Barrier effect is a road‐related impact affecting several animal populations. It can be caused by behavioural responses towards roads (surface and/or gap avoidance), associated emissions ...(traffic‐emissions avoidance) and/or circulating vehicles (vehicle avoidance). Most studies so far have described road‐effect zones along major roads, without determining the actual factor inducing the behavioural response. The purpose of the present study was to assess the factors potentially causing road‐effect zones in a heterogeneous road network (with variations in road width, road surface and traffic volume) and eventually to estimate the reduction of habitat quality imposed by roads within a protected area (Doñana Biosphere Reserve, Spain). As model species, we used two ungulates, red deer Cervus elaphus and wild boar Sus scrofa. We surveyed the presence of both species along 200‐m transects. All transects started and were perpendicular to reference roads (those with a traffic volume above 10 cars per day), often intersecting unpaved minor roads with virtually no traffic. The presence probability of both species was mainly affected by the distance to the nearest road (in most cases unpaved roads without traffic), but also by the proximity to reference roads. Red deer presence was also affected by the traffic volume of the nearest reference road. At a regional scale, the overall road network within the protected area imposes a reduction in presence probability of 40% for red deer and 55% for wild boar. A road network optimization, decommissioning unused and unpaved roads, would re‐establish almost entirely the potential habitat quality (91% for both species). Synthesis and applications. We found that both study species avoided roads regardless of their surface or traffic volume, suggesting a response due to gap avoidance which may be based on the association between linear infrastructures and the possibility of vehicles occurring along them. The overall behavioural response can substantially decrease habitat quality over large scales, including the conservation value of protected areas. For this reason, we recommend road network optimization by road decommissioning to mitigate the impact of roads at a regional scale, with potential positive effects at ecosystem level.
Temporal variability in primary productivity can change habitat quality for consumer species by affecting the energy levels available as food resources. However, it remains unclear how ...habitat-quality fluctuations may determine the dynamics of spatially structured populations, where the effects of habitat size, quality and isolation have been customarily assessed assuming static habitats. We present the first empirical evaluation on the effects of stochastic fluctuations in primary productivity—a major outcome of ecosystem functions—on the metapopulation dynamics of a primary consumer. A unique 13-year dataset from an herbivore rodent was used to test the hypothesis that inter-annual variations in primary productivity determine spatiotemporal habitat occupancy patterns and colonization and extinction processes. Inter-annual variability in productivity and in the growing season phenology significantly influenced habitat colonization patterns and occupancy dynamics. These effects lead to changes in connectivity to other potentially occupied habitat patches, which then feed back into occupancy dynamics. According to the results, the dynamics of primary productivity accounted for more than 50% of the variation in occupancy probability, depending on patch size and landscape configuration. Evidence connecting primary productivity dynamics and spatiotemporal population processes has broad implications for metapopulation persistence in fluctuating and changing environments.
Road-kill represents a major threat for butterflies and more generally for pollinators. Here we report an observation of conspicuous aggregations of butterflies mud-puddling on roadsides and, for ...this reason, being massively road-killed by farm vehicles.
Implications for insect conservation
While the reported observation by itself may not entail a significant threat to the populations of the observed species, it provides the opportunity to discuss an overlooked ecological trap, potentially affecting butterflies and especially threatened or endemic species. Indeed, this kind of mortality, due to a very common behaviour in butterflies, could affect any species in any area, and for this reason should be furtherly investigated and, when necessary, appropriately mitigated. Mitigation actions should prevent the formation of moist surfaces along roadsides, and in case of wide verges, provide artificial mud-puddling sites away from roads, in correspondence with the ecotone between roadside and matrix habitat.
Interspecific competition affects population dynamics, distributional ranges, and evolution of competing species. The competitive exclusion principle states that ecologically similar species cannot ...coexist unless they exhibit niche segregation. Herein, we assess whether niche segregation allows the coexistence of Crocidura russula and C. suaveolens in southwestern Iberia and whether segregation is the result of current (ecological effect) or past (evolutionary effect) competition. We performed an annual live-trapping cycle in the two main habitats of the Odiel Marshes Natural Reserve (OMNR), the tidal marsh and the Mediterranean forest, both in syntopic (i.e., where both species co-occur) and allotopic (where only one of the two species occurs) sites within this Reserve. We modeled the presence–absence of each species in both habitats and sites by generalized linear mixed models. The coexistence of both species was favored by spatial and temporal niche segregation. Crocidura suaveolens was restricted to tidal marsh and did not occupy Mediterranean forest, even when C. russula was absent. We interpret this to be the result of competition in the past triggering an evolutionary response in C. suaveolens towards its specialization in tidal marsh. Moreover, the specialist C. suaveolens currently is outcompeting C. russula in tidal marshes, reversing the dominance pattern observed elsewhere. The degree of co-occurrence between both species in syntopic sites was low, as they showed inverse dynamics of seasonal abundances. Interspecific competition leading to habitat specialization favors the coexistence of these ecologically similar species.
At the beginning of the 20th century
was described based on one specimen from Basque Provinces, North of Spain. Later, some authors considered it a junior synonym of
, without any data to support ...this statement, so the eight existing specimens were registered as records of that species. Our objective was to clarify the taxonomic status of
. Since DNA could not be obtained from the existing specimens and the coloration was originally poorly described, an attempt was made to make an assignment based on the original biometric data of two individuals, the only ones identified by Cabrera for which there is biometric information: the holotype and a specimen from Colindres, Cantabria. The body measurements were surely altered by conservation techniques, rendering any identification uncertain, whereas the skull biometry assigns the specimens to
. We propose that
should be treated as junior synonym of
The use of wildlife road-crossing structures (WCS hereafter) is less monitored for small mammals than for more emblematic species. Furthermore, because of the undeniable difficulty of small-mammal ...track identification, most biologists usually carry out general surveys without species recognition. We hypothesized that general surveys traditionally used for monitoring WRC by small mammals may be biased because the degraded habitats along roads are mainly used by generalist and not specialist species. For this reason, we compared the results of a general small-mammal survey with those from a species-specific one, focusing on 3 study species: 1 habitat generalist (North American deer mouse Peromyscus maniculatus), 1 forest specialist (southern red-backed vole Myodes gapperi), and 1 prairie specialist (meadow vole Microtus pennsylvanicus). We sampled along 4 types of WCS (overpasses, open-span underpasses, and both elliptical and box culverts) in Banff National Park (Canada), by placing footprint track tubes along the WCS, and as a reference in front of their entrances (mainly located in roadside grasslands) and in the surrounding woodlands. Using the traditional general survey, we did not detect significant differences in small-mammal presence among WCS and reference sites. In contrast, species-specific surveys showed that only the deer mouse (a generalist species) consistently used the WCS. The deer mice did not show preferences for any WCS type, whereas the specialist species (voles) used only overpasses. Therefore, general surveys used without species identification can underestimate the value of WCS for specialist small mammals, with relevant conservation implications. As a consequence, we recommend species-specific surveys of WCS suitability for small mammals. We also suggest improving the habitat (or at least the cover availability) in the WCS and along the space between them and the surrounding environments to increase WCS suitability for specialist species.
Abstract
Despite their potential importance, biological processes such as competitive exclusion (CE) have been largely neglected in phylogeographical studies. Here, we analyse the role of glacial ...events and CE in the evolutionary history of the lesser white-toothed shrew, Crocidura suaveolens, in Iberia based on cytochrome b sequences. All the Iberian samples grouped together with the rest of western European populations within the previously described clade IV. We identified three distinct evolutionary lineages within this major clade, two of them occurring exclusively in Iberia. Iberian lineage B extends throughout the northwest with a continuous distribution and moderate to high diversity values, whereas Iberian lineage C has a highly patchy distribution and is structured in four sublineages, all having low diversity values. No signs of demographic growth were detected for any of the lineages. The evolutionary history of C. suaveolens in Iberia supports the refugia-within-refugia scenario, but ecological studies in areas of sympatry, molecular and fossil datings, and contrasting patterns in the Italian Peninsula suggest that CE exerted by C. russula since its arrival in Iberia has been the main factor shaping the distribution, phylogeography and population genetics of lineage C.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
The near threatened Phengaris nausithous is distributed in two large mountainous areas in the northern part of the Iberian Peninsula, living in small dispersed populations. During July and August of ...2012–2015 we systematically searched for the species in the southeastern part of the Cordillera Cantábrica. We found 38 new populations grouped into seven metapopulations. Two of the latter are the largest known, representing 34 % of the species’ occurrence range in Spain. The discovery of these new metapopulations does not improve the conservation status of P. nausithous in the SW of Europe because a land consolidation project currently underway and an established peat extraction plant could lead to the imminent extinction of the largest metapopulations. However, there is still time to reverse the present course of change. Knowledge of these recently discovered populations allows the establishment of management measures to protect them over the long term.
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