Genomic evidence for low genetic diversity but purging of strong deleterious variants in snow leopards

BACKGROUND

Long-term persistence of species with low genetic diversity is the focus of widespread attention in conservation biology. The snow leopard, Panthera uncia, is a big cat from high-alpine regions of Asia. However, its subspecies taxonomy, evolutionary history, evolutionary potential, and survival strategy remain unclear, which greatly hampers their conservation.

RESULTS

We sequence a high-quality chromosome-level genome of the snow leopard and the genomes of 52 wild snow leopards. Population genomics reveal the existence of two large genetic lineages in global snow leopards, the northern and southern lineages, supported by the biogeography. The Last Glacial Maximum drove the divergence of two lineages. Microclimate differences and large rivers between the western and central Himalayas likely maintain the differentiation of two lineages. EPAS1 is positively selected in the southern lineage with almost fixed amino acid substitutions and shows an increased allele frequency with elevation. Compared to the southern lineage, the northern lineage exhibits a lower level of genomic diversity and higher levels of inbreeding and genetic load, consistent with its recent population decline. We find that snow leopards have extremely low genomic diversity and higher inbreeding than other Carnivora species; however, strong deleterious mutations have been effectively purged in snow leopards by historical population bottlenecks and inbreeding, which may be a vital genetic mechanism for their population survival and viability.

CONCLUSIONS

Our findings reveal the survival strategy of a species with low genetic diversity and highlight the importance of unveiling both genetic diversity and genetic burden for the conservation of threatened species.

Reduced gene flow and bottleneck in the threatened giant armadillo (Priodontes maximus): implications for its conservation

The progressive fragmentation and loss of habitats represent the main threats for endangered species, causing genetic consequences that may have potential implications for a population's long-term persistence. Large mammals are the most affected species among vertebrates. The giant armadillo Priodontes maximus is a large South American mammal threatened species, showing nocturnal, solitary and fossorial behavior, occurring at low population densities, and its population dynamics are still poorly known. In this study, we carried out the first assessment of genetic variability and population genetic structure of the species, using a panel of 15 polymorphic microsatellites developed by high-throughput genome sequencing. The spatial Bayesian clustering, Fst and Dest results indicated the presence of two genetic clusters (K = 2) in the study area. These results suggest a reduction in gene flow between individuals inhabiting the Brazilian savanna (Cerrado) and the Pantanal wetlands, with the increased human-driven habitat modifications possibly contributing for this scenario. A bottleneck signal was detected in both populations, and a subpopulation structuring in the Cerrado may also be reflecting consequences of the extensive habitat modifications. Findings from this study provide important and useful information for the future maintenance of genetic diversity and long-term conservation of this flagship species.

Range-wide evolutionary relationships and historical demography of brown bears (Ursus arctos) revealed by whole-genome sequencing of isolated central Asian populations

Phylogeographic studies uncover hidden pathways of divergence and inform conservation. Brown bears (Ursus arctos) have one of the broadest distributions of all land mammals, ranging from Eurasia to North America, and are an important model for evolutionary studies. Although several whole genomes were available for individuals from North America, Europe and Asia, limited whole-genome data were available from Central Asia, including the highly imperilled brown bears in the Gobi Desert. To fill this knowledge gap, we sequenced whole genomes from nine Asian brown bears from the Gobi Desert of Mongolia, Northern Mongolia and the Himalayas of Pakistan. We combined these data with published brown bear sequences from Europe, Asia and North America, as well as other bear species. Our goals were to determine the evolutionary relationships among brown bear populations worldwide, their genetic diversity and their historical demography. Our analyses revealed five major lineages of brown bears based on a filtered set of 684,081 single nucleotide polymorphisms. We found distinct evolutionary lineages of brown bears in the Gobi, Himalayas, northern Mongolia, Europe and North America. The lowest level of genetic diversity and the highest level of inbreeding were found in Pakistan, the Gobi Desert and Central Italy. Furthermore, the effective population size (Ne ) for all brown bears decreased over the last 70,000 years. Our results confirm the genetic distinctiveness and ancient lineage of brown bear subspecies in the Gobi Desert of Mongolia and the Himalayas of Pakistan and highlight their importance for conservation.

Mid-Pleistocene Transitions Forced Himalayan ibex to Evolve Independently after Split into an Allopatric Refugium

Pleistocene glaciations had profound impact on the spatial distribution and genetic makeup of species in temperate ecosystems. While the glacial period trapped several species into glacial refugia and caused abrupt decline in large populations, the interglacial period facilitated population growth and range expansion leading to allopatric speciation. Here, we analyzed 40 genomes of four species of ibex and found that Himalayan ibex in the Pamir Mountains evolved independently after splitting from its main range about 0.1 mya following the Pleistocene species pump concept. Demographic trajectories showed Himalayan ibex experienced two historic bottlenecks, one each c. 0.8-0.5 mya and c. 50-30 kya, with an intermediate large population expansion c. 0.2-0.16 mya coinciding with Mid-Pleistocene Transitions. We substantiate with multi-dimensional evidence that Himalayan ibex is an evolutionary distinct phylogenetic species of Siberian ibex which need to be prioritized as Capra himalayensis for taxonomic revision and conservation planning at a regional and global scale.

A unique single nucleotide polymorphism in Agouti Signalling Protein (ASIP) gene changes coat colour of Sri Lankan leopard (Panthera pardus kotiya) to dark black

The Sri Lankan leopard (Panthera pardus kotiya) is an endangered subspecies restricted to isolated and fragmented populations in Sri Lanka. Among them, melanistic leopards have been recorded on a few occasions. Literature suggests the evolution of melanism several times in the Felidae family, with three species having distinct mutations. Nevertheless, the mutations or other variations in the remaining species, including Sri Lankan melanistic leopard, are unknown. We used reference-based assembled nuclear genomes of Sri Lankan wild type and melanistic leopards and de novo assembled mitogenomes of the same to investigate the genetic basis, adaptive significance, and evolutionary history of the Sri Lankan melanistic leopard. Interestingly, we identified a single nucleotide polymorphism in exon-4 Sri Lankan melanistic leopard, which may completely ablate Agouti Signalling Protein (ASIP) function. The wild type leopards in Sri Lanka did not carry this mutation, suggesting the cause for the occurrence of melanistic leopords in the population. Comparative analysis of existing genomic data in the literature suggests it as a P. p. kotiya specific mutation and a novel mutation in the ASIP-gene of the Felidae family, contributing to naturally occurring colour polymorphism. Our data suggested the coalescence time of Sri Lankan leopards at ~0.5 million years, sisters to the Panthera pardus lineage. The genetic diversity was low in Sri Lankan leopards. Further, the P. p. kotiya melanistic leopard is a different morphotype of the P. p. kotiya wildtype leopard resulting from the mutation in the ASIP-gene. The ability of black leopards to camouflage, along with the likelihood of recurrence and transfer to future generations, suggests that this rare mutation could be environment-adaptable.

From poops to planning: A broad non-invasive genetic survey of large mammals from the Indian Himalayan Region

Large forested landscapes often harbour significant amount of biodiversity and support mankind by rendering various livelihood opportunities and ecosystem services. Their periodic assessment for health and ecological integrity is essential for timely mitigation of any negative impact of human use due to over harvesting of natural resources or unsustainable developmental activities. In this context, monitoring of mega fauna may provide reasonable insights about the connectivity and quality of forested habitats. In the present study, we conducted a largest non-invasive genetic survey to explore mammalian diversity and genetically characterized 13 mammals from the Indian Himalayan Region (IHR). We analyzed 4806 faecal samples using 103 autosomal microsatellites and with three mitochondrial genes, we identified 37 species of mammal. We observed low to moderate level of genetic variability and most species exhibited stable demographic history. We estimated an unbiased population genetic account (PGA_unbias) for 13 species that may be monitored after a fixed time interval to understand species performance in response to the landscape changes. The present study has been evident to show pragmatic permeability with the representative sampling in the IHR in order to facilitate the development of species-oriented conservation and management programmes.

Chromosome-level Genome Assembly of the High-altitude Leopard (Panthera pardus) Sheds Light on Its Environmental Adaptation

The leopard (Panthera pardus) has the largest natural distribution from low- to high-altitude areas of any wild felid species, but recent studies have revealed that leopards have disappeared from large areas, probably owing to poaching, a decline of prey species, and habitat degradation. Here, we reported the chromosome-scale genome assembly of the high-altitude leopard (HL) based on nanopore sequencing and high-throughput chromatin conformation capture (Hi-C) technology. Panthera genomes revealed similar repeat composition, and there was an appreciably conserved synteny between HL and the other two Panthera genomes. Divergence time analysis based on the whole genomes revealed that the HL and the low-altitude leopard differentiate from a common ancestor ∼2.2 Ma. Through comparative genomics analyses, we found molecular genetic signatures that may reflect high-altitude adaptation of the HL. Three HL-specific missense mutations were detected in two positively selected genes, that is, ITGA7 (Ala112Gly, Asp113Val, and Gln115Pro) and NOTCH2 (Ala2398Ser), which are likely to be associated with hypoxia adaptation. The chromosome-level genome of the HL provides valuable resources for the investigation of high-altitude adaptation and protection management of the vulnerable leopard.

Individual Identification of Large Felids in Field Studies: Common Methods, Challenges, and Implications for Conservation Science

Large felids represent some of the most threatened large mammals on Earth, critical for both tourism economies and ecosystem function. Most populations are in a state of decline, and their monitoring and enumeration is therefore critical for conservation. This typically rests on the accurate identification of individuals within their populations. We review the most common and current survey methods used in individual identification studies of large felid ecology (body mass > 25 kg). Remote camera trap photography is the most extensively used method to identify leopards, snow leopards, jaguars, tigers, and cheetahs which feature conspicuous and easily identifiable coat patterning. Direct photographic surveys and genetic sampling are commonly used for species that do not feature easily identifiable coat patterning such as lions. We also discuss the accompanying challenges encountered in several field studies, best practices that can help increase the precision and accuracy of identification and provide generalised ratings for the common survey methods used for individual identification.

Comparative Genomics of the Major Histocompatibility Complex (MHC) of Felids

This review summarizes the current knowledge on the major histocompatibility complex (MHC) of the family Felidae. This family comprises an important domestic species, the cat, as well as a variety of free-living felids, including several endangered species. As such, the Felidae have the potential to be an informative model for studying different aspects of the biological functions of MHC genes, such as their role in disease mechanisms and adaptation to different environments, as well as the importance of genetic diversity for conservation issues in free-ranging or captive populations. Despite this potential, the current knowledge on the MHC in the family as a whole is fragmentary and based mostly on studies of the domestic cat and selected species of big cats. The overall structure of the domestic cat MHC is similar to other mammalian MHCs following the general scheme "centromere-MHC class I-MHC class III-MHC class II" with some differences in the gene contents. An unambiguously defined orthologue of the non-classical class I HLA-E gene has not been identified so far and the class II DQ and DP genes are missing or pseudogenized, respectively. A comparison with available genomes of other felids showed a generally high level of structural and sequence conservation of the MHC region. Very little and fragmentary information on in vitro and/or in vivo biological functions of felid MHC genes is available. So far, no association studies have indicated effects of MHC genetic diversity on a particular disease. No information is available on the role of MHC class I molecules in interactions with Natural Killer (NK) cell receptors or on the putative evolutionary interactions (co-evolution) of the underlying genes. A comparison of complex genomic regions encoding NK cell receptors (the Leukocyte Receptor Complex, LRC and the Natural Killer Cell Complex, NKC) in the available felid genomes showed a higher variability in the NKC compared to the LRC and the MHC regions. Studies of the genetic diversity of domestic cat populations and/or specific breeds have focused mainly on DRB genes. Not surprisingly, higher levels of MHC diversity were observed in stray cats compared to pure breeds, as evaluated by DRB sequencing as well as by MHC-linked microsatellite typing. Immunogenetic analysis in wild felids has only been performed on MHC class I and II loci in tigers, Namibian leopards and cheetahs. This information is important as part of current conservation tasks to assess the adaptive potential of endangered wild species at the human-wildlife interface, which will be essential for preserving biodiversity in a functional ecosystem.

Horizon Scan of Transboundary Concerns Impacting Snow Leopard Landscapes in Asia

The high-altitude region of Asia is prone to natural resource degradation caused by a variety of natural and anthropogenic factors that also threaten the habitat of critical top predator species, the snow leopard (Panthera uncia). The snow leopard’s landscape encompasses parts of the twelve Asian countries and is dominated by pastoral societies within arid mountainous terrain. However, no investigation has assessed the vulnerability and pathways towards long-term sustainability on the global snow leopard landscape scale. Thus, the current study reviewed 123 peer-reviewed scientific publications on the existing knowledge, identified gaps, and proposed sustainable mitigation options for the longer term and on larger landscape levels in the range countries. The natural resource degradation in this region is caused by various social, economic, and ecological threats that negatively affect its biodiversity. The factors that make the snow leopard landscapes vulnerable include habitat fragmentation through border fencing, trade corridor infrastructure, non-uniform conservation policies, human–snow leopard conflict, the increasing human population, climatic change, land use and cover changes, and unsustainable tourism. Thus, conservation of the integrated Socio-Ecological System (SES) prevailing in this region requires a multi-pronged approach. This paper proposes solutions and identifies the pathways through which to implement these solutions. The prerequisite to implementing such solutions is the adoption of cross-border collaboration (regional cooperation), the creation of peace parks, readiness to integrate transnational and cross-sectoral conservation policies, a focus on improving livestock management practices, a preparedness to control human population growth, a readiness to mitigate climate change, initiating transboundary landscape-level habitat conservation, adopting environment-friendly trade corridors, and promoting sustainable tourism. Sustainable development in this region encompasses the political, social, economic, and ecological landscapes across the borders.

Analysis of Conservation Gaps and Landscape Connectivity for Snow Leopard in Qilian Mountains of China

Human modification and habitat fragmentation have a substantial influence on large carnivores, which need extensive, contiguous habitats to survive in a landscape. The establishment of protected areas is an effective way to offer protection for carnivore populations by buffering them from anthropogenic impacts. In this study, we used MaxEnt to model habitat suitability and to identify conservation gaps for snow leopard (Panthera uncia) in the Qilian Mountains of China, and then assessed the impact of highways/railways and their corridors on habitat connectivity using a graph-based landscape connectivity model. Our results indicated that the study area had 51,137 km2 of potentially suitable habitat for snow leopards and that there were four protection gaps outside of Qilian Mountain National Park. The findings revealed that the investigated highway and railway resulted in a decrease in connectivity at a regional scale, and that corridor development might enhance regional connectivity, which strengthens the capacity of central habitat patches to act as stepping stones and improve connections between western and eastern habitat patches. This study emphasized the need for assessing the impact of highways and railways, as well as their role in corridor development, on species’ connectivity. Based on our results, we provide some detailed recommendations for designing protection action plans for effectively protecting snow leopard habitat and increasing habitat connectivity.

Evidence of spatial genetic structure in a snow leopard population from Gansu, China

Understanding the spatial structure of genetic diversity provides insights into a populations' genetic status and enables assessment of its capacity to counteract the effects of genetic drift. Such knowledge is particularly scarce for the snow leopard, a conservation flagship species of Central Asia mountains. Focusing on a snow leopard population in the Qilian mountains of Gansu Province, China, we characterised the spatial genetic patterns by incorporating spatially explicit indices of diversity and multivariate analyses, based on different inertia levels of Principal Component Analysis (PCA). We compared two datasets differing in the number of loci and individuals. We found that genetic patterns were significantly spatially structured and were characterised by a broad geographical division coupled with a fine-scale cline of differentiation. Genetic admixture was detected in two adjoining core areas characterised by higher effective population size and allelic diversity, compared to peripheral localities. The power to detect significant spatial relationships depended primarily on the number of loci, and secondarily on the number of PCA axes. Spatial patterns and indices of diversity highlighted the cryptic structure of snow leopard genetic diversity, likely driven by its ability to disperse over large distances. In combination, the species' low allelic richness and large dispersal ability result in weak genetic differentiation related to major geographical features and isolation by distance. This study illustrates how cryptic genetic patterns can be investigated and analysed at a fine spatial scale, providing insights into the spatially variable isolation effects of both geographic distance and landscape resistance.

MORTALITY REVIEW FOR THE NORTH AMERICAN SNOW LEOPARD (PANTHERA UNCIA) ZOO POPULATION FROM JANUARY 1999 TO DECEMBER 2019

The objective of this 20-yr retrospective study was to review and summarize causes of mortality in the North American (NA) snow leopard population to inform and enhance animal health and husbandry practices. Pathology reports were requested from all NA zoological institutions housing snow leopards that died between 01 January 1999 and 31 December 2019. Data were reviewed and cause of death (COD) and concurrent diseases were summarized and compared by age group, organ system, and disease process. The 241 snow leopards in this report include 109 males, 130 females, and two of undetermined sex. Among them were 116 geriatric snow leopards (>15 yr), 72 adults (15-3 yr), 16 juveniles (3 yr to 2 mo), 32 neonates (2 mo to 0 days), and five fetuses (<0 days). Overall, noninfectious diseases were the most common COD across all age groups (73%). In adult and geriatric snow leopards, chronic renal disease (CRD) (38.8%) and malignant neoplasia (19.7%), including oral squamous cell carcinoma (6.4%), were a common COD. In juveniles and neonates, perinatal death and congenital diseases, including ocular coloboma (15.6%), were a common COD. Individuals with CRD were 13.5 and 4.36 times more likely to have veno-occlusive disease and cardiac fibrosis, respectively. Snow leopards with urolithiasis were 5.27 times more likely to have CRD. Infectious (14.1%) and inflammatory diseases (8.7%) for which no specific etiology was identified were less common overall and more common in juveniles and neonates (25% and 21%, respectively). Neoplasms not previously reported in snow leopards or that are generally uncommon in the veterinary literature included transitional cell carcinoma of the urinary bladder (n = 7) and mesothelioma (n = 1).

Characterization of Olfactory Receptor Repertoires in the Endangered Snow Leopard Based on the Chromosome-Level Genome

Olfaction is a complicated process that begins with the specific binding of volatile odorant molecules to dedicated olfactory receptors (ORs) in the olfactory epithelium and plays a pivotal role in the survival of mammals. The OR subgenome of the snow leopard has remained largely unexplored, and thus, investigation of the OR system would shed light on the evolutionary dynamics of the snow leopard OR repertoires and genetic evidence for environmental adaptation. In this study, we conducted genome-wide identification and characterization of OR genes in the snow leopard and compared them to all other Panthera species. A total of 213, 294, 624, 305, and 253 functional OR genes were identified in the snow leopard, lion, jaguar, leopard, and tiger, respectively. The phylogenetic relationships of functional Panthera OR genes were illustrated, which comprised 69 families and 350 subfamilies distributed in two classes (Class I and Class II). Comparative analysis of the five Panthera species indicated 115 shared and 5 snow leopard-specific clusters. The potential odorant specificity of certain snow leopard OR genes was identified by similarities to human protein sequences and we identified odorants such as eugenol methyl ether that had the most OR genes. Since our references for odorants were from human studies, possible odorants from snow leopard-specific OR genes need further investigation. The lowest number of OR genes for the snow leopard among Panthera species possibly revealed the association between OR gene family contraction and high-altitude adaptation, which needed further and deeper investigation. This systematic study of OR genes in the snow leopard will provide a solid foundation for further study of olfactory function and variation in the snow leopard.

Implications of landscape genetics and connectivity of snow leopard in the Nepalese Himalayas for its conservation

The snow leopard is one of the most endangered large mammals. Its population, already low, is declining, most likely due to the consequences of human activity, including a reduction in the size and number of suitable habitats. With climate change, habitat loss may escalate, because of an upward shift in the tree line and concomitant loss of the alpine zone, where the snow leopard lives. Migration between suitable areas, therefore, is important because a decline in abundance in these areas may result in inbreeding, fragmentation of populations, reduction in genetic variation due to habitat fragmentation, loss of connectivity, bottlenecks or genetic drift. Here we use our data collected in Nepal to determine the areas suitable for snow leopards, by using habitat suitability maps, and describe the genetic structure of the snow leopard within and between these areas. We also determine the influence of landscape features on the genetic structure of its populations and reveal corridors connecting suitable areas. We conclude that it is necessary to protect these natural corridors to maintain the possibility of snow leopards’ migration between suitable areas, which will enable gene flow between the diminishing populations and thus maintain a viable metapopulation of snow leopards.

Is there low maternal genetic variation in West Asian populations of leopard?

Persian leopards Panthera pardus saxicolor have been extirpated from over 84% of their historic range and are now limited to rugged landscapes of West Asia and the Caucasus. Understanding and maintaining genetic diversity and population connectivity is important for preventing inbreeding and genetic drift, both of which can threaten population viability. All previous analyses of intraspecific genetic variation of West Asian leopards based on the NADH dehydrogenase subunit 5 gene have reported low mitogenomic diversity. In the current study, we sequenced 959 bp of the mtDNA cytochrome b gene to describe the spatial genetic structure of 22 wild Persian leopards across Iran, which hosts most of the subspecies extant range. The findings based on phylogenetic trees and median-joining network indicated that leopards from Iran formed a distinct subclade, i.e., P. p. saxicolor. The AMOVA analysis showed significant differentiation (88.55%) between the subclades of Persian leopards and other Asian leopards. The lowest levels of haplotype (0.247) and nucleotide (0.00078) diversity were estimated in Persian leopards from Iran. Mitochondrial genome sequencing revealed only two closely related haplotypes. There was no evidence for recent sudden demographic expansion scenario in Persian leopards. The low diversity in cytochrome b gene could potentially be brought about by selective pressure on mitochondria to adapt to oxidative stress and higher metabolic rates in cold environments.

Revisiting the Woolly wolf (Canis lupus chanco) phylogeny in Himalaya: Addressing taxonomy, spatial extent and distribution of an ancient lineage in Asia

Of the sub-species of Holarctic wolf, the Woolly wolf (Canis lupus chanco) is uniquely adapted to atmospheric hypoxia and widely distributed across the Himalaya, Qinghai Tibetan Plateau (QTP) and Mongolia. Taxonomic ambiguity still exists for this sub-species because of complex evolutionary history anduse of limited wild samples across its range in Himalaya. We document for the first time population genetic structure and taxonomic affinity of the wolves across western and eastern Himalayan regions from samples collected from the wild (n = 19) using mitochondrial control region (225bp). We found two haplotypes in our data, one widely distributed in the Himalaya that was shared with QTP and the other confined to Himachal Pradesh and Uttarakhand in the western Himalaya, India. After combining our data withpublished sequences (n = 83), we observed 15 haplotypes. Some of these were shared among different locations from India to QTP and a few were private to geographic locations. A phylogenetic tree indicated that Woolly wolves from India, Nepal, QTP and Mongolia are basal to other wolves with shallow divergence (K2P; 0.000-0.044) and high bootstrap values. Demographic analyses based on mismatch distribution and Bayesian skyline plots (BSP) suggested a stable population over a long time (~million years) with signs of recent declines. Regional dominance of private haplotypes across its distribution range may indicate allopatric divergence. This may be due to differences in habitat characteristics, availability of different wild prey species and differential deglaciation within the range of the Woolly wolf during historic time. Presence of basal and shallow divergence within-clade along with unique ecological requirements and adaptation to hypoxia, the Woolly wolf of Himalaya, QTP, and Mongolian regions may be considered as a distinct an Evolutionary Significant Unit (ESU). Identifying management units (MUs) is needed within its distribution range using harmonized multiple genetic data for effective conservation planning.

A pilot study-genetic diversity and population structure of snow leopards of Gilgit-Baltistan, Pakistan, using molecular techniques

Background

The Hindu Kush and Karakoram mountain ranges in Pakistan's northern areas are a natural habitat of the snow leopard (Panthera uncia syn. Uncia uncia) but the ecological studies on this animal are scarce since it is human shy by nature and lives in difficult mountainous tracts. The pilot study is conducted to exploit the genetic diversity and population structure of the snow leopard in this selected natural habitat of the member of the wildcat family in Pakistan.

Method

About 50 putative scat samples of snow leopard from five localities of Gilgit-Baltistan (Pakistan) along with a control sample of zoo maintained male snow leopard were collected for comparison. Significant quality and quantity of genomic DNA was extracted from scat samples using combined Zhang-phenol-chloroform method and successful amplification of cytochrome c oxidase I gene (190 bp) using mini-barcode primers, seven simple sequence repeats (SSR) markers and Y-linked AMELY gene (200 bp) was done.

Results

Cytochrome c oxidase I gene sequencing suggested that 33/50 (66%) scat samples were of snow leopard. AMELY primer suggested that out of 33 amplified samples, 21 (63.63%) scats were from male and 12 (36.36%) from female leopards. Through successful amplification of DNA of 25 out of 33 (75.75%) scat samples using SSR markers, a total of 68 alleles on seven SSR loci were identified, showing low heterozygosity, while high gene flow between population.

Discussion

The low gene flow rate among the population results in low genetic diversity causing decreased diversification. This affects the adaptability to climatic changes, thus ultimately resulting in decreased population size of the species.

Genetic diversity, inbreeding and cancer

Genetic diversity is essential for adaptive capacities, providing organisms with the potential of successfully responding to intrinsic and extrinsic challenges. Although a clear reciprocal link between genetic diversity and resistance to parasites and pathogens has been established across taxa, the impact of loss of genetic diversity by inbreeding on the emergence and progression of non-communicable diseases, such as cancer, has been overlooked. Here we provide an overview of such associations and show that low genetic diversity and inbreeding associate with an increased risk of cancer in both humans and animals. Cancer being a multifaceted disease, loss of genetic diversity can directly (via accumulation of oncogenic homozygous mutations) and indirectly (via increased susceptibility to oncogenic pathogens) impact abnormal cell emergence and escape of immune surveillance. The observed link between reduced genetic diversity and cancer in wildlife may further imperil the long-term survival of numerous endangered species, highlighting the need to consider the impact of cancer in conservation biology. Finally, the somewhat incongruent data originating from human studies suggest that the association between genetic diversity and cancer development is multifactorial and may be tumour specific. Further studies are therefore crucial in order to elucidate the underpinnings of the interactions between genetic diversity, inbreeding and cancer.

Assessment of habitat suitability of the snow leopard (Panthera uncia) in Qomolangma National Nature Reserve based on MaxEnt modeling

Habitat evaluation constitutes an important and fundamental step in the management of wildlife populations and conservation policy planning. Geographic information system (GIS) and species presence data provide the means by which such evaluation can be done. Maximum Entropy (MaxEnt) is widely used in habitat suitability modeling due to its power of accuracy and additional descriptive properties. To survey snow leopard populations in Qomolangma (Mt. Everest, QNNR) National Nature Reserve, Tibet, China, we pooled 127 pugmarks, 415 scrape marks, and 127 non-invasive identifications of the animal along line transects and recorded 87 occurrences through camera traps from 2014-2017. We adopted the MaxEnt model to generate a map highlighting the extent of suitable snow leopard habitat in QNNR. Results showed that the accuracy of the MaxEnt model was excellent (mean AUC=0.921). Precipitation in the driest quarter, ruggedness, elevation, maximum temperature of the warmest month, and annual mean temperature were the main environmental factors influencing habitat suitability for snow leopards, with contribution rates of 20.0%, 14.4%, 13.3%, 8.7%, and 8.2% respectively. The suitable habitat area extended for 7001.93 km2, representing 22.72% of the whole reserve. The regions bordering Nepal were the main suitable snow leopard habitats and consisted of three separate habitat patches. Our findings revealed that precipitation, temperature conditions, ruggedness, and elevations of around 4000 m influenced snow leopard preferences at the landscape level in QNNR. We advocate further research and cooperation with Nepal to evaluate habitat connectivity and to explore possible proxies of population isolation among these patches. Furthermore, evaluation of subdivisions within the protection zones of QNNR is necessary to improve conservation strategies and enhance protection.

Genome-Wide Evolutionary Analysis of Natural History and Adaptation in the World's Tigers

No other species attracts more international resources, public attention, and protracted controversies over its intraspecific taxonomy than the tiger (Panthera tigris) [1, 2]. Today, fewer than 4,000 free-ranging tigers survive, covering only 7% of their historical range, and debates persist over whether they comprise six, five, or two subspecies [3-6]. The lack of consensus over the number of tiger subspecies has partially hindered the global effort to recover the species from the brink of extinction, as both captive breeding and landscape intervention of wild populations increasingly require an explicit delineation of the conservation management units [7]. The recent coalescence to a late Pleistocene bottleneck (circa 110 kya) [5, 8, 9] poses challenges for detecting tiger subspecific morphological traits, suggesting that elucidating intraspecific evolution in the tiger requires analyses at the genomic scale. Here, we present whole-genome sequencing analyses from 32 voucher specimens that resolve six statistically robust monophyletic clades corresponding to extant subspecies, including the recently recognized Malayan tiger (P. tigris jacksoni). The intersubspecies gene flow is very low, corroborating the recognized phylogeographic units. We identified multiple genomic regions that are candidates for identifying the adaptive divergence of subspecies. The body-size-related gene ADH7 appears to have been strongly selected in the Sumatran tiger, perhaps in association with adaptation to the tropical Sunda Islands. The identified genomic signatures provide a solid basis for recognizing appropriate conservation management units in the tiger and can benefit global conservation strategic planning for this charismatic megafauna icon.

Presence of the snow leopard Panthera uncia confirmed at four sites in the Chinese Tianshan Mountains

The Endangered snow leopard Panthera uncia is a flagship species of mountainous central Asia, and a conservation concern. China has the largest extent of potential snow leopard habitat and is thus crucial for snow leopard conservation. There are many challenges to snow leopard conservation in China, however, and there is still little information on the species for many geographical locations, including the Tianshan Mountains of Xinjiang province, which are important because they potentially connect snow leopard populations in Krygyzstan and Kazakhstan with those in Mongolia. We used camera traps in four areas across eastern, central and western Tianshan, with a total survey effort of 3,216 camera-trapping days. We confirmed the presence of snow leopards and an abundance of potential snow leopard prey, including the Siberian ibex Capra sibirica, in all areas. We found 2–3 individual adult snow leopards at each site, with relatively limited survey effort, and more study is needed to fully investigate the importance of the Tianshan Mountains for the species. Establishing more protected areas is essential for snow leopard conservation, and we have used data from this study to apply for protected area status for several areas.