高山植物条纹狭蕊龙胆的分子亲缘地理学研究

草本植物由于较短的生活周期以及对环境变化的敏感性,可能会更好地揭示第四纪冰期以来植物居群变化的历史过程.分子亲缘地理学研究是揭示动植物居群历史的有力工具,但到目前为止对青藏高原草本植物的分子亲缘地理学研究几乎是空白.因此,本文选择在青藏高原及邻近地区生长的一年生高山草本植物条纹狭蕊龙胆为研究对象,进行了13个居群155个个体的叶绿体基因组(cpDNA)非编码片段trnH(GuG)-psbA基因间区序列变异检测,共发现7种单倍型,其中单倍型H印A是分布最广的,而单倍型Hap E、Hap F和Hap G是拥有的居群所特有的.青藏高原东北部、东部及邻近地区的每个居群拥有的单倍型非常单一,而高原东南部横断山区的单倍型分布很集中,遗传多样性也相对较高.分子变异分析(AMOVA)结果表明整个分布区条纹狭蕊龙胆的遗传变异主要存在于居群间(73.05%),且居群问的遗传分化很高(GsT=0.805,FsT=0.731,NsT=0.859),有着显著的亲缘地理学结构(NsT>Gsr,P<0.05)和较低的居群间的平均基因流(Nm=0.184).结合巢式支系法分析(NCA),根据本文的研究结果推测青藏高原东南部横断山区是该植物第四纪冰期时可能的避难所,而且在间冰期或冰期后.伴随着异域片段化和过去片段化从避难所发生范围扩张而形成当前单倍型及居群的分布格局.     

基于叶绿体DNA变异研究高山植物偏花报春的种内谱系地理结构

横断山地区是许多温带植物的冰期避难所。为揭示该地区分布物种的亲缘地理结构, 检测了该地区特有、分布相对较为普遍的偏花报春Primula secundiflora的叶绿体trnL-trnF和rps16区序列变异。研究了11个居群109个个体, 一共发现了15种单倍型。只有一种单倍型为3个居群所共有, 其他单倍型都只存在于单个居群内。总的遗传多样性较高(HT=0.966), 但居群内遗传多样性较低(HS=0.178)。尽管种内形态十分一致, 居群间却存在高水平的遗传分化(FST=0.976)。NST (0.982)显著高于GST (0.816), 表明偏花报春在居群间存在明显的亲缘地理结构。单倍型聚成四个主要的分支: 三个分支的单倍型分布在北部, 而另一分支的单倍型分布在南部。四个分支的隔离分布表明该物种在冰期存在多个避难所。未发现在其他温带物种中广泛存在的间冰期或者冰期后物种分布范围的统一扩张现象。但是, 在气候变迁过程中由于居群增长-缩小反复发生, 多数居群的遗传多样性降低。这些推断也被巢式分支分析所证实, 距离隔离而导致的限制性基因流以及异域片断化被认为是该物种现有单倍型分布格局形成的主要原因。这种独特的谱系地理结构主要是由于气候变迁与该地区复杂的地质环境相结合造成的。     

Genetic diversity pattern of Stipa purpurea populations in the hinterland of Qinghai–Tibet Plateau

Stipa purpurea is among constructive endemic species in alpine meadow and steppe on the Qinghai–Tibet Plateau. To reveal the genetic diversity of this species and its relationship with geographic distribution pattern, we sampled eight populations across a northward transect with an increasing aridity gradient in the hinterland of Qinghai–Tibet Plateau. Their genetic diversity was quantified using eight intersimple sequence repeat (ISSR) primers. We found that S. purpurea had relatively low genetic diversity ( H _e = 0.135) but significant genetic differentiation among populations ( G _st = 0.391), indicating relatively more genetic diversity retained within populations. A Mantel test revealed a significant relationship between genetic and geographic distance in the S. purpurea populations. The genetic diversity tended to decrease with increasing latitude and longitude, while no significant relationship was found between genetic diversity and altitude, suggesting the possible influences of humidity and temperature on genetic diversity of alpine plant. We propose conservation measures for this plant on the plateau.     

Genetic structure and differentiation of Gentiana atuntsiensis W. W. Smith and G. striolata T. N. Ho (Gentianaceae) as revealed by ISSR markers

The Hengduan Mountains are the core region of the Himalaya hotspot, and are renowned for their high levels of endemism. Gentiana atuntsiensis and G. striolata are two closely related and morphologically similar species endemic to this region. In this study, inter-simple sequence repeat (ISSR) markers were used to investigate the genetic structure within these two species, as well as the differentiation between them. An analysis of molecular variance-derived estimate demonstrated only 13.5% of genetic differentiation between the two species. Considering their adjacent distribution patterns, low genetic divergence, and clear clustering into two groups, it is hypothesized that the two species arose from a rapid and recent speciation event induced mainly by geographical isolation. A relatively high level of genetic diversity was revealed in each species (Shannon's index of diversity: H _sp = 0.324 and 0.391; H _pop = 0.225 and 0.274; for G. atuntsiensis and G. striolata , respectively). Most of the genetic variation was partitioned within populations ( Ø _ST = 0.232 and 0.226 in G. atuntsiensis and G. striolata , respectively). The large population sizes, outcrossing breeding system, and small, light seeds that disperse widely may explain the genetic structure in both species.  © 2007 The Linnean Society of London. Botanical Journal of the Linnean Society , 2007, 154 , 225–232.     

Phylogeography of the Qinghai-Tibetan Plateau endemic Juniperus przewalskii (Cupressaceae) inferred from chloroplast DNA sequence variation

The vegetation of the northeast Qinghai-Tibetan Plateau is dominated by alpine meadow and desert-steppe with sparse forests scattered within it. To obtain a better understanding of the phylogeography of one constituent species of the forests in this region, we examined chloroplast trnT-trnF and trnS-trnG sequence variation within Juniperus przewalskii, a key endemic tree species. Sequence data were obtained from 392 trees in 20 populations covering the entire distribution range of the species. Six cpDNA haplotypes were identified. Significant population subdivision was detected (G(ST) = 0.772, N(ST) = 0.834), suggesting low levels of recurrent gene flow among populations and significant phylogeographic structure (N(ST) > G(ST), P < 0.05). Eight of the nine disjunct populations surveyed on the high-elevation northeast plateau were fixed for a single haplotype (A), while the remaining, more westerly population, contained the same haplotype at high frequency together with two low frequency haplotypes (C and F). In contrast, most populations that occurred at lower altitudes at the plateau edge were fixed or nearly fixed for one of two haplotypes, A or E. However, two plateau edge populations had haplotype compositions different from the rest. In one, four haplotypes (A, B, D and E) were present at approximately equivalent frequencies, which might reflect a larger refugium in the area of this population during the last glacial period. Phylogenetic analysis indicated that the most widely distributed haplotype A is not ancestral to other haplotypes. The contrasting phylogeographic structures of the haplotype-rich plateau edge area and the almost haplotype-uniform plateau platform region indicate that the plateau platform was recolonized by J. przewalskii during the most recent postglacial period. This is supported by the findings of a nested clade analysis, which inferred that postglacial range expansion from the plateau edge followed by recent fragmentation is largely responsible for the present-day spatial distribution of cpDNA haplotypes within the species.     

Strong genetic differentiation of the East-Himalayan <Emphasis Type="Italic">Megacodon stylophorus</Emphasis> (Gentianaceae) detected by Inter-Simple Sequence Repeats (ISSR)

Megacodon stylophorus (Clarke) Smith is a perennial alpine herb endemic to the species-rich eastern Himalayan region. Its populations are locally scattered as isolated patches throughout this region. Genetic variation within and among six populations of this species was assessed using ISSR fingerprinting with 13 primers. High levels of genetic diversity exist within species (P = 69.83%, H_T = 0.1949 and H_sp = 0.3047), while the within-population diversity is low (P = 11.21%, H_E = 0.0532 and H_pop = 0.0792). Extraordinarily high levels of genetic differentiation were detected among populations based on various statistics, including Neis genetic diversity analysis (72.7%), Shannons diversity index (74.01%) and AMOVA (80.70%). That is, populations shared low levels of genetic identity (I = 0.8203 ± 0.0430). This genetic structure was probably due to severe genetic drift of the small-sized patchy populations resulting from postglacial habitat fragmentations. The observed genetic structure of the populations implies that as many populations as possible should be considered for any in situ and ex situ conservation practice on this species.     

Intraspecific differentiation of Allium wallichii (Amaryllidaceae) inferred from chloroplast DNA and internal transcribed spacer fragments

In the present study, we used two chloroplast DNA (cpDNA) fragments (trnL-F and rps16) and the nuclear ribosomal internal transcribed spacer (ITS) sequence data to examine intraspecific differentiation and phylogeographical history of Allium wallichii. Based on wide scale sampling (28 populations and 174 individuals) across the entire distribution range of this species, 33 cpDNA haplotypes and 25 ITS ribotypes were detected in our investigation. These cpDNA haplotypes were divided into three major lineages, which was further supported by the ITS phylogenetic results. High haplotype/ribotype diversity and population differentiation, together with most of the haplotypes/ribotypes being exclusive to single populations, implied restricted gene flow among populations and significant geographical isolation. Nearly all populations with high haplotype/ribotype diversity were found in the Hengduan Mountain Region (HMR), whereas the populations of the Himalayas and Nanling Mountains showed a lower level, suggesting the HMR might serve as a potential divergence center for A. wallichii. The main lineages of A. wallichii diverged from each other between Mid–Late Pliocene and Early Quaternary based on two sets of molecular markers, indicating that the Quaternary climatic fluctuation could not have contributed greatly to the divergence of the main lineages of A. wallichii. Instead, the intricate topography and heterogeneous habitats resulting from the drastic uplift of the Qinghai–Tibet Plateau from the Late Pliocene could be responsible for the intraspecific differentiation of A. wallichii. The present study further highlights the importance of geographic isolation and habitat heterogeneity in shaping and maintaining high species diversity within the HMR.     

Two new species of Panorpa (Mecoptera,Panorpidae) from the Hengduan Mountains in Yunnan,China

Two new species of the genus Panorpa Linnaeus, 1758 are described from the Hengduan Mountains in Yunnan, China. Panorpa diqingensis sp. n. can be distinguished from its congeners by vertex dark brown, and occiput yellow; pleura dark brown; gonocoxites bearing a cluster of stout black setae on inner apex; parameres S-shaped in male genitalia. Panorpa dispergens sp. n. can be readily differentiated from other Panorpa species by apical band with a hyaline spot in wings; gonocoxites with a cluster of stout dark brown setae and 3–5 long setae on inner apex; female medigynium with a pair of basal plates. The number of Panorpa species in Yunnan is raised to six. A key to Yunnan species of Panorpa is presented.     

Five new species of Dicerapanorpa Zhong & Hua (Mecoptera,Panorpidae) from Yunnan,China

Five new scorpionfly species of the genus Dicerapanorpa Zhong and Hua, 2013 are described and illustrated from Yunnan Province, China. Dicerapanorpa macula sp. n. can be readily recognized by all branches of paramere parallel, basal and mesal branches extending well beyond basal process of gonostylus in male, and posterior arm of medigynium short and stout in female. Dicerapanorpa deqenensis sp. n. is characterized by basal branch of paramere as long as lateral branch and ventral valve of aedeagus nearly reaching apex of gonocoxite in male, and medigynium with paired auricular lateral processes in female. Dicerapanorpa tanae sp. n. is unique by genital bulb broad and spherical, basal branch of paramere short, and lateral branches curved convergently and parallel apically in male, and main plate of medigynium rounded in female. Dicerapanorpa tenuis sp. n. is distinguishable by hypovalve with largely expanded and inward curved apex and all branches of paramere reaching or exceeding apex of gonocoxite in male, and medigynium slender in female. Dicerapanorpa zhongdianensis sp. n. is characterized by basal branches of paramere parallel and mesal branches curved convergently in male, and main plate of medigynium subtriangular with a pair of auricular lateral processes in female. The species number of Dicerapanorpa is increased to thirteen.LSID: www.zoobank.org/urn:lsid:zoobank.org:pub:A4490511-C475-4C5B-9E89-4BF4EBAA2137     

Substantial genetic substructuring in southeastern and alpine Australia revealed by molecular phylogeography of the Egernia whitii (Lacertilia: Scincidae) species group

Palaeoclimatic events and biogeographical processes since the mid-Tertiary are believed to have strongly influenced the evolution and distribution of the terrestrial vertebrate fauna of southeastern Australia. We examined the phylogeography of the temperate-adapted members of the Egernia whitii species group, a group of skinks that comprise both widespread low- to mid-elevation (E. whitii) and montane-restricted species (Egernia guthega, Egernia montana), in order to obtain important insights into the influence of past biogeographical processes on the herpetofauna of southeastern Australia. Sequence data were obtained from all six temperate-adapted species within the E. whitii species group, and specifically from across the distributional ranges of E. whitii, E. guthega and E. montana. We targeted a fragment of the ND4 mitochondrial gene (696 bp) and analysed the data using maximum likelihood and Bayesian methods. Our data reveal a deep phylogeographical break in the east Gippsland region of Victoria between 'northern' (Queensland, New South Wales, Australian Capital Territory) and 'southern' (Victoria, Tasmania, South Australia) populations of E. whitii. This divergence appears to have occurred during the late Miocene-Pliocene, with the Gippsland basin possibly forming a geographical barrier to dispersal. Substantial structuring within both the 'northern' and the 'southern' clades is consistent with the effects of Plio-Pleistocene glacial-interglacial cycles. Pleistocene glacial cycles also appear to have shaped the phylogeographical patterns observed in the alpine species, E. guthega and E. montana. We used our results to examine the biogeographical process that led to the origin and subsequent diversification of the lowland and alpine herpetofauna of southeastern Australia.     

Frequent chloroplast capture among Isodon (Lamiaceae) species in Japan revealed by phylogenies based on variation in chloroplast and nuclear DNA

A recent phylogenetic study based only on chloroplast DNA (cpDNA) variation revealed that populations of an Isodon species are frequently embedded paraphyletically among other Isodon species. This phylogenetic discrepancy between species taxonomy and molecular phylogeny was considered to have resulted from chloroplast DNA captures and/or incomplete lineage sorting. To elucidate which of these factors was mainly responsible for the observed phylogenetic pattern, we performed phylogenetic analyses of multiple populations of Isodon species in Japan using cpDNA variation, three single-copy nuclear genes, and double-digest restriction-site-associated DNA sequencing (ddRAD-seq). Although a species often shared chlorotypes with other species, our phylogenetical analyses based on variation in the three single-copy nuclear genes and the ddRAD-seq data showed that most populations belonging to the same species were monophyletic at the species level, suggesting that chloroplast capture may have frequently occurred between Isodon species. Some populations of an intraspecific taxon were embedded paraphyletically within the species, regardless of the large amount of phylogenetic information in nuclear DNA; this incongruity may have resulted from incomplete lineage sorting.     

Molecular systematics and biogeography of Crawfurdia, Metagentiana and Tripterospermum (Gentianaceae) based on nuclear ribosomal and plastid DNA sequences

BACKGROUND AND AIMS: The systematic position of the genus Metagentiana and its phylogenetic relationships with Crawfurdia, Gentiana and Tripterospermum have not been explicitly addressed. These four genera belong to one of two subtribes (Gentianinae) of Gentianeae. The aim of this paper is to examine the systematic position of Crawfurdia, Metagentiana and Tripterospermum and to clarify their phylogenetic affinities more clearly using ITS and trnL intron sequences. METHODS: Nucleotide sequences from the internal transcribed spacers (ITS) of nuclear ribosomal DNA and the plastid DNA trnL (UAA) intron were analysed phylogenetically. Ten of fourteen Metagentiana species were sampled, together with 40 species of other genera in the subtribe Gentianinae. KEY RESULTS: The data support several previously published conclusions relating to the separation of Metagentiana from Gentiana and its closer relationships to Crawfurdia and Tripterospermum based on studies of gross morphology, floral anatomy, chromosomes, palynology, embryology and previous molecular data. The molecular clock hypothesis for the tested sequences in subtribe Gentianinae was not supported by the data (P < 0.05), so the clock-independent non-parametric rate smoothing method was used to estimate divergence time. This indicates that the separation of Crawfurdia, Metagentiana and Tripterospermum from Gentiana occurred about 11.4-21.4 Mya (million years ago), and the current species of these three genera diverged at times ranging from 0.4 to 6.2 Mya. CONCLUSIONS: The molecular analyses revealed that Crawfurdia, Metagentiana and Tripterospermum do not merit status as three separate genera, because sampled species of Crawfurdia and Tripterospermum are embedded within Metagentiana. The speciation and rapid radiation of these three genera is likely to have occurred in western China as a result of upthrust of the Himalayas during the late Miocene and the Pleistocene.     

Genetic structure and phylogeography of Pyrus pashia L. (Rosaceae) in Yunnan Province, China, revealed by chloroplast DNA analyses

In this study, we investigated two chloroplast intergenic spacers (accD-psaI and trnL-trnF) for a total of 266 individuals over 22 populations of Pyrus pashia to detect the genetic diversity, genetic, and phylogeographic structure and provide needed information for the development of conservation strategies. Thirteen haplotypes (H1–H13) were recognized. A high level of total diversity was detected (H _T?=?0.746). Analysis of molecular variance indicated that the genetic variation mainly existed within populations, representing 59.61 % of the total variation. Genetic differentiation among populations was high (F _st?=?0.404). A Mantel test did not show a correlation between the genetic and geographic distances (r?=?0.139, P?=?0.09, 1,000 permutations), implying that geographic distance was not critical to gene flow among populations. A significantly higher N _st than G _st (N _st?=?0.420, G _st?=?0.402, P?<?0.05) reflected the phylogeographic structure in P. pashia. While nested clade analyses of clade 2-2 showed that restricted gene flow existed among populations, clades 1-2 and 2-1, and the total cladogram exhibited contiguous range expansion events in P. pashia. Both sum of square deviations and the raggedness index failed to reject the sudden demographic expansion model. The overall population expansion of P. pashia was estimated to occur between 621,000 and 209,000 years ago.