Mammalian Biology最新文献

Defining species within the Canidae family is challenging due to morphological convergence, behavioral plasticity, traditional taxonomic limitations, and possible hybridisation. This challenge is timely with the recent population and range expansion of the golden jackal (Canis aureus). Exploring their morphological data and sexual dimorphism is essential for identifying factors driving their success in new habitats. The proven hybridization of golden jackals with dogs and wolves may affect species description, population dynamics, and genetic diversity, impacting conservation strategies. This study, for the first time, conducts a morphometric analysis of golden jackals in Somogy County, Hungary, to prove sexual size dimorphism (SSD) in body and skull and sexual shape dimorphism (SShD) in skull across juvenile and adult age groups. 719 golden jackals (362 females and 357 males) were collected between January 2021 and January 2023. Descriptive statistics revealed significant SSD in body and skull measurements among both age groups, with males generally larger than females, particularly in body mass (11.72% in juveniles and 13.37% in adults). Most skull dimensions differed significantly between sexes and age groups, except for foramen magnum height, foramen magnum width, and postorbital breadth among juveniles and foramen magnum height and postorbital breadth among adults. We used principal component analyses (PCA) on raw dimension data and the log shape ratio method to extract shape information. Linear discriminant analysis (LDA) explored skull SShD between sexes. Notably, our study achieved over 71% accuracy in sex classification, illustrating the clear presence of SShD of the skull in golden jackals across both age groups. Our study provides a comprehensive database of golden jackals in the overpopulated Hungarian habitat, which will be helpful for further research on ecology, behavior, and conservation management.

The blackbuck (Antilope cervicapra) is endemic to the Indian subcontinent. It occurs in a wide variety of habitats that range from open plains, grasslands, scrublands, and lightly forested areas. The current study provides insights into the existing genetic variation in blackbuck populations, which is crucial for enhancing population fitness and long-term survival. To understand the phylogeny and genetic diversity of blackbuck, we processed the pellet samples (n = 233) from 18 locations across their distribution range in India for MtDNACytb and control region. High haplotype (0.991) and nucleotide diversity (0.033) were observed in the populations. The mtDNA-based AMOVA indicated 41.73% genetic variations among the blackbuck populations of India. The results confirmed that the blackbuck has a unique haplotype in different locations that is not shared by other populations. Geographically, our results identified four genetically distinct clusters: Northern, Southern East, Southern West and Eastern central regions of India. The study reveals that an ancestral population initially separated into two groups, leading to the formation of the North and South clusters. Subsequently, the South population diverged further into three clusters: Southeast, Southwest, and Eastern-central populations. Neighbor-joining analysis suggested the Eastern-central region as part of the Southern East region, while Bayesian phylogeny indicated a separate clade emerging from the Eastern-central region at a later time. Bayesian skyline plots revealed a history of population equilibrium in the Northern region followed by a recent population expansion in Southern East, Southern West and Eastern-central regional populations. Demographic analysis suggests that blackbucks have effectively adapted to their respective landscapes.

The Eurasian wild boar (Sus scrofa), having faced a population size reduction during the nineteenth and early twentieth centuries, is now experiencing a remarkable population recovery, not only confined to natural habitats alone, but also thriving in human-dominated environments. Previously, studies on wild boars predominantly relied on the analysis of supposedly neutral molecular markers (e.g., microsatellites and single nucleotide polymorphisms). In this study, a next-generation sequencing approach was used to examine the adaptive variation at the second exon of the SLA-DRB1 locus in 116 wild boars from the western Balkans. A total of 17 functional SLA-DRB1 alleles were detected which translated into 14 different amino-acid sequences. In 12 individuals, we observed alleles at duplicated SLA-DRB1 loci. Spatial analysis revealed the presence of three genetic clusters, albeit with relatively low overall differentiation (an average F_ST value of 0.012). Positive selection was detected on only one codon, as indicated by multiple tests, while the presence of shared alleles among related species suggested signals of trans-species polymorphism. Our results indicate the high MHC diversity at the SLA-DRB1 locus in wild boars from the Balkan Peninsula, shaped by a complex interplay of several non-exclusive mechanisms, including balancing selection, recombination, and gene duplications.

The hispid hare, an endangered elusive mammal that dwells in the tall grasslands of the Himalayan foothills across in Nepal, India, and Bhutan is facing severe threats from anthropogenic activities and seasonal floods. Previous studies on hispid hare have investigated in Shuklaphanta National Park, only a study has been conducted in Bardia National Park over the past decade. We aim to evaluate current distribution pattern of the hispid hare in the Babai valley in Bardia National Park, identify factors influencing their distribution, and access existing threats. We surveyed 428 transects (50 m × 2 m) across 1048.55 hectares of grasslands in the valley pre-burn and post-burn. The hispid hare exhibited a clumped distribution pattern, with recorded pellets in six grasslands: Kalinara, Guthi, Sano Shree Phanta, Chitaale Phanta, Ratomate, Rhino Release Site, and Mulghat in Bardia National Park. Pellet density was higher in post-burn, indicating a greater population density in summer compared to winter. Our finding revealed a preference grasslands area close to riverbank in pre-burn and short grasslands in post-burn, while the species tended to avoid forests and edge between grasslands and forests. The best-fit model highlighted that grass density, grasslands burn, and annual precipitation significantly influence the distribution of the hispid hare. Major threats identified in the field included grasslands burn, flood, invasive species, vegetation succession, and predators. We recommend that conservation efforts focus on protecting and managing grasslands that provide suitable habitat for the hispid hare.

Knowledge of behaviors surrounding reproduction in wild species is essential to the development of effective management and conservation strategies. Many carnivores use dens to increase the safety and survival of their neonatal young while females shift to central-place foraging to meet the energetic demands of raising young. Caracals (Caracal caracal), a medium-size wild cat, have a widespread geographic distribution but limited information from minimal observations exists on the behaviors associated with denning and caring for young. We report observations of dens used by four caracals in the surrounds of Cape Town, South Africa, including the duration of den use, maternal home ranges, and movements away from dens. Three of four females established denning in September and one in December, suggesting a birth pulse during the Southern Hemisphere spring and summer. Of seven den sites we documented, six were in dense shrubland fynbos vegetation and one among boulders; all of which had thick overhead cover. Females and neonatal young used 1–3 primary dens for approximately six weeks, followed by the use of short-term auxiliary dens. Female maternal home ranges were approximately 31% the size of their home ranges estimated using all their data. Trips away from the dens averaged 12 h while the average maximum distances across all trips away from dens for each female was 1135 m (range = 801–1327 m). Our observations inform our understanding of the timing and physical characteristics of caracal dens and help fill research gaps on the natural history of caracal denning behavior.

The Ethiopian highlands represent a wide spectrum of ecological gradients that provide suitable conditions for gradient speciation. Previous studies support the gradient model of speciation for two Ethiopian shrew species: Crocidura thalia and C. glassi. Here, we aimed to elucidate for the first time the phylogenetic position of C. afeworkbekelei and to test the gradient model of speciation for these three species. On the basis of a dataset collected from the whole south slope of the Bale Mountains, we reconstructed phylogenetic relationships among these species using mitochondrial and nuclear markers. Additionally, we examined shape and size differentiation of the skull and mandible. The molecular data revealed a similarity of the three species with lack of reciprocal monophyly among them. We demonstrated differences both in size and shape of the skull and mandible between low- and high-elevation forms albeit without a significant morphological hiatus. We identified the most changeable parts of the skull and mandible, which imply adaptive shifts in diet. We revealed the distribution, phylogenetic and morphological patterns that match predictions of the gradient model of speciation for three mammalian forms. Our data suggest intense processes of adaptation to the markedly different habitats along the considerable altitudinal gradient that fit the first stage of the gradient model of speciation. We believe that C. afeworkbekelei and C. thalia should be regarded as different ecotypes, and these species names must be reduced to junior synonyms of C. glassi.

The scaling relationship between digestive system and body mass shapes foraging strategies in herbivores. The Jarman–Bell principle and the forage maturation hypothesis (FMH), two of the most important predictions formulated in herbivore foraging ecology, have been used to explain this relationship.We aimed to test these predictions for the largest European herbivore—the European bison-which is highly sexually dimorphic and recognised as a refugee species in non-optimal forest habitats. We conducted our study in the Białowieża Primeval Forest, where the European bison has been recognized as a refugee species. We estimated vegetation quality and biomass along the foraging paths of male and female European bison, and the vegetation biomass at random points in different habitats and months. We found no support for the Jarmann-Bell principle at the intraspecific level in European bison, as males and females foraged on patches of similar crude protein and fibre content. However, females selected for higher biomass. The quality of vegetation on the bison foraging patches showed a significant spatio-temporal variation. It increased from May to July and then gradually decreased. It also increased with the fertility and wetness of the habitats being the highest in wet forests. Mean biomass on European bison foraging patches (131.5 g/m²), was significantly lower than on random plots (210.5 g/m²), which supported the FMH. Our study suggests that in rich forest habitats, the abundant food resources available in summer may not constrain the metabolic rate/gut capacity ratio of either sex, potentially leading to dietary segregation. In contrast to open habitats, where vegetation maturation is less temporally variable, European bison in rich forest habitats may optimise patch selection and energy intake by tracking a habitat- and species-specific changes in the plant phenology. Understanding the relationship between European bison forage selection and forage nutritional constraints in forest habitats may be critical for conservation programmes, as European bison are better adapted to more open habitats and are recognised as refugee species in suboptimal forest habitats.

Giraffes exhibit a large sexual dimorphism in body size. Whether sexual dimorphisms also exist in body proportions of the axial and appendicular skeleton has been debated, particularly regarding the giraffe’s iconic long neck. We examined the anatomical proportions of the neck, forelegs, hindlegs, and body trunk of the Masai giraffe (G. tippelskirchi) in captive and wild populations. We found that female Masai giraffes have proportionally longer necks relative to their forelegs than males in contradiction to the original necks-for-sex hypothesis that proposed that the evolution of the giraffe’s long neck was driven by male-male competition. However, male neck width and apparent mass are proportionally larger than females’, supporting a modification of the necks-for-sex hypothesis. Moreover, male foreleg length is proportionally longer whereas female trunk length is proportionally longer. These sexual dimorphisms were found in both captive and wild Masai giraffes. We speculate that the initial evolution of the giraffe’s long neck and legs was driven by interspecific competition and the maternal nutritional demands of gestation and lactation through natural selection to gain a competitive advantage in browsing, and then later the neck mass was further increased as a consequence of male-male competition and sexual selection. Differences in the proportions of major body components define sex phenotypes, but several giraffes display opposite-sex phenotypes with a significantly higher level of discordancy seen in captive males. We speculate that body proportion sexual dimorphisms are maintained in the wild by natural and/or sexual selection, but in captivity selection is relaxed resulting in a higher occurrence of discordances in sexual phenotypes.

Paca (Cuniculus paca) is a medium-sized caviomorph rodent that plays an important role in the dynamics of plant and animal diversity in Neotropical forests. Despite being a generalist species, habitat use can be influenced by the availability of resources, cover, and shelter, but also by the landscape of fear. We investigated whether paca habitat use is mainly driven by resource availability and/or the landscape of fear in a spatiotemporal context in the Atlantic Forest montane of Brazil. We used camera traps and generalized least squares models to investigate the influence of lunar phases on the modulation of environmental factors in paca habitat use and the effects on the prey–predator activity pattern. The availability of food resources, specifically Juçara palm (Euterpe edulis) and Paraná pine (Araucaria angustifolia), was the best predictor to explain paca habitat use, regardless of moonlight. These threatened and dominant trees provide keystone resources for paca safely and efficiently in the study area. However, we found that moonlight can alter the importance of the effect of its main predator (Puma concolor), on the spatiotemporal use of the paca. The risk of predation has a greater impact on the paca's habitat use during phases of intense moonlight, and as an anti-predation strategy, the paca changes its activity pattern precisely during these periods. Although the conservation status of the paca is of least concern, our results have highlighted its important ecosystem role in Neotropical forests, interacting strongly with key and threatened species of the Atlantic Forest.

Sound management of coastal resources is based on science-based decisions. Bottlenose dolphins are found around Puerto Rico; however, limited information exists on the ecology, behavior, sex ratio, distribution patterns, and population structure presenting, challenges in managing the bottlenose dolphin as defined in the Marine Mammal Protection Act of 1972. We sequenced the mitochondrial control region (mtDNA-CR) of 27 live and 11 stranded dolphins from Puerto Rico, five stranded dolphins from Guadeloupe and included sequences from the North Atlantic and the Pacific Ocean. Our genetic data from the new samples indicates the presence of distinct genetic lineages (inshore—represented by coastal individuals) and worldwide-distributed form (represented by both coastal and offshore individuals) in Puerto Rico. DNA divergence between inshore/coastal and offshore haplotypes ranged from 4.34 to 6.58%. All haplotypes from Puerto Rico have been previously reported from the Caribbean and North Atlantic. Genetic analysis yielded a complex population structure without a clear geographic signal; an expected result from a highly mobile marine mammal. A clade consisting exclusively of coastal dolphins of the Caribbean and the western North Atlantic was recovered. Offshore haplotypes from the eastern and western North Atlantic were generally clustered with offshore haplotypes of the Caribbean. Coastal and offshore haplotypes from the Pacific differed from those from the Atlantic. When we partitioned the data by form (coastal vs. offshore) and ocean (Atlantic vs. Pacific), we detected significant population differentiation (F_ST = 0.4089), indicating limited gene flow between forms and across oceans.