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1.
Species conservation can be improved by knowledge of evolutionary and genetic history. Tigers are among the most charismatic of endangered species and garner significant conservation attention. However, their evolutionary history and genomic variation remain poorly known, especially for Indian tigers. With 70% of the world’s wild tigers living in India, such knowledge is critical. We re-sequenced 65 individual tiger genomes representing most extant subspecies with a specific focus on tigers from India. As suggested by earlier studies, we found strong genetic differentiation between the putative tiger subspecies. Despite high total genomic diversity in India, individual tigers host longer runs of homozygosity, potentially suggesting recent inbreeding or founding events, possibly due to small and fragmented protected areas. We suggest the impacts of ongoing connectivity loss on inbreeding and persistence of Indian tigers be closely monitored. Surprisingly, demographic models suggest recent divergence (within the last 20,000 years) between subspecies and strong population bottlenecks. Amur tiger genomes revealed the strongest signals of selection related to metabolic adaptation to cold, whereas Sumatran tigers show evidence of weak selection for genes involved in body size regulation. We recommend detailed investigation of local adaptation in Amur and Sumatran tigers prior to initiating genetic rescue.  相似文献   

2.
Today, most wild tigers live in small, isolated Protected Areas within human dominated landscapes in the Indian subcontinent. Future survival of tigers depends on increasing local population size, as well as maintaining connectivity between populations. While significant conservation effort has been invested in increasing tiger population size, few initiatives have focused on landscape-level connectivity and on understanding the effect different landscape elements have on maintaining connectivity. We combined individual-based genetic and landscape ecology approaches to address this issue in six protected areas with varying tiger densities and separation in the Central Indian tiger landscape. We non-invasively sampled 55 tigers from different protected areas within this landscape. Maximum-likelihood and Bayesian genetic assignment tests indicate long-range tiger dispersal (on the order of 650 km) between protected areas. Further geo-spatial analyses revealed that tiger connectivity was affected by landscape elements such as human settlements, road density and host-population tiger density, but not by distance between populations. Our results elucidate the importance of landscape and habitat viability outside and between protected areas and provide a quantitative approach to test functionality of tiger corridors. We suggest future management strategies aim to minimize urban expansion between protected areas to maximize tiger connectivity. Achieving this goal in the context of ongoing urbanization and need to sustain current economic growth exerts enormous pressure on the remaining tiger habitats and emerges as a big challenge to conserve wild tigers in the Indian subcontinent.  相似文献   

3.
Over the past century, the endangered Amur tiger (Panthera tigris altaica) has experienced a severe contraction in demography and geographic range because of habitat loss, poaching, and prey depletion. In its historical home in Northeast China, there appears to be a single tiger population that includes tigers in Southwest Primorye and Northeast China; however, the current demographic status of this population is uncertain. Information on the abundance, distribution and genetic diversity of this population for assessing the efficacy of conservation interventions are scarce. We used noninvasive genetic detection data from scats, capture-recapture models and an accumulation curve method to estimate the abundance of Amur tigers in Northeast China. We identified 11 individual tigers (6 females and 5 males) using 10 microsatellite loci in three nature reserves between April 2013 and May 2015. These tigers are confined primarily to a Hunchun Nature Reserve along the border with Russia, with an estimated population abundance of 9–11 tigers during the winter of 2014–2015. They showed a low level of genetic diversity. The mean number of alleles per locus was 2.60 and expected and observed heterozygosity were 0.42 and 0.49, respectively. We also documented long-distance dispersal (~270 km) of a male Amur tiger to Huangnihe Nature Reserve from the border, suggesting that the expansion of neighboring Russian populations may eventually help sustain Chinese populations. However, the small and isolated population recorded by this study demonstrate that there is an urgent need for more intensive regional management to create a tiger-permeable landscape and increased genetic connectivity with other populations.  相似文献   

4.
The Sundarbans tiger inhabits a unique mangrove habitat and are morphologically distinct from the recognized tiger subspecies in terms of skull morphometrics and body size. Thus, there is an urgent need to assess their ecological and genetic distinctiveness and determine if Sundarbans tigers should be defined and managed as separate conservation unit. We utilized nine microsatellites and 3 kb from four mitochondrial DNA (mtDNA) genes to estimate genetic variability, population structure, demographic parameters and visualize historic and contemporary connectivity among tiger populations from Sundarbans and mainland India. We also evaluated the traits that determine exchangeability or adaptive differences among tiger populations. Data from both markers suggest that Sundarbans tiger is not a separate tiger subspecies and should be regarded as Bengal tiger (P. t. tigris) subspecies. Maximum likelihood phylogenetic analyses of the mtDNA data revealed reciprocal monophyly. Genetic differentiation was found stronger for mtDNA than nuclear DNA. Microsatellite markers indicated low genetic variation in Sundarbans tigers (He= 0.58) as compared to other mainland populations, such as northern and Peninsular (Hebetween 0.67- 0.70). Molecular data supports migration between mainland and Sundarbans populations until very recent times. We attribute this reduction in gene flow to accelerated fragmentation and habitat alteration in the landscape over the past few centuries. Demographic analyses suggest that Sundarbans tigers have diverged recently from peninsular tiger population within last 2000 years. Sundarbans tigers are the most divergent group of Bengal tigers, and ecologically non-exchangeable with other tiger populations, and thus should be managed as a separate “evolutionarily significant unit” (ESU) following the adaptive evolutionary conservation (AEC) concept.  相似文献   

5.
A Harihar  B Pandav 《PloS one》2012,7(7):e40105
Occupying only 7% of their historical range and confined to forested habitats interspersed in a matrix of human dominated landscapes, tigers (Panthera tigris) typify the problems faced by most large carnivores worldwide. With heads of governments of tiger range countries pledging to reverse the extinction process and setting a goal of doubling wild tiger numbers by 2022, achieving this target would require identifying existing breeding cores, potential breeding habitats and opportunities for dispersal. The Terai Arc Landscape (TAL) represents one region which has recently witnessed recovery of tiger populations following conservation efforts. In this study, we develop a spatially explicit tiger occupancy model with survey data from 2009–10 based on a priori knowledge of tiger biology and specific issues plaguing the western TAL (6,979 km2), which occurs in two disjunct units (Tiger Habitat Blocks; THBs). Although the overall occupancy of tigers was 0.588 (SE 0.071), our results clearly indicate that loss in functionality of a regional corridor has resulted in tigers now occupying 17.58% of the available habitat in THB I in comparison to 88.5% in THB II. The current patterns of occupancy were best explained by models incorporating the interactive effect of habitat blocks (AIC w = 0.883) on wild prey availability (AIC w = 0.742) and anthropogenic disturbances (AIC w = 0.143). Our analysis has helped identify areas of high tiger occupancy both within and outside existing protected areas, which highlights the need for a unified control of the landscape under a single conservation unit with the primary focus of managing tigers and associated wildlife. Finally, in the light of global conservation targets and recent legislations in India, our study assumes significance as we identify opportunities to secure (e.g. THB II) and increase (e.g. THB I) tiger populations in the landscape.  相似文献   

6.
Tigers are endangered apex predators. They typify endangered species because they are elusive, rare, and face numerous threats across their range. Tigers also symbolize conservation. However, it is very difficult to study tigers because of their stated nature. Also, tiger conservation is a geopolitically sensitive topic, making it difficult to use the studies to propose evidence-based management that allows their recovery, especially in the context of conservation genetics. Zhang et al. (Mol. Ecol. Resour., 2022) have created very valuable and rare resources to aid the community in conserving tigers. First, they present chromosome level genome assemblies of a South China tiger and an Amur tiger. Second, they present whole genome sequences of 16 captive South China tigers. Additionally, by using the assemblies they model the demographic history of these populations, estimate inbreeding and the potential threats they face in captivity. This approach is particularly important because genetic management is now the only remaining option for South China tigers, because they are extinct in the wild. In other words, captive individuals are our only hope for some day restoring the wild populations of South China tigers.  相似文献   

7.
Even with global support for tiger (Panthera tigris) conservation their survival is threatened by poaching, habitat loss and isolation. Currently about 3,000 wild tigers persist in small fragmented populations within seven percent of their historic range. Identifying and securing habitat linkages that connect source populations for maintaining landscape-level gene flow is an important long-term conservation strategy for endangered carnivores. However, habitat corridors that link regional tiger populations are often lost to development projects due to lack of objective evidence on their importance. Here, we use individual based genetic analysis in combination with landscape permeability models to identify and prioritize movement corridors across seven tiger populations within the Central Indian Landscape. By using a panel of 11 microsatellites we identified 169 individual tigers from 587 scat and 17 tissue samples. We detected four genetic clusters within Central India with limited gene flow among three of them. Bayesian and likelihood analyses identified 17 tigers as having recent immigrant ancestry. Spatially explicit tiger occupancy obtained from extensive landscape-scale surveys across 76,913 km2 of forest habitat was found to be only 21,290 km2. After accounting for detection bias, the covariates that best explained tiger occupancy were large, remote, dense forest patches; large ungulate abundance, and low human footprint. We used tiger occupancy probability to parameterize habitat permeability for modeling habitat linkages using least-cost and circuit theory pathway analyses. Pairwise genetic differences (F ST) between populations were better explained by modeled linkage costs (r>0.5, p<0.05) compared to Euclidean distances, which was in consonance with observed habitat fragmentation. The results of our study highlight that many corridors may still be functional as there is evidence of contemporary migration. Conservation efforts should provide legal status to corridors, use smart green infrastructure to mitigate development impacts, and restore habitats where connectivity has been lost.  相似文献   

8.
Understanding the patterns of gene flow of an endangered species metapopulation occupying a fragmented habitat is crucial for landscape-level conservation planning and devising effective conservation strategies. Tigers (Panthera tigris) are globally endangered and their populations are highly fragmented and exist in a few isolated metapopulations across their range. We used multi-locus genotypic data from 273 individual tigers (Panthera tigris tigris) from four tiger populations of the Satpura–Maikal landscape of central India to determine whether the corridors in this landscape are functional. This 45 000 km2 landscape contains 17% of India''s tiger population and 12% of its tiger habitat. We applied Bayesian and coalescent-based analyses to estimate contemporary and historical gene flow among these populations and to infer their evolutionary history. We found that the tiger metapopulation in central India has high rates of historical and contemporary gene flow. The tests for population history reveal that tigers populated central India about 10 000 years ago. Their population subdivision began about 1000 years ago and accelerated about 200 years ago owing to habitat fragmentation, leading to four spatially separated populations. These four populations have been in migration–drift equilibrium maintained by high gene flow. We found the highest rates of contemporary gene flow in populations that are connected by forest corridors. This information is highly relevant to conservation practitioners and policy makers, because deforestation, road widening and mining are imminent threats to these corridors.  相似文献   

9.

Background

Tiger populations are dwindling rapidly making it increasingly difficult to study their dispersal and mating behaviour in the wild, more so tiger being a secretive and solitary carnivore.

Methods

We used non-invasively obtained genetic data to establish the presence of 28 tigers, 22 females and 6 males, within the core area of Pench tiger reserve, Madhya Pradesh. This data was evaluated along with spatial autocorrelation and relatedness analyses to understand patterns of dispersal and philopatry in tigers within this well-managed and healthy tiger habitat in India.

Results

We established male-biased dispersal and female philopatry in tigers and reiterated this finding with multiple analyses. Females show positive correlation up to 7 kms (which corresponds to an area of approximately 160 km2) however this correlation is significantly positive only upto 4 kms, or 50 km2 (r  = 0.129, p<0.0125). Males do not exhibit any significant correlation in any of the distance classes within the forest (upto 300 km2). We also show evidence of female dispersal upto 26 kms in this landscape.

Conclusions

Animal movements are important for fitness, reproductive success, genetic diversity and gene exchange among populations. In light of the current endangered status of tigers in the world, this study will help us understand tiger behavior and movement. Our findings also have important implications for better management of habitats and interconnecting corridors to save this charismatic species.  相似文献   

10.
虎(Panthera tigris)作为顶级捕食者, 对维持森林生态系统服务和结构完整性有着重要作用, 是研究和保护工作的旗舰物种。历史上, 虎曾广泛分布于亚洲大部分地区, 如今仅分布于南亚、东南亚和东北亚的破碎化栖息地, 各区域种群处于濒危或极度濒危状态。准确了解野生虎的种群状态和生态需求信息对于科学开展保护和恢复工作至关重要。本文通过综述近几十年的研究文献, 总结了野生虎种群现状和主要威胁因素, 评价了已有研究的重点与不足, 为未来亚洲虎种群的研究和保护提出了建议。目前与虎相关的研究主要集中在分布范围最广的孟加拉虎(P. t. tigris)和东北虎(P. t. altaica) 2个亚种, 而最急需关注的其他亚种仍研究不足。经过近十几年的努力和保护投入, 目前野生虎种群数量已从2010年的大约3,200只恢复到现在约4,500只, 但在越南、柬埔寨和老挝3个国家已经灭绝。虎面临的主要威胁包括持续的栖息地破坏和隔离、猎物缺乏、近交衰退、人虎冲突、贸易与盗猎和疾病威胁等。未来的研究和保护工作需要加强种群和栖息地连通性恢复、个体重引入、疾病管控以及加强跨境合作和反盗猎等。  相似文献   

11.
The implementation of Project Tiger in India, 1973–1974, was justly hailed as a triumph of international environmental advocacy. It occurred as a growing number of conservation-oriented biologists were beginning to argue forcefully for scientifically managed conservation of species and ecosystems – the same scientists who would, by the mid-1980s, call themselves conservation biologists. Although India accepted international funds to implement Project Tiger, it strictly limited research posts to Government of India Foresters, against the protests of Indian and US biologists who hoped to conduct the scientific studies that would lead to better management and thus more effective conservation of the tiger. The foresters were not trained to conduct research, and in fact did not produce any of significance for the first 15 years of Project Tiger’s existence. The failure of biologists to gain access to India’s tigers in the 1970s was caused by many factors, but not least among them was a history of disdain among conservation-oriented biologists for government officials managing reserves, and the local politics of conservation. Project Tiger, then, serves as a case study for the discussion of the intersection of conservation biology with non-scientific concerns, including nationalism and the desire of the Indian government to more completely control its land.1I would like to thank the participants in the 2003 Southwest Colloquium for the Life Sciences for their constructive comments on an earlier version of this paper, as well as the two unusually helpful (anonymous) reviewers.  相似文献   

12.
华南虎是世界上密切关注的旗舰物种,在过去的10 年间没有发现野生华南虎存在的证据,因此它是极度濒危的虎亚种。福建梅花山圈养华南虎群体是整个圈养华南虎群体的重要组成部分,拥有 12 只华南虎。基于组合长度为 3934 bp 的线粒体序列分析发现梅花山圈养华南虎拥有 3 种线粒体单倍型; 而基于 20 个微卫星位点基因型分析显示梅花山圈养华南虎一共有71 个等位基因,平均等位基因数是3. 55,等位基因丰度的平均值是3. 32,平均期望杂合度和多态信息含量( PIC) 分别为0. 513 和0. 445。这些提示梅花山华南虎圈养群体维持着较高的遗传多样性。  相似文献   

13.
Evidence is vital. Understanding what interventions are effective is critical for the conservation of wild tigers and conservation biology in general. We evaluated the effectiveness of tiger reserves within India, a country with more than half of the estimated wild tiger population, with comparative effectiveness research. Other complex environments, medicine and business use these techniques where cause and effects are often non-linear. These techniques also allowed us to evaluate data from the small sample size often seen in conservation interventions. The opinions of three tiger experts were used to generate a list of seven tiger reserves classified as successful and five reserves as failures. We also used expert opinion to identify any key individuals that garnered widespread support for tiger conservation at any of the identified reserves. Using data from the Indian Census, World Database on Protected Areas, and the Socioeconomic Data and Applications Center, we analyzed the human population around the tiger reserves. We found two surprising insights that have received scant attention in the peer-reviewed literature. First, one can achieve tiger conservation success even within a densely populated human landscape where a high percentage of the population is involved in agriculture. Second, the presence of “conservation champions” can dramatically affect the performance of individual reserves and have positive outcomes for tiger conservation.  相似文献   

14.
Bengal tigers are highly endangered and knowledge on adaptive genetic variation can be essential for efficient conservation and management. Here we present the first assessment of allelic variation in major histocompatibility complex (MHC) class I and MHC class II DRB genes for wild and captive tigers from India. We amplified, cloned, and sequenced alpha-1 and alpha-2 domain of MHC class I and beta-1 domain of MHC class II DRB genes in 16 tiger specimens of different geographic origin. We detected high variability in peptide-binding sites, presumably resulting from positive selection. Tigers exhibit a low number of MHC DRB alleles, similar to other endangered big cats. Our initial assessment—admittedly with limited geographic coverage and sample size—did not reveal significant differences between captive and wild tigers with regard to MHC variability. In addition, we successfully amplified MHC DRB alleles from scat samples. Our characterization of tiger MHC alleles forms a basis for further in-depth analyses of MHC variability in this illustrative threatened mammal.  相似文献   

15.

Background

Bengal tiger Panthera tigris tigris the National Animal of India, is an endangered species. Estimating populations for such species is the main objective for designing conservation measures and for evaluating those that are already in place. Due to the tiger's cryptic and secretive behaviour, it is not possible to enumerate and monitor its populations through direct observations; instead indirect methods have always been used for studying tigers in the wild. DNA methods based on non-invasive sampling have not been attempted so far for tiger population studies in India. We describe here a pilot study using DNA extracted from faecal samples of tigers for the purpose of population estimation.

Results

In this study, PCR primers were developed based on tiger-specific variations in the mitochondrial cytochrome b for reliably identifying tiger faecal samples from those of sympatric carnivores. Microsatellite markers were developed for the identification of individual tigers with a sibling Probability of Identity of 0.005 that can distinguish even closely related individuals with 99.9% certainty. The effectiveness of using field-collected tiger faecal samples for DNA analysis was evaluated by sampling, identification and subsequently genotyping samples from two protected areas in southern India.

Conclusion

Our results demonstrate the feasibility of using tiger faecal matter as a potential source of DNA for population estimation of tigers in protected areas in India in addition to the methods currently in use.
  相似文献   

16.
Global tiger Panthera tigris populations mostly survive within the geographically fragmented forest patches, thereby limited genetic exchange between isolated populations. Assessing the genetic status of these populations can reveal the effects of dispersal barriers and provide critical insights to guide future conservation actions. Using non-invasively collected biological samples, we investigated fine-scale genetic structure of tigers in the Sundarbans mangrove forests intersected by the complex river systems, and which holds one of the largest global tiger populations. We genotyped 52 tiger samples at 10 polymorphic microsatellite loci, and sequenced 33 of them for a total of 1263 base-pairs at four mitochondrial gene fragments. Microsatellite analyses exhibit a signature of fine-scale genetic structure, which might have been the consequence of limited tiger dispersal due to wide rivers across the Sundarbans. Similarly, mitochondrial data show a historic pattern of population isolation that might be due to wider rivers across the entire Sundarbans shared by Bangladesh and India. Given the intrinsic nature of the mangrove habitat embedded with numerous rivers, increased commercial traffic and human activities may further impede tiger dispersal across wide rivers, escalating further genetic isolation of the Sundarbans tigers.  相似文献   

17.
The great Indian bustard (Ardeotis nigriceps) is an endemic endangered bird of the Indian subcontinent with a declining population, as a result of hunting and continuing habitat loss. In this first genetic study of this little-known species, we investigate the diversity of the mitochondrial DNA (hypervariable control region II and cytochrome b gene) among samples (n = 63) from five states within the current distribution range of great Indian bustards in India. We find just three haplotypes defined by three variable sites, a comparatively low genetic diversity of π = 0.0021 ± 0.0012 for cytochrome b, 0.0008 ± 0.0007 for the control region (CR), and 0.0017 ± 0.0069 for combined regions and no phylogeographic structure between populations. We provide evidence for a bottleneck event, estimate an effective population size (Ne) that is roughly concordant with recent population size estimates based on field surveys (~200 to 400), but extremely low for a widely distributed species. We also discuss the conservation implications. Based on our findings, we strongly recommend upgrading the IUCN threat status from Endangered to Critically Endangered.  相似文献   

18.
The Caspian tiger (Panthera tigris virgata) flourished in Central Asian riverine forest systems in a range disjunct from that of other tigers, but was driven to extinction in 1970 prior to a modern molecular evaluation. For over a century naturalists puzzled over the taxonomic validity, placement, and biogeographic origin of this enigmatic animal. Using ancient-DNA (aDNA) methodology, we generated composite mtDNA haplotypes from twenty wild Caspian tigers from throughout their historic range sampled from museum collections. We found that Caspian tigers carry a major mtDNA haplotype differing by only a single nucleotide from the monomorphic haplotype found across all contemporary Amur tigers (P. t. altaica). Phylogeographic analysis with extant tiger subspecies suggests that less than 10,000 years ago the Caspian/Amur tiger ancestor colonized Central Asia via the Gansu Corridor (Silk Road) from eastern China then subsequently traversed Siberia eastward to establish the Amur tiger in the Russian Far East. The conservation implications of these findings are far reaching, as the observed genetic depletion characteristic of modern Amur tigers likely reflects these founder migrations and therefore predates human influence. Also, due to their evolutionary propinquity, living Amur tigers offer an appropriate genetic source should reintroductions to the former range of the Caspian tiger be implemented.  相似文献   

19.
The Amur tiger, Panthera tigris altaica, is a highly endangered felid whose range and population size has been severely reduced in recent times. At present, the wild population is estimated at 490 individuals, having rebounded from the 20–30 tigers remaining following a severe bottleneck in the 1940's. The current study presents preliminary data on the patterns and levels of genetic variation in the mitochondrial DNA control region using DNA extracted from non-invasively sampled faecal material, collected throughout the entire range of P. t. altaica in the Russian Far East. Analysis of 82 scat samples representing at least 27 individuals revealed extremely low levels of CR haplotype diversity, characterized by a single widespread haplotype (96.4%) and two rare variants, each differing by a single step within the hypervariable I (2.4%) and central conserved regions (1.2%), respectively. A comparison with previous data on cytochrome bvariation in 14 captive individuals revealed a potentially greater amount of genetic variation represented in captivity relative to that found in the wild population. The extremely low levels of mitochondrial DNA variation in the wild population is discussed in light of the demographic processes that might have shaped these patterns as well as the potential bias introduced through analysis of fecal samples. These results highlight the continuing need to assess levels of genetic variation even in recovering populations that are increasing in number and underscore the important role that captive breeding programs may play in preserving remnant genetic diversity of endangered species.  相似文献   

20.
Fostering local community tolerance for endangered carnivores, such as tigers (Panthera tigris), is a core component of many conservation strategies. Identification of antecedents of tolerance will facilitate the development of effective tolerance-building conservation action and secure local community support for, and involvement in, conservation initiatives. We use a stated preference approach for measuring tolerance, based on the ‘Wildlife Stakeholder Acceptance Capacity’ concept, to explore villagers’ tolerance levels for tigers in the Bangladesh Sundarbans, an area where, at the time of the research, human-tiger conflict was severe. We apply structural equation modeling to test an a priori defined theoretical model of tolerance and identify the experiential and psychological basis of tolerance in this community. Our results indicate that beliefs about tigers and about the perceived current tiger population trend are predictors of tolerance for tigers. Positive beliefs about tigers and a belief that the tiger population is not currently increasing are both associated with greater stated tolerance for the species. Contrary to commonly-held notions, negative experiences with tigers do not directly affect tolerance levels; instead, their effect is mediated by villagers’ beliefs about tigers and risk perceptions concerning human-tiger conflict incidents. These findings highlight a need to explore and understand the socio-psychological factors that encourage tolerance towards endangered species. Our research also demonstrates the applicability of this approach to tolerance research to a wide range of socio-economic and cultural contexts and reveals its capacity to enhance carnivore conservation efforts worldwide.  相似文献   

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