitats was the main landscape feature determining its occurrence. Regarding the presence of M. duodecimcostatus, the close proximity of verges, high tree canopy cover and herbaceous vegetation biomass were the most influential local explanatory variables for its occurrence, while the absence of shrubs in the surrounding habitat was the main factor regulating species presence at a landscape scale. Similarities identified between the two species primarily were related to descriptors of cover, food and burrows, while differences were related to opposing spatial trends and coarse-scale descriptors.

Local coexistence and niche differences between the Lusitanian and Mediterranean pine voles (Microtus lusitanicus and M. duodecimcostatus)

“…This higher importance of local factors was also obtained in a previous research for the presence/absence patterns of each species (Santos et al 2010b).…”

“…As the range of this species includes major areas of temperate bioclimates (Rivas-Martı´nez et al 2002), it is expected that, at finer scales, it prefers fresher and more humid sites, which tend to occur more frequently at higher altitudes within a Mediterranean environment. Indeed, previous results indicated that in this study area the presence of M. lusitanicus was positively associated with more humid soils (Santos et al 2010b). These differences in niche patterns could also be related to the physiological traits of the two species as a response to environmental variability.…”

“…Previous results indicated that the two species have low abundance in the region and occurrence sites are localized and spatially discontinuous (Santos et al 2010b). These characteristics and the average dispersal distances of 100-160 m for some Microtus species (M. pennsylvanicus and M. arvalis; McShea and Madison 1992) may create conditions that shorten the possibilities for local co-occurrence to become common and widespread in the region.…”

“…Specifically for this area, there is no detailed information that reports or quantifies the coexistence of the two species at finer scales. Both species occupy preferentially open habitats, natural and agricultural (Cotilla and Palomo 2007;Mira and Mathias 2007), in close association with verges (Santos et al 2010b), and both species feed on roots, tubers, fruits and other parts of plants (Vinhas 1993;Cotilla and Palomo 2007;Mira and Mathias 2007). In this sense, it would be valuable to detail and quantify coexistence patterns of these voles in the predicted sympatry area, and obtain more information on niche differences among them.…”

p53 gene discriminates two ecologically divergent sister species of pine voles

“…The largely allopatric distribution range of these two species may well reflect this ecological divergence. In sympatry, both the voles occupy a specialized ecological niche, in which soil characteristics seem to be particularly relevant (Borghi et al, 1994;Santos et al, 2009a, b;Santos et al, 2010;Santos et al, 2011). Niche specialization may involve distinctive physiological and genetic adaptations (Singh et al, 2009;Hadid et al, 2013), probably species and stress environmental specific, as suggested with the S104E variation observed within the P53 protein of high-altitude M. oeconomus or the R174K mutation in P53 of the subterranean Spalax (Ashur-Fabian et al, 2004;Zhao et al, 2013).…”