重要物种优先保护种群的确定

由于同一物种不同种群的重要性不同、用于物种保护的资金有限以及保护与发展经济之间的矛盾,因此对于重要物种（尤其是濒危种类以及农作物和驯化动物的野生近缘种）需要确定保护什么以及保护哪儿。目前确定优先保护种群的方法主要有3类,分别为基于遗传变异、基于遗传差异性和基于遗传贡献率的方法。基于遗传变异的方法主要是根据遗传变异程度（尤其是等位基因多样性）来确定优先保护的顺序,但忽略了种群之间的遗传差异性,这容易使得存在于遗传变异程度较低的种群中的特有等位基因得不到有效保护。而基于遗传差异性的方法（如确定进化显著单元）则是从遗传分化程度的角度考虑优先性,即独特性越强的种群越具有保护价值。基于遗传贡献率的方法由于综合考虑了遗传多样性和差异性,最适合于确定哪些种群需要优先保护。我国开展此类研究十分必要。     

分子标记在濒危物种保护中的应用

分子标记可揭示种群遗传和进化信息, 为制定濒危物种保护措施、指导恢复实践提供重要依据。本文主要介绍了分子标记在濒危物种保护过程不同环节中的应用, 包括: (1)正确识别保护单元, 如排除隐存种和杂交种的影响; (2)确定优先保护单元, 包括优先保护区域、优先保护物种、优先保护种群等; (3)指导迁地保护; (4)对保护工作的动态监测和评估。文章最后探讨了分子标记应用于保护的发展方向, 如开展长期的种群遗传组成监测、切实应用于保护管理实践、将基因组学等遗传信息用于全球变化背景下保护策略的制定等, 期望为分子标记技术在生物多样性保护的研究和实践中提供参考。     

七鳃鳗遗传多样性与演化研究进展

七鳃鳗(Petromyzonidae)是目前已知最古老的脊椎动物中惟一的幸存者.对其资源保护和演化发育生物学的研究正日益受到重视.本文从染色体、蛋白质和DNA水平总结近年来七鳃鳗遗传多样性与演化方面的研究进展.重点介绍了限制性酶切片段长度多态性、DNA随机扩增多态性、DNA扩增片段长度多态性、微卫星DNA标记等技术及线粒体DNA和功能基因研究应用于七鳃鳗种群遗传多样性、遗传分化、遗传结构、种质鉴定与渔业资源管理及系统进化等方面的新进展.     

贵州疣螈D-loop区和tRNAPhe序列变异及群体遗传多样性

贵州疣螈(Tylototriton kweichowensis)是我国特有的国家Ⅱ级保护动物,分布面积极为狭窄。为了解其遗传多样性现状,作者采获了几乎覆盖其分布范围的12群体的58个体的材料,测定了线粒体D-loop区(mtDNA控制区)及tRNAPhe基因全序列共808bp,发现16个变异位点,定义了26个单元型。遗传多样性检测显示,贵州疣螈种群具有高的单元型多样性和低的核苷酸多样性。Tajima’s D和Fuand Li’s D值检测结果均表明,贵州疣螈种群相对于中性进化的歧异度并没有明显的偏离。系统发育及网络进化分析没有显示出单元型和地理位置的对应关系,各群体的单元型都相互散布在不同的分布群中,呈现一种混杂的分布格局。水城群体与其他任一群体间基因流Nm1,有分化的迹象。总的来说,贵州疣螈各群体之间没有发生极显著的遗传分化,因此建议将贵州疣螈所有群体作为一个整体管理单元加以保护。     

分子遗传保护研究进展

介绍了遗传保护的内涵和遗传保护的途径及存在的问题,从遗传多样性检测、种群内遗传变异及进化分化的鉴别、就地或移地保护物种的繁殖与遗传保护、遗传结构地理差异、种群大小的遗传基础与保护等方面综述了遗传保护研究的进展。     

大熊猫野化放归中的遗传学分析

大熊猫为我国特有的濒危物种,由于人类活动的影响,其生境遭到破碎化以致孤立小种群间基因流受限制,严重威胁野生孤立小种群的续存。野化放归以复壮并建立能自我维持的野生种群是物种保护的一种有效措施,这在国内外已有成功先例。野化放归圈养大熊猫以复壮野生种群是大熊猫保护的重要策略之一。然而,破碎化生境阻碍了小种群间的基因交流,加剧了因近交和遗传漂变带来生存力下降的危机。因此大熊猫的放归必须首先考虑其遗传背景,以改善种群基因库为目的。综合微卫星与线粒体等分子标记分析显示,现存野生大熊猫种群和圈养种群仍具有中等或以上的遗传水平,具有较大的进化潜力,这为大熊猫野化放归提供了遗传学支持。另外,小相岭和大相岭种群的遗传水平最低,应首先考虑这些种群的复壮,并且对秦岭种群进行特殊管理与保护。大熊猫的野化放归应着重于野放个体亲缘度的合理选择、基因丰富度的优先选择和有害基因的反向选择等三个遗传因素。本文旨在综合分析大熊猫现存种群遗传现状及其在野化放归中的决策性,以期为大熊猫野化放归提供参考依据。     

两栖动物MHC基因研究进展

MHC是高度多态的基因群,广泛分布于各种脊椎动物体内。由于MHC基因的多态性,使其在脊椎动物的免疫、遗传、进化、保护等许多方面的研究倍受关注。本文综述了两栖类MHC基因自研究以来国内外有关该基因的研究报道,包括其结构、功能以及在两栖类遗传进化、种群遗传学、免疫遗传学及抗病中的应用,并对研究前景进行了展望。     

珠江源头入侵种波氏吻虾虎的遗传多样性分析

为了解入侵种波氏吻虾虎Rhinogobius cliffordpopei在珠江源头地区的遗传多样性分布特征及其影响成因,本研究以线粒体细胞色素b(cyt b)基因为分子标记,对珠江源头的9个水库自然种群进行了遗传多样性与遗传分化分析。获得该物种cyt b基因全序列1 141 bp,其中保守位点1 072个,变异位点69个,无插入和缺失位点。96只个体具有5个单倍型,群体单倍型多样性为0.359±0.059,核苷酸多样性为0.021±0.010,表现为低单倍型多样性与高核苷酸多样性的群体遗传特征。以外群子陵吻虾虎R.giurinus、褐吻虾虎R.brunneus和短吻红斑吻虾虎R.rubromaculatus构建的分子系统发育树和网络分支图显示,波氏吻虾虎群体的所有单倍型与外群物种分开,构成一个单系群,并分化为2个明显的系统分支。分子变异分析结果表明,种群间和种群内的遗传变异率分别为62.99%、37.01%,固定指数为0.630(P<0.01),证实波氏吻虾虎群体形成了显著的遗传分化结构。波氏吻虾虎在珠江源头入侵地具有较高的遗传多样性水平与显著的遗传结构,入侵种群可能受到了奠基者事件和遗传瓶颈效应的影响,而多次人为引入和水利大坝的隔离作用可能为该物种扩散分布和积累突变提供了条件。研究结果将为防治波氏吻虾虎的入侵危害及保护土著鱼类物种多样性提供科学指导。     

不仅仅是遗传多样性:植物保护遗传学进展

保护遗传学研究的是影响物种灭绝的遗传因素以及濒危物种的遗传管理, 以降低物种的灭绝风险。本文从遗传多样性本身及其对生态系统的影响两个方面介绍了植物保护遗传学的最新进展。根据遗传标记的功能, 保护遗传学研究可分为选择中性遗传变异研究和适应性遗传变异两个方面。对于目前主要采用的选择中性遗传标记研究, 本文着重介绍了以下方面的最新进展: (1)利用遗传标记进行个体、物种或遗传单元的鉴定, 从而有效地设计保护策略, 避免在迁地保护中混淆物种, 提高保护效率; (2)应重视由于物种自身生殖、扩散等原因造成的隐性瓶颈效应。由于选择中性遗传标记并不能准确反映物种的适应性遗传基础, 从适应性遗传变异角度研究濒危物种的进化潜力已成为保护遗传学的研究前沿。大部分相关研究还集中在利用基因组扫描检测受选择的位点, 而对功能基因的适应性研究还比较少。景观遗传学旨在解释景观和生境影响下的种群间基因流和遗传多样性格局, 这方面研究将会促进我们更多了解种群基因流的地理限制因子和不同景观基质下的种群遗传差异。遗传多样性作为物种的一种属性亦可在一定程度上反馈, 并影响生态系统。这提示我们不仅仅是濒危物种, 常见物种的遗传多样性及其保护亦很重要。最后, 我们从4个方面对保护遗传学研究进行了展望, 包括应加强将生态系统各环节联系起来研究遗传多样性, 在技术手段上利用多态性更丰富的分子标记, 同时强调了对常见物种保护遗传学研究的重要性, 并初步分析了我国保护遗传学研究与国际水平的差距, 建议加强种群遗传学和进化生物学基础理论的学习。     

优先保护种群的确定 II.单倍型丰富度模型及在银杏中的应用

由于不同种群遗传多样性的不均匀分布以及资金和人力资源等的限制 ,加上经济发展常与生物多样性保护存在矛盾 ,对于珍稀濒危物种等需要确定优先保护的种群。确定优先保护种群有 3种途径 :一是以种群遗传变异为依据 ,这一方法常用于指导种质资源收集 ;二是遗传差异为依据 ,如进化显著单元 ;三是以综合考虑种群内遗传变异和遗传差异的遗传贡献率为依据。前两种方法各自考虑了一个方面 ,存在一定缺陷 ,第 3种方法弥补了这种不足 ,但是目前缺少计算遗传贡献率的模型。采用等位基因丰富度参数 ,从种群内遗传变异、种群间遗传变异以及物种水平遗传变异之间的关系出发 ,提出了将种群间遗传变异分配到各种群的模型 ,以及计算各种群遗传贡献的方法。利用获得的 6个银杏种群 cp DNA PCR- RFL P单倍型数据对模型进行了说明 ,并根据计算结果得出金佛山、妥乐种群位于需要优先保护前列的初步结果     

Recent Evolutionary History of Tigers Highlights Contrasting Roles of Genetic Drift and Selection

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.     

Phylogeographical population structure of tiger quolls Dasyurus maculatus (Dasyuridae: Marsupialia), an endangered carnivorous marsupial

Tiger quolls, Dasyurus maculatus, are the largest carnivorous marsupials still extant on the mainland of Australia, and occupy an important ecological niche as top predators and scavengers. Two allopatric subspecies are recognized, D.m. gracilis in north Queensland, and D.m. maculatus in the southeast of the mainland and Tasmania. D.m. gracilis is considered endangered while D.m. maculatus is listed as vulnerable to extinction; both subspecies are still in decline. Phylogeographical subdivision was examined to determine evolutionarily significant units (ESUs) and management units (MUs) among populations of tiger quolls to assist in the conservation of these taxa. Ninety-three tiger quolls from nine representative populations were sampled from throughout the species range. Six nuclear microsatellite loci and the mitochondrial DNA (mtDNA) control region (471 bp) were used to examine ESUs and MUs in this species. We demonstrated that Tasmanian tiger quolls are reciprocally monophyletic to those from the mainland using mtDNA analysis, but D.m. gracilis was not monophyletic with respect to mainland D.m. maculatus. Analysis of microsatellite loci also revealed significant differences between the Tasmanian and mainland tiger quolls, and between D.m. gracilis and mainland D.m. maculatus. These results indicate that Tasmanian and mainland tiger quolls form two distinct evolutionary units but that D.m. gracilis and mainland D.m. maculatus are different MUs within the same ESU. The two marker types used in this study revealed different male and female dispersal patterns and indicate that the most appropriate units for short-term management are local populations. A revised classification and management plan are needed for tiger quolls, particularly in relation to conservation of the Tasmanian and Queensland populations.     

Tigers of Sundarbans in India: Is the Population a Separate Conservation Unit?

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.     

When the shoe doesn’t fit: applying conservation unit concepts to western painted turtles at their northern periphery

As biodiversity continues to be lost at an alarming rate, strategies for prioritizing populations for conservation have become increasingly important. Maintaining intraspecific genetic diversity is of particular importance for preserving evolutionary history and the potential for future adaptation. In order to effectively protect this diversity, units below the species level need to be defined. However, delineation of such units is subject to many challenges, with no one strategy applying universally across taxa. In this study we carried out the first genetic assessment of the western painted turtle (Chrysemys picta bellii) at its northern periphery in British Columbia (BC), Canada, using mitochondrial DNA haplotypic and microsatellite genotypic data to examine population structure and demographic history. We compared the application of evolutionarily significant unit and management unit criteria with Canadian designatable unit guidelines to determine appropriate conservation units. Our results show that BC western painted turtles form a single evolutionarily significant unit, with each occupied site constituting a separate management unit. In contrast, there is evidence for six discrete designatable units. Patterns of genetic variation in BC western painted turtles indicate that the conservation of each region is important to maintaining regional diversity and evolutionary novelty in this widespread species.     

The role of subspecies in obscuring avian biological diversity and misleading conservation policy

Subspecies are often used in ways that require their evolutionary independence, for example as proxies for units of conservation. Mitochondrial DNA sequence data reveal that 97% of continentally distributed avian subspecies lack the population genetic structure indicative of a distinct evolutionary unit. Subspecies considered threatened or endangered, some of which have been targets of expensive restoration efforts, also generally lack genetic distinctiveness. Although sequence data show that species include 1.9 historically significant units on average, these units are not reflected by current subspecies nomenclature. Yet, it is these unnamed units and not named subspecies that should play a major role in guiding conservation efforts and in identifying biological diversity. Thus, a massive reorganization of classifications is required so that the lowest ranks, be they species or subspecies, reflect evolutionary diversity. Until such reorganization is accomplished, the subspecies rank will continue to hinder progress in taxonomy, evolutionary studies and especially conservation.     

Phylogeography and genetic ancestry of tigers (Panthera tigris)

Eight traditional subspecies of tiger (Panthera tigris),of which three recently became extinct, are commonly recognized on the basis of geographic isolation and morphological characteristics. To investigate the species' evolutionary history and to establish objective methods for subspecies recognition, voucher specimens of blood, skin, hair, and/or skin biopsies from 134 tigers with verified geographic origins or heritage across the whole distribution range were examined for three molecular markers: (1) 4.0 kb of mitochondrial DNA (mtDNA) sequence; (2) allele variation in the nuclear major histocompatibility complex class II DRB gene; and (3) composite nuclear microsatellite genotypes based on 30 loci. Relatively low genetic variation with mtDNA,DRB,and microsatellite loci was found, but significant population subdivision was nonetheless apparent among five living subspecies. In addition, a distinct partition of the Indochinese subspecies P. t. corbetti in to northern Indochinese and Malayan Peninsula populations was discovered. Population genetic structure would suggest recognition of six taxonomic units or subspecies: (1) Amur tiger P. t. altaica; (2) northern Indochinese tiger P. t. corbetti; (3) South China tiger P. t. amoyensis; (4) Malayan tiger P. t. jacksoni, named for the tiger conservationist Peter Jackson; (5) Sumatran tiger P. t. sumatrae; and (6) Bengal tiger P. t. tigris. The proposed South China tiger lineage is tentative due to limited sampling. The age of the most recent common ancestor for tiger mtDNA was estimated to be 72,000-108,000 y, relatively younger than some other Panthera species. A combination of population expansions, reduced gene flow, and genetic drift following the last genetic diminution, and the recent anthropogenic range contraction, have led to the distinct genetic partitions. These results provide an explicit basis for subspecies recognition and will lead to the improved management and conservation of these recently isolated but distinct geographic populations of tigers.     

Forest corridors maintain historical gene flow in a tiger metapopulation in the highlands of central India

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.     

What determines attitude of local people towards tiger and leopard in Nepal?

Understanding attitude of local people towards big cats is vital for conservation interventions to succeed. Taking tigers and leopards as focal species, we investigated local peoples' attitude towards four subjects—tiger, tiger conservation, leopard, and leopard conservation—considering demographic and socio-economic factors as well as past experience with such predators in Nepal's first national park and a world heritage site, Chitwan National Park. The data were collected from 414 local people using structured questionnaires and their attitude towards the four subjects determined. We performed ordinal logistic regression analysis to identify the best fitted model and significant variables affecting attitudes. While majority of the people (51%) strongly liked tigers, fewer people (38%) had similar view while it came to leopard. However, a greater proportion of people strongly agreed that the conservation of tigers (61%) and leopards (53%) is important. About 12% people had negative attitude towards both big cats. We found women and low income respondents to likely have negative attitudes and higher caste Hindus to have positive attitudes towards both big cats and their conservation. Better educated persons and the owners to larger herds of livestock only agreed on conservation of tiger but not leopard. Past experience with the predator negatively affected attitude towards tiger but not leopard. We suggest the identified cohort of people with negative attitudes be more targeted in conservation initiatives. The reasons behind the similarities and differences in peoples’ attitudes are discussed and designation of species-specific programmes for both cats is recommended.     

Anti-bat tiger moth sounds: Form and function

The night sky is the venue of an ancient acoustic battle between echolocating bats and their insect prey. Many tiger moths (Lepidoptera: Arctiidae) answer the attack calls of bats with a barrage of high frequency clicks. Some moth species use these clicks for acoustic aposematism and mimicry, and others for sonar jamming, however, most of the work on these defensive functions has been done on individual moth species. We here analyze the diversity of structure in tiger moth sounds from 26 spe-cies collected at three locations in North and South America. A principal components analysis of the anti-bat tiger moth sounds reveals that they vary markedly along three axes: (1) frequency, (2) duty cycle (sound production per unit time) and frequency modulation, and (3) modulation cycle (clicks produced during flexion and relaxation of the sound producing tymbal) structure. Tiger moth species appear to cluster into two distinct groups: one with low duty cycle and few clicks per modulation cycle that supports an acoustic aposematism function, and a second with high duty cycle and many clicks per modulation cycle that is con-sistent with a sonar jamming function. This is the first evidence from a community-level analysis to support multiple functions for tiger moth sounds. We also provide evidence supporting an evolutionary history for the development of these strategies. Further-more, cross-correlation and spectrogram correlation measurements failed to support a "phantom echo" mechanism underlying sonar jamming, and instead point towards echo interference.