refugia

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  • 文章类型: Journal Article
    了解农业景观中嵌入的土地利用类型如何支持森林生物多样性至关重要,特别是在自然生态系统持续分裂和栖息地丧失的时期。这里,我们探索了奥罗米亚西部农业生态系统中土地利用类型的植物区系物种组成,埃塞俄比亚。为此,采用系统抽样方法,从122个主象限和610个亚象限中收集植物区系数据,以下以1500米间隔布置的横断面。主要的四人组以800米的间隔排列在横断面上,以评估木本物种,和五个子四边形(即,四个在角落,一个在中心)在每个主要地块内进行评估草本植物。因此,根据确定的五种土地利用类型对植物区系进行了评估,包括耕地,森林,放牧的土地,家庭花园,和河流。我们使用单向方差分析来测试土地利用类型之间物种多样性的差异。Adonis2和indval函数用于描述与土地利用类型有关的物种组成和指示物种。此外,NMDS用于可视化物种组成与排序空间中环境变量的关联。总共记录了285种植物,属于220属和89科。我们的结果表明物种多样性存在显著差异,物种组成不同,和土地利用类型之间的物种指标值。这些结果表明,土地利用类型在支持植物多样性方面的潜力是显著不同的;例如,与其他土地利用类型相比,放牧地和家庭花园的物种多样性和丰度更高。总的来说,我们的发现表明,农业景观的保护策略在规划时应考虑到土地利用类型之间支持生物多样性的能力差异。
    Understanding how land use types embedded in agricultural landscapes support forest biodiversity is critical, especially during this period of continuing fragmentation and habitat losses in natural ecosystems. Here, we explored the floristic species composition with respect to land use types in the agroecosystem of west Oromia, Ethiopia. For this, a systematic sampling method was employed to collect floristic data from 122 main quadrats and 610 sub-quadrats, following transects laid out with a 1500-m interval. The main quadrats were arranged on transects with an 800-m interval to assess woody species, and five sub-quadrats (i.e., four at the corners and one at the center) were taken within each main plot to assess herbaceous plants. Accordingly, the floristics were assessed with respect to the identified five land use types, including crop land, forest, grazing land, home gardens, and riverine. We used a one-way ANOVA to test the difference in species diversity among the land use types. Adonis 2 and indval functions were used to describe the species composition and indicator species in relation to the land use types. Moreover, NMDS was applied to visualize the associations of the species composition with environmental variables in ordination space. A total of 285 plant species belonging to 220 genera and 89 families were recorded. Our results showed significant differences in species diversity, dissimilarity in species composition, and species indicator values among the land use types. These results indicate that the potentiality of the land use types in supporting plant diversity is significantly different; for example, species diversity and abundances were higher in grazing lands and home gardens when compared with other land use types. Overall, our findings suggest that conservation strategies in agricultural landscapes should take into account the differences in capacity for supporting biodiversity among land use types when planning.
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  • 文章类型: Journal Article
    解开气候振荡和地理事件如何显着影响植物的遗传结构和人口统计学历史是植物地理学的中心主题。落叶古树种榆树主要分布在中国北方,具有木材和园艺价值。在目前的研究中,我们使用叶绿体DNA和生态生态位模型研究了大猩猩的系统发育结构和人口统计学历史。结果表明,群体遗传分化系数(NST)值显著大于单倍型频率(GST)值(p<0.05),这表明大叶菜具有明确的系统地理结构。系统发育推断表明,假定的叶绿体单倍型可分为三组,其中Ⅰ组被认为是祖先。尽管这些群体之间存在显著的遗传差异,基因流检测。所有单倍型的共同祖先都被推断为起源于中-晚期的新世,其次是第四纪发生的单倍型压倒性多样化。结合人口学模式和生态位建模,我们推测,山西和内蒙古周边地区在中国北方的冰期是大红的潜在避难所。我们的研究结果阐明了大叶树种的人口学格局,为进一步研究中国北方分布的珍贵树种提供了线索和参考。
    Disentangling how climate oscillations and geographical events significantly influence plants\' genetic architecture and demographic history is a central topic in phytogeography. The deciduous ancient tree species Ulmus macrocarpa is primarily distributed throughout Northern China and has timber and horticultural value. In the current study, we studied the phylogenic architecture and demographical history of U. macrocarpa using chloroplast DNA with ecological niche modeling. The results indicated that the populations\' genetic differentiation coefficient (NST) value was significantly greater than the haplotype frequency (GST) (p < 0.05), suggesting that U. macrocarpa had a clear phylogeographical structure. Phylogenetic inference showed that the putative chloroplast haplotypes could be divided into three groups, in which the group Ⅰ was considered to be ancestral. Despite significant genetic differentiation among these groups, gene flow was detected. The common ancestor of all haplotypes was inferred to originate in the middle-late Miocene, followed by the haplotype overwhelming diversification that occurred in the Quaternary. Combined with demography pattern and ecological niche modeling, we speculated that the surrounding areas of Shanxi and Inner Mongolia were potential refugia for U. macrocarpa during the glacial period in Northern China. Our results illuminated the demography pattern of U. macrocarpa and provided clues and references for further population genetics investigations of precious tree species distributed in Northern China.
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  • 文章类型: Journal Article
    更新世气候振荡对中国东部恒河猴(Macacamulatta)的遗传结构和人口统计学产生了重大影响。然而,中国亚热带和温带恒河猴的进化历史仍不清楚和/或存在争议。在这里,我们分析了常染色体,线粒体基因组,来自中国恒河猴84个个体的Y染色体。结果表明:(1)所有个体均分为泛西方和泛东方遗传组,其中显示陕西省是中国恒河猴西部扩散路线的最北端地区;(2)在中国亚热带和温带,恒河猴分为四个谱系(TH,DB,HS,和QL),它们的发散时间对应于倒数第二个冰川(300-130kya)和最后一个冰川(70-10kya),分别;(3)山的个体。太行山(TH)与山的个体密切相关。常染色体树中的大巴山(DB),而不是来自Mt的个人。如有丝分裂基因组树所示的黄山(HS),这支持了祖先恒河猴辐射到Mt中的假设。太行山。黄山经Mt.大巴山;(4)四个血统的人口统计学情景表明,恒河猴祖先的瓶颈和扩张与适当的栖息地减少和扩张相对应,这证实了他们经历了从Mt.黄山地区经华北平原至中国最北端与更新世冰川周期。这项研究为了解更新世冰川如何影响亚热带和温带中国的动物区系多样性提供了新的见解。特别是对于那些表现出不同的性别传播模式的人。
    Pleistocene climatic oscillations exerted significant influences on the genetic structure and demography of rhesus macaque (Macaca mulatta) in eastern China. However, the evolutionary history of rhesus macaques in subtropical and temperate China remained unclear and/or controversial. Herein, we analyzed the autosomes, mitochondrial genomes, and Y-chromosomes from 84 individuals of Chinese rhesus macaque. The results revealed that (1) all individuals were clustered into pan-west and pan-east genetic groups, which exhibited Shaanxi Province as the northernmost region of western dispersal route of rhesus macaques in China; (2) in subtropical and temperate China, rhesus macaques were divided into four lineages (TH, DB, HS, and QL), and their divergence times corresponded to the Penultimate Glaciation (300-130 kya) and Last Glaciation (70-10 kya), respectively; (3) the individuals from Mt. Taihangshan (TH) are closely related to individuals from Mt. Dabashan (DB) in the autosomal tree, rather than individuals from Mt. Huangshan (HS) as indicated by the mitogenome tree, which supports the hypothesis that the ancestral rhesus macaques radiated into Mt. Taihangshan from Mt. Huangshan via Mt. Dabashan; and (4) the demographic scenario of the four lineages showed the ancestral rhesus macaques bottleneck and expansion corresponding to the suitable habitat reduction and expansion, which confirmed they had experienced northward recolonization and southward retreat events from Mt. Huangshan area via Northern China Plain to Northernmost China along with Pleistocene glacial cycles. This study provides a new insight into understanding how Pleistocene glaciation has influenced faunal diversity in subtropical and temperate China, especially for those exhibiting differential patterns of sex dispersal.
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  • 文章类型: Journal Article
    受气候和景观特征急剧变化的影响,广泛分布的物种为研究环境对其进化和当前遗传多样性的影响提供了合适的模型。骰子蛇Natrixtessellata,广泛分布在西部古北地区就是这样一种物种。我们的目标是解决奈瑟拉的详细系统地理学,重点是具有4个线粒体谱系的中亚进化枝和具有3个线粒体谱系的安纳托利亚进化枝,追踪它们的起源,并关联影响它们随时间分布的环境变化。两个分支的预期发散时间始于上新世的3.7Mya,大约一百万年后达到谱系分化。两个分支的遗传多样性都很丰富,暗示不同的祖先地区,冰川避难所,人口变化,和殖民路线。里海血统是中亚最广泛的血统,分布在里海周围,到达阿富汗兴都库什山脉的山麓,和东欧西部的低地。它的分布受到沙漠的限制,山,和寒冷的草原环境。同样,哈萨克斯坦和乌兹别克斯坦的血统跟随中亚的阿姆河和SyrDarya水系统,范围由Kyzylkum和Karakum沙漠划定。在西边,安纳托利亚进化枝内有几个血统汇聚在半岛中部,其中2个是西亚特有的。这两个主要分支的分布受到里海周围和中亚山谷中更新世冰川避难所的扩展以及环境变化的影响,主要是通过干旱。
    Influenced by rapid changes in climate and landscape features since the Miocene, widely distributed species provide suitable models to study the environmental impact on their evolution and current genetic diversity. The dice snake Natrix tessellata, widely distributed in the Western Palearctic is one such species. We aimed to resolve a detailed phylogeography of N. tessellata with a focus on the Central Asian clade with 4 and the Anatolia clade with 3 mitochondrial lineages, trace their origin, and correlate the environmental changes that affected their distribution through time. The expected time of divergence of both clades began at 3.7 Mya in the Pliocene, reaching lineage differentiation approximately 1 million years later. The genetic diversity in both clades is rich, suggesting different ancestral areas, glacial refugia, demographic changes, and colonization routes. The Caspian lineage is the most widespread lineage in Central Asia, distributed around the Caspian Sea and reaching the foothills of the Hindu Kush Mountains in Afghanistan, and Eastern European lowlands in the west. Its distribution is limited by deserts, mountains, and cold steppe environments. Similarly, Kazakhstan and Uzbekistan lineages followed the Amu Darya and the Syr Darya water systems in Central Asia, with ranges delimited by the large Kyzylkum and Karakum deserts. On the western side, there are several lineages within the Anatolia clade that converged in the central part of the peninsula with 2 being endemic to Western Asia. The distribution of both main clades was affected by expansion from their Pleistocene glacial refugia around the Caspian Sea and in the valleys of Central Asia as well as by environmental changes, mostly through aridification.
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  • 文章类型: Journal Article
    北极物种的遗传变异通常受到更新世期间的代际影响,由于冰盖使景观支离破碎,流离失所的人口流向低纬度和高纬度避难所。在冰盖回缩期间形成二次接触或缝合区,通过促进以前孤立的种群之间的遗传连通性,对遗传多样性产生了重要影响。Brant鹅(Brantabernicla)是一种海上迁徙水禽(Anseriformes)物种,几乎只使用沿海栖息地。在北美,鹅的特征是两个表型不同的亚种,它们利用北太平洋和大西洋的分离繁殖和越冬区。在加拿大西部高北极地区,鹅由具有中间表型的个体组成,很少在该区域外筑巢。我们使用线粒体DNA(mtDNA)控制区序列数据和微卫星基因座,研究了来自每个亚种和由中间表型组成的区域的野鹅种群的遗传结构。我们在两种标记类型中都发现了强烈的东西分区,与避难所种群一致。在亚种内,在mtDNA上也观察到结构,而微卫星数据表明仅存在两个不同的遗传簇。由于mtDNA和核基因型被分配给两个亚种,因此西部高北极(WHA)似乎是大西洋和太平洋血统的次要接触区,在该地区观察到混合个体。WHA以外的mtDNA序列数据表明,大西洋和太平洋越冬种群之间没有或非常有限的混合,这与已发布的条带和遥测数据一致。我们的研究表明,尽管WHA中的燕麦鹅不是遗传上独特的谱系,该地区可能是遗传多样性的储库,并且鉴于该物种的低生殖输出潜力,该地区可能是具有高保护价值的地区。
    Genetic variation in Arctic species is often influenced by vicariance during the Pleistocene, as ice sheets fragmented the landscape and displaced populations to low- and high-latitude refugia. The formation of secondary contact or suture zones during periods of ice sheet retraction has important consequences on genetic diversity by facilitating genetic connectivity between formerly isolated populations. Brant geese (Branta bernicla) are a maritime migratory waterfowl (Anseriformes) species that almost exclusively uses coastal habitats. Within North America, brant geese are characterized by two phenotypically distinct subspecies that utilize disjunct breeding and wintering areas in the northern Pacific and Atlantic. In the Western High Arctic of Canada, brant geese consist of individuals with an intermediate phenotype that are rarely observed nesting outside this region. We examined the genetic structure of brant geese populations from each subspecies and areas consisting of intermediate phenotypes using mitochondrial DNA (mtDNA) control region sequence data and microsatellite loci. We found a strong east-west partition in both marker types consistent with refugial populations. Within subspecies, structure was also observed at mtDNA while microsatellite data suggested the presence of only two distinct genetic clusters. The Western High Arctic (WHA) appears to be a secondary contact zone for both Atlantic and Pacific lineages as mtDNA and nuclear genotypes were assigned to both subspecies, and admixed individuals were observed in this region. The mtDNA sequence data outside WHA suggests no or very restricted intermixing between Atlantic and Pacific wintering populations which is consistent with published banding and telemetry data. Our study indicates that, although brant geese in the WHA are not a genetically distinct lineage, this region may act as a reservoir of genetic diversity and may be an area of high conservation value given the potential of low reproductive output in this species.
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  • 文章类型: Journal Article
    捕食者-猎物相互作用的变化通常被认为是重大进化变化的驱动因素。一个突出的例子是中生代海洋革命(MMR)期间浅海组合的巨大变化,包括钩状腕足动物,变得受限制和不那么多样化。目前,浅水温带和极地腕足动物可以很大,但在热带地区,它们很小。相比之下,我们证明,整个侏罗纪大型腕足动物都发生在浅层地点,从极地到热带纬度,但在热带地区的后期不存在。这些变化在两个主要顺序(Rhynchonellida和Terebratulida)中同时发生,并且在Terebratulida内的两个子顺序谱系(terebratulinids和terebratellinids)中也独立发生。与MMR相关的放牧和捕食压力的增加可能是这种模式的原因。然而,我们注意到,目前的许多环境都支持大型腕足动物和高密度的放牧物种,并表明这种模式更适合热带浅水中双重捕食的加剧。
    Changes in predator-prey interactions are often implicated as drivers of major evolutionary change. A prominent example is the dramatic changes in shallow marine assemblages during the Mesozoic Marine Revolution (MMR) when major clades, including rhynchonelliform brachiopods, became restricted and less diverse. Currently, shallow-water temperate and polar brachiopods can be large, but in the tropics, they are small. By contrast, we demonstrate that throughout the Jurassic large brachiopods occurred in shallow sites, from polar to tropical latitudes, but are absent in later periods from tropical areas. These changes occurred in parallel in both major orders (Rhynchonellida and Terebratulida) and also independently within the two sub-ordinal lineages within the Terebratulida (terebratulinids and terebratellinids). Increases in both grazing and predation pressures associated with the MMR might account for this pattern. However, we note that many current environments support both large brachiopods and high densities of grazing species and suggest that the pattern fits more closely to the intensification of durophagous predation in shallow tropical waters.
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  • 文章类型: Journal Article
    在本研究中,使用来自CapeFold山(CFM)和大悬崖(Drakensberg山脉)的物种的mtDNA序列数据,检查了淡水蟹(Potamonautes)山枝中的进化关系。我们进行了系统发育分析,发散时间估计,以及祖先地区的重建,以探索该高原进化枝的形成时期并了解其生物地理历史。此外,我们使用ASAP应用了四种物种划界方法,bPTP,bGMYC,和后一种进化枝的STACEY。贝叶斯系统发育分析检索到了由两个主要姐妹进化枝组成的单系淡水蟹进化枝,一个由CapeFold(进化枝A)组成,两个由Drakensberg山脉(进化枝B)组成。发散时间估计表明,这两个进化枝经历了Mio/上新世枝层形成。在CFM进化枝(A)内,P.amathole(Amathola山脉)是P.parvispina(Cederberg和Kouebokkeveld山脉)的姐妹,后者是P.parvicorpus(开普半岛,Jonkershoek,和Helderberg山脉)的姐姐P.tuerkayi(奥弗伯格山脉)和P.brincki(霍滕托特荷兰山脉)。在Drakensberg山进化枝(B)内,我们观察到原位多样化。来自德拉肯斯堡山脉中南部的标本(DargleForest,因贾苏提,Karkloof,和Impendle)代表一个新的未描述的谱系Potamonautessp。11月。1.来自北部德拉肯斯堡的第二个进化枝,代表P.Clarus,是中央德拉肯斯堡山脉进化枝的姐妹,该进化枝包括P.depressus,而P.depressus又是来自东开普省的P.baziya的姐妹。物种定界方法的应用普遍高估了物种的数量。生物地理分析表明,东开普省是最有可能的祖先地区。进化枝A(CapeFoldMountains)和进化枝B(DrakensbergMountains)的代表物种的生态位模型表明,温度和降雨是区分这两个进化枝的主要非生物驱动因素。我们的数据支持山脉梯度形态假说。
    During the present study, the evolutionary relationship within a clade of mountain clade of freshwater crabs (Potamonautes) was examined using mtDNA sequence data for species from the Cape Fold Mountain (CFM) and Great Escarpment (Drakensberg Mountain range). We undertook phylogenetic analyses, divergence time estimation, and an ancestral area reconstruction to explore the period of cladogenesis and understand the biogeographic history in this high-altitude clade. Furthermore, we applied four species delimitation methods using ASAP, bPTP, bGMYC, and STACEY on the latter clade. Bayesian phylogenetic analyses retrieved a monophyletic freshwater crab clade comprised of two major sister clades, one comprised of the Cape Fold (clade A) and two comprised of Drakensberg Mountains (clade B) species. Divergence time estimation indicated that the two clades underwent Mio/Pliocene cladogenesis. Within the CFM clade (A), P. amathole (Amathola Mountains) was sister to P. parvispina (Cederberg and Kouebokkeveld Mountains) and the latter species were sister to P. parvicorpus (Cape Peninsula, Jonkershoek, and Helderberg Mountains) sister to P. tuerkayi (Overberg Mountains) and P. brincki (Hottentots Holland Mountains). Within the Drakensberg Mountain clade (B), we observed in situ diversification. Specimens from the southcentral Drakensberg Mountains (Dargle Forest, Injasuti, Karkloof, and Impendle) represent a new undescribed lineage Potamonautes sp. nov. 1. The second clade from the northern Drakensberg, representing P. clarus, was sister to a central Drakensberg Mountain clade that comprised P. depressus that was in turn sister to P. baziya from the Eastern Cape Province. The application of species delimitation methods generally overestimated the number of species. The biogeographic analyses indicated that the Eastern Cape Province is the most likely ancestral range area. Ecological niche modelling of representative species in clades A (Cape Fold Mountains) and B (Drakensberg Mountains) demonstrated that temperature and rainfall were the major abiotic drivers that differentiated the two clades. Our data favours the mountain gradient speciation hypothesis.
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  • 文章类型: Journal Article
    东亚亚热带常绿阔叶林(EBLF)由具有不同地形和环境条件的西部和东部亚区域组成。预测两个子区域中植物随时间的分布变化是不同的,但是这种差异很少被调查。
    在最后一次冰川最大值(LGM)期间,有53种木兰科物种(西部22种,东部分区域31种)的潜在分布,present,2070年代是使用MaxEnt基于58个环境变量预测的。分析了分布范围大小和质心随时间的变化。覆盖物种级潜在栖息地,以揭示物种多样性分布,并将随时间的分布叠加以发现长期避难所。
    目前,电位分布明显大于发生点显示的电位分布。在LGM期间,西部次区域的20/22物种通过向下和向南迁移经历了范围大小的增加,东部次区域(27/31种)的范围减小伴随着向北和向东迁移。在未来,范围大小下降和向北移动都将被发现;西部次区域的大多数(20/22种)物种将存在向西北移动,而西北和东北向转移都将发生在东部次区域。多样性热点在西部次区域经历了过去轻微的南移,未来向上向山区转移;在东部次区域,过去在中国东部发生了萎缩,未来在所有地区都出现了萎缩。在整个EBLF地区的山区发现了长期的避难所保存多样性。
    在两个分区域中揭示了从过去到现在的分布变化的显着差异以及从现在到将来的类似分布变化。两个分区的物种多样性从过去到未来都没有经历重大转变,木兰科植物可以保存在整个EBLF的山区。
    UNASSIGNED: East Asian subtropical evergreen broad-leaved forests (EBLFs) are composed of western and eastern subregions with different topographical and environmental conditions. The distribution shifts over time of plants in the two subregions are predicted to be different, but the difference has seldom been investigated.
    UNASSIGNED: Potential distributions of 53 Magnoliaceae species (22 in the western and 31 in the eastern subregion) during the last glacial maximum (LGM), present, and the 2070s were predicted using MaxEnt based on 58 environmental variables. The changes in the distribution range size and centroid over time were analyzed. Species-level potential habitats were overlaid to uncover species diversity distribution, and the distributions over time were overlaid to discover long-term refugia.
    UNASSIGNED: At present, the potential distributions are significantly larger than those shown by the occurrence points. During the LGM, 20/22 species in the western subregion experienced increases in range size through downwards and southward migrations, while decreases in range size in the eastern subregion (27/31 species) were accompanied by northward and eastward migrations. In the future, range size declines and northward shifts will both be found; northwestward shifts will exist in most (20/22 species) species in the western subregion, while both northwest- and northeastward shifts will occur in the eastern subregion. The diversity hotspots experienced a slight southward shift in the past and upwards to the mountain region in the future in the western subregion; in the eastern subregion, shrinks occurred in eastern China in the past and shrinks were shown in all regions in the future. Long-term refugia-preserving diversity was found in the mountains across the entire EBLFs region.
    UNASSIGNED: Significant differences in distribution shifts from past to present and similar distribution shifts from present to future are revealed in the two subregions. Species diversity in both subregions experienced no significant shifts from past to future, and Magnoliaceae plants could be preserved in mountainous regions throughout the EBLFs.
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  • 文章类型: Journal Article
    由于自古近纪以来的全球气候变冷和干旱化,新近纪植物区系的成员从北半球灭绝或局限于一些避难所。对于一些物种来说,最后的减少/灭绝发生在更新世,但是到目前为止,还有一些人在气候变化中幸存下来。这发生在板栗,一种在欧洲具有很高商业价值的物种,也是高加索森林生物多样性的重要组成部分。与欧洲范围相反,尚未阐明其孤立的高加索物种的历史生物地理学和种群遗传结构。这里,根据对来自高加索地区的21个自然种群和来自欧洲的一个自然种群的调查,我们提供了可能的生物地理重建和遗传多样性细节。通过应用贝叶斯推理,物种分布建模和化石花粉数据,我们估计(i)中更新世高加索-欧洲分歧的时间,(ii)高加索血统之间的分歧时间和(iii)概述了物种的冰川避难所。与中更新世早期过渡有关的气候变化被认为是该物种种内差异和欧洲-高加索分离的主要驱动因素,而最后一个冰川周期的影响是微不足道的。
    Due to global climate cooling and aridification since the Paleogene, members of the Neogene flora were extirpated from the Northern Hemisphere or were confined to a few refugial areas. For some species, the final reduction/extinction came in the Pleistocene, but some others have survived climatic transformations up to the present. This has occurred in Castanea sativa, a species of high commercial value in Europe and a significant component of the Caucasian forests\' biodiversity. In contrast to the European range, neither the historical biogeography nor the population genetic structure of the species in its isolated Caucasian range has been clarified. Here, based on a survey of 21 natural populations from the Caucasus and a single one from Europe, we provide a likely biogeographic reconstruction and genetic diversity details. By applying Bayesian inference, species distribution modelling and fossil pollen data, we estimated (i) the time of the Caucasian-European divergence during the Middle Pleistocene, (ii) the time of divergence among Caucasian lineages and (iii) outlined the glacial refugia for species. The climate changes related to the Early-Middle Pleistocene Transition are proposed as the major drivers of the intraspecific divergence and European-Caucasian disjunction for the species, while the impact of the last glacial cycle was of marginal importance.
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  • 文章类型: Journal Article
    背景:更新世和山地隆升期间的气候波动是影响地理分布的重要驱动力。这里,我们问一年生植物对更新世冰川周期的反应。
    方法:在本研究中,我们分析了青藏高原(QTP)特有的一年生草本植物SwertiatetraapteraMaxim(龙胆科)的人口统计学历史。基于两个母系遗传的叶绿体片段(trnL-trnF和trnS-trnG),对来自35个四翅目沙门氏菌种群的301个个体进行了分析。将系统地理学分析与物种分布模型相结合,以检测四翅目S.的遗传变异。
    结果:四翅目沙门氏菌的遗传多样性较高,可能是由于其广泛的自然范围,高比例的地方性单倍型和进化史。在四翅目沙门氏菌中鉴定出54个单倍型。只有少数单倍型广泛存在(Hap_4、Hap_1、Hap_3),它们分散在目前的四翅目沙门氏菌地理范围内,而许多单倍型仅限于单一种群。cpDNA数据集显示,在四翅目沙门氏菌的分布范围内缺乏系统地理结构。分子变异分析表明,大多数遗传变异是在种群内发现的(70.51%)。此外,单倍型的关系几乎完全无法通过系统发育重建解决。失配分布分析和中性测试均显示了最近在四翅目链球菌分布范围内的扩展。MaxEnt分析显示,四翅目昆虫在最后一次冰川最大值(LGM)期间分布范围窄,在当前时间分布范围宽,随着对未来的预测,四翅目昆虫的分布范围不断扩大。
    结论:我们的研究表明,四翅目沙门氏菌目前的地理和遗传分布可能是由第四纪形成的。第四纪冰川期间存在四翅目的多个微避难所。快速的种内多样化和杂交和/或基因渗入可能在塑造四翅目链球菌的当前分布模式中起着至关重要的作用。在LGM期间,四翅目的分布范围似乎经历了收缩;在未来,当全球气候随着二氧化碳水平的上升而变暖时,四翅目昆虫的分布将会扩大。
    BACKGROUND: Climate fluctuations during the Pleistocene and mountain uplift are vital driving forces affecting geographic distribution. Here, we ask how an annual plant responded to the Pleistocene glacial cycles.
    METHODS: In this study, we analyzed the population demographic history of the annual herb Swertia tetraptera Maxim (Gentianaceae) endemic to Qinghai-Tibetan Plateau (QTP). A total of 301 individuals from 35 populations of S. tetraptera were analyzed based on two maternally inherited chloroplast fragments (trnL-trnF and trnS-trnG). Phylogeographic analysis was combined with species distribution modeling to detect the genetic variations in S. tetraptera.
    RESULTS: The genetic diversity of S. tetraptera was high, likely due to its wide natural range, high proportion of endemic haplotypes and evolutionary history. Fifty-four haplotypes were identified in S. tetraptera. Only a few haplotypes were widespread (Hap_4, Hap_1, Hap_3), which were dispersed throughout the present geographical range of S. tetraptera, while many haplotypes were confined to single populations. The cpDNA dataset showed that phylogeographic structuring was lacking across the distribution range of S. tetraptera. Analyses of molecular variance showed that most genetic variation was found within populations (70.51%). In addition, the relationships of the haplotypes were almost completely unresolved by phylogenetic reconstruction. Both mismatch distribution analysis and neutrality tests showed a recent expansion across the distribution range of S. tetraptera. The MaxEnt analysis showed that S. tetraptera had a narrow distribution range during the Last Glacial Maximum (LGM) and a wide distribution range during the current time, with predictions into the future showing the distribution range of S. tetraptera expanding.
    CONCLUSIONS: Our study implies that the current geographic and genetic distribution of S. tetraptera is likely to have been shaped by Quaternary periods. Multiple microrefugia of S. tetraptera existed during Quaternary glaciations. Rapid intraspecific diversification and hybridization and/or introgression may have played a vital role in shaping the current distribution patterns of S. tetraptera. The distribution range of S. tetraptera appeared to have experienced contraction during the LGM; in the future, when the global climate becomes warmer with rising carbon dioxide levels, the distribution of S. tetraptera will expand.
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