Mammalian Biology最新文献

Abstract

Mus cypriacus is one of three small palaeoendemic mammals that have survived the Mediterranean islands’ anthropization. This species, endemic to Cyprus, was described in 2006 and stands out as one of the last mammal species to have been discovered in Europe. Despite scarce data on its genetics, ecology, and life-history traits, Mus cypriacus is assessed as Least Concern LC in the IUCN Red List, partly due to its morphological similarity with the sympatric house mouse that prevented earlier identification. Our study uses mitochondrial and microsatellite markers to investigate this small rodent's population genetic structure and diversity. Our analysis did not identify any population genetic structure and suggested a high genetic diversity across Cyprus. When inferring habitat preference using sample locations, it appeared that M. cypriacus utilizes a diverse variety of habitats, covering more than 80% of the island. Although these results are encouraging for the conservation status of the species, they still need to be cautiously applied as potential threats may arise due to increasing habitat destruction and changes in land use. Consequently, our encouraging results should be applied judiciously. Additional ecological data are urgently needed to gain a more comprehensive understanding of this inconspicuous endemic species.

Determining the factors influencing reproductive rates is important for modeling and managing wildlife populations. In ungulates, these vital rates are often related to intrinsic characteristics such as age and body condition. We studied mid-winter pregnancy and early reproductive outcomes (offspring viability) in a reintroduced elk (Cervus canadensis) population in southeastern Kentucky, USA, modeling these rates as a function of age, body condition score, and body mass with generalized linear mixed-effects models (GLMMs) fit within an information-theoretic framework to determine which factors best predicted reproductive potential. Our models for pregnancy status suggested that pregnancy was strongly correlated with body mass and weakly with age and body condition, while models for offspring viability suggested that none of the covariates measured were predictive of parturition and offspring viability. While body mass appeared to be the strongest correlate of reproductive potential in this population, other physiological and nutritional variables likely play a role in pregnancy or fetal survival, and future work should aim to understand how these parameters both influence reproduction and are influenced by habitat management.

Large-bodied mole rats (Spalax) are a speciosus genus among obligate subterranean rodents, with seven currently recognized species, ranging from the Carpathians to the North Caucasus and further into the Caspian basin. Several conflicting hypotheses were proposed to explain the phylogenetic relationship among these taxa, mostly based on the subjective interpretation of the importance of certain morphologic characters in species delineation. We sequenced one mitochondrial (cytb) and one nuclear (IRBP) gene in six Spalax species, representing the most complete molecular dataset up to date. Both resulting phylogenies placed S. graecus, S. antiquus and S. giganteus at the base of the tree, while S. microphtalmus, S. zemni and S. arenarius appeared to have differentiated later in the evolutionary history of the genus. Cytb phylogeny supports monophyletic positions of all currently recognized species. According to the nuclear IRBP gene S. zemni and S. arenarius share similar haplotypes, which may represent either hybridization or recent separation from a common gene pool. The westernmost species S. antiquus and S. graecus represent the earliest split within the genus Spalax, indicating the possible origin of large-bodied blind mole rats from the South-West Europe. S. giganteus may represent the eastern relic of the ancient Spalax population. The central part of the genus distribution is inhabited by the most derived species: S. zemni + S. arenarius + S. microphthalmus. Large rivers of the Eastern Europe might have played a limited role in the distribution and speciation of mole rats and were crossed regularly by various genotypes.

In Germany, wolves live in a human-dominated landscape. The return of the wolf to Germany more than 20 years ago is a prime example of successful nature conservation; however, it has also led to conflict due to the high degree of landscape fragmentation and the feeding habits of the wolf. Here, the wolf diet composition was studied based on an analysis of 11,225 scats. Wolves in Germany mainly feed on wild ungulates, which comprise more than 94% of their diet. The predominant species are roe deer and wild boar, whereby in most territories roe deer dominate the diet composition. Depending on availability, red deer and fallow deer may also make up a high proportion of the diet. Seasonal and territorial variation in diet composition has been noted even in directly neighboring territories. Wolves preferentially hunt juveniles of the main prey species. With the exception of the mouflon, which has all but disappeared locally, no other ungulate species has vanished from the wolf’s diet. This study provides an overview of the varied diet of wolves in Germany since recolonization more than 20 years ago.

Roads threaten the conservation of many wildlife species. Carnivores are one of the most susceptible groups due to their habitat requirements. We explored the roadkill patterns of European polecats (Mustela putorious) on motorways and roads to investigate if these patterns depend on road type, a research topic frequently neglected in the literature. We studied 85 roadkills on motorways and 73 on roads, and the corresponding number of random points with no roadkills in every road type. We characterized them with 7 habitat and 7 road-related variables. Roadkill sites were significantly associated with the abundance of rabbit burrows. However, this effect was stronger on motorways, as they provide more suitable habitat for the establishment of prey species on their wider rights-of-way, or on the road interchange islands, which provide wide unused spaces. In contrast, road interchange islands on conventional roads that are simple intersections and have narrower rights-of-way. Furthermore, roadkills occurred in areas with lower agricultural cover. Thus, natural habitats on roadsides could act as alternative foraging areas for this carnivore increasing their roadkill risk. Our results showed the need to consider the characteristics such as the availability of prey or the surrounding habitat, as well as intrinsic characteristics of the road type when studying wildlife roadkills as the road-type-mediated patterns demand-specific mitigation measures.

Abstract

Prey species develop anti-predatory strategies as a response to minimising the risk of being predated. However, how the European rabbit (Oryctolagus cuniculus) adapts to different predator pressure is not fully known. Here, we studied the adaptive anti-predatory responses of European rabbits exposed to different terrestrial predation pressure. To do this, we took advantage of a rabbit translocation programme in the Sierra Norte Natural Park of Sevilla (SW Spain), where rabbits from the same donor population were translocated in plots with and without terrestrial predator exclusion fences (aerial predation was not excluded in any of the plots). This presented an ideal opportunity to observe whether the behaviour of individuals from the same population adapts to situations with different predator pressure; thus, their behaviour was evaluated through direct observations. Although most rabbits were observed close to cover, differences in distance to cover, group size and behaviour were observed between fenced and unfenced plots. Overall, both adult and juvenile rabbits moved further from cover in the unfenced plot than in the fenced plot. Most of the observations in the unfenced plot corresponded to rabbits in pairs or alone; whereas in the fenced plot, rabbits were primarily in pairs or in larger groups. Our findings suggest that in the unfenced plot, rabbits that moved further from cover were often part of larger groups (≥ 4 rabbits); whereas in the fenced plot, it was rabbits in smaller groups (< 4 rabbits). Rabbits in the unfenced plot were alert and running more frequently than rabbits in the fenced one; in the latter, these rabbits were mostly feeding. Other relaxed behaviours such us grooming or resting were more frequent close to cover. In summary, our results highlight rabbits' capacity to promptly adjust behaviour in response to predation risk, exhibiting adaptive anti-predatory responses tailored to different predation pressures. These insights contribute to understanding the nuanced dynamics of prey species' responses to diverse predation scenarios.

Abstract

Identifying individual animals, especially in large mammals, is an important goal for wildlife biologists and managers. Bears, occupying diverse habitats, face and experience significant conflict. Among Asian bears, the sloth bear Melursus ursinus (Shaw, 1791; Vulnerable IUCN Red List) is reported vulnerable due to negative interactions with humans, requiring solutions like identifying bear individuals using morphological features. To do so, we used an image-comparison algorithm to evaluate the uniqueness of chest markings using structural similarity index (SSIM) and trained a deep learning model based on the EfficientNet architecture for predicting an individual bear classification. We collected 1567 images (of 144 bears) to examine individual-level differences in chestmark patterns. The comparison yielded 98% accuracy in differentiating chestmarks as a unique pattern for an individual. Subsequently, we trained a circular classification model based on EfficientNet framework using augmented 5628 images for training (80%; of 115 bears), which was validated over 95% for top one and 99% for five individual predictions on 1407 testing images (20%; of 115 bears). The final step involved passing 58 non-augmented images (of 29 out-of-train bears), and the top five predictions of closely similar patterns suggested by the model were then manually compared for similarities in shapes, which suggested whether the image belonged to a new individual. The high accuracy of comparison and classification models suggests the potential applicability of this technique for helping maintain the ex-situ bear database, identifying the conflict individual and estimating bear populations.

With a global population estimated at 2000 individuals between Argentina and Chile, less than 1% of its historical population, the huemul (Hippocamelus bisulcus) is categorized as “Endangered”. Through a population viability analysis, we sought to estimate the viability of two huemul populations under different threat scenarios. Through a sensitivity analysis, we expected to identify those threats, and environmental or population variables that are more relevant for each population survival. Our main goal is to contribute to the management of the species in Chile through threats prioritization seeking to focus future conservation strategies. This research involved huemul populations from the Nevados de Chillán-Laguna del Laja Biological Corridor Biosphere Reserve (NCLL) and the Cerro Castillo National Park (PNCC). The NCLL population showed a very low probability of survival with a mean time to extinction of 45.9 years; in contrast, PNCC population exhibited a higher probability of survival with a mean time to extinction of 68.6 years. Predation and harassment by dogs seem to have the most significant negative impact on both populations’ fate. Additionally, populations were highly sensitive to the percentage of reproductive females and female mortality. Based on our findings, we proposed concentrating conservation efforts on reducing or eliminating dogs’ chances to attacks and predate huemul, as well as to focus surveillance actions on females.

Abstract

Hybridization between native and introduced species is one of the most important reasons underlying the impact on biodiversity exerted by biological invasions and also one of the hardest to be detected. The East-Asian sika deer Cervus nippon has been introduced to several European countries, where it is known to generate fertile offspring with the congeneric native red deer C. elaphus, threatening its local populations with genetic pollution. Most studies on hybrid populations have been carried out in northern and eastern Europe, whereas introductions of this deer and their effects are still poorly known in Southern countries. In this study, we updated the distribution of sika deer in Italy, where the species has been present since at least 25 years ago, but where no formal assessment has ever been conducted. We confirm the occurrence of sika deer genes in formerly pure red-deer populations in central Italy by means of genetic analyses. Further range expansion of invasive sika deer and red × sika deer hybrids is likely to lead to further hybridisations and introgression, with implications for the genetic integrity of native red deer populations.

Here we report the first thorough genetic characterization of the long-understudied red deer population of Belarus in regards to its ancestry according to mtDNA sequence analysis. Employing a 346 base pair segment of the mitochondrial control region (d-loop) from 36 deer specimens of either sex recently harvested across the country, we have discovered 10 haplotypes belonging to 3 of the widely described European red deer lineages, or haplogroups: Iberian (A), Tyrrhenian (B), and Maraloid (E), clarifying the range limits of those lineages in the region. Combining this data with a comparative analysis of genetic diversity and historical records, we conclude that the Belarusian population of red deer has an artificially mixed origin, though it remains unclear how desirable such a state is, in terms of sustainable management, use, and conservation. Inquiries into ancient DNA are required to recognize the lineages closest to the autochthonous deer population of Belarus.