Cross-species chromosome painting in the Perissodactyla: delimitation of homologous regions in Burchell's zebra (Equus burchellii) and the white (Ceratotherium simum) and black rhinoceros (Diceros bicornis)

Conserved chromosomal segments in the black rhinoceros, Diceros bicornis (DB1, 2n = 84), and its African sister-species the white rhinoceros, Ceratotherim simum (CSI, 2n = 82), were detected using Burchell's zebra (Equus burchellii, EBU, 2n = 44) chromosome-specific painting probes supplemented by a subset of those developed for the horse (Equus caballus, ECA, 2n = 64). In total 41 and 42 conserved autosomal segments were identified in C simum and D. bicornis respectively. Only 21 rearrangements (20 fissions and I fusion) are necessary to convert the Burchell's zebra karyotype into that of the white rhinoceros. One fission distinguishes the D. bicornis and C simum karyotypes which, excluding hetero- chromatic differences, are identical in all respects at this level of resolution. Most Burchell's zebra chromosomes correspond to two rhinoceros chromosomes although in four instances (EBU 18, 19, 20 and 21) whole chromosome synteny has been retained among these species. In contrast, one rhinoceros chromosome (DBI1, CSI1) comprises two separate Burchell's zebra chromosomes (EBU11 and EBU17). In spite of the high diploid numbers of the two rhinoceros species their karyotypes are surprisingly conserved offering a glimpse of the putative ancestral perissodactyl condition and a broader understanding of genome organization in mammals. Copyright (C) 2003 S. Karger AG, Base

星果草属（毛茛科）的系统学研究

星果草属至今仍包括两个种，它在毛茛科中的系统位置存在争议。本文针对该属的物种划分以及它在毛茛科中的系统位置所存在的问题，在云南东北和四川西南交界处，选择了5个居群（包括典型的近全缘型、裂叶型以及它们的中间类型），研究了16个形态性状的变异式样和规律;在扫描电镜下观察了它们的花粉形态，在光镜下统计了4个居群的花粉萌发孔类型;对这5个居群12个酶系统进行了等位酶分析，获得了19个位点的资料;对星果草属及相关的3个属进行了胚胎学研究，获得了星果草属较完整的胚胎学资料 和相关属的部分胚胎学特征。综合上述研究结果和前人的研究资料，对星果草属的形态变异、居群分化、种类划分和它的系统位置进行了分析和讨论，结果如下： l.形态上出现了中间类型是该属存在物种划分问题的主要原因。作者通过形态性状的分析发现，以前作为该属现存两个种的鉴别性状（叶形、叶片大小、植株高矮和叶柄被毛与否）为不稳定的性状，在居群内或居群间呈现连续变异，不能作为分种的鉴别性状;我们考察了根、花部器官的性状以后也未发现它们存在明显间断的性状。 2.居群水平的孢粉学研究表明，三种萌发孔类型（散孔型、散沟型以及它们的中间类型）出现在同一居群内，说明该性状在星果草属的种类划分中具有有限的系统学意义。值得提出的是萌发孔类型在不同居群中出现的频率不同，这种频率与叶形是相关的：叶片裂得越深，散孔类型的花粉所占的比例越大;反之，叶片裂得越浅，散沟类型的花粉所占的比例越大。 3.通过对这5个居群的细胞学研究，作者发现它们均为二倍体(2n=16)，染色体从大到小逐渐过渡，不具有二型性，为R-型染色体;绥江与马边居群（均为典型的裂叶型）的核型资料表明它们的第一对染色体短臂上具有随体。该结果不同于杨亲二等对裂叶型的核型报道。为了探讨星果草属的进化机制还有必要对它的细胞学做进一步研究。 4.等位酶资料表明居群间的基因分化系数达到53.4%，说明居群间遗传分化程度较高。星果草属植物以营养繁殖为主，种子传播主要以重力所介导，又是高山或亚高山分布的植物，这些因素都不利于居群间的基因交流，致使居群间发生很强的遗传分化;居群间的遗传一致度值变化范围为0. 723--0. 912，其中峨眉居群（大多为典型的近全缘型）与绥江居群（典型的裂叶型）的遗传一致度值(0. 845)，仅稍低于马边居群与绥江居群的遗传一致度值(0.912);聚类结果表明这5个居群分为两支，峨眉居群与天全居群聚为一支;其余三个居群聚为另一支，这与与形态分化相吻合。 5.该属胚胎学不少特征与毛莨科其它属相似：花药壁发育为双子叶型，腺质绒毡层，胞质分裂为同时型，成熟花粉为二细胞：双珠被，珠孔仅由内珠被形成，蓼型胚囊，胚胎发生属柳叶菜型。但是假厚珠心与双珠被的特殊组合，有别于毛莨科其它类群。我们还首次报道了鸡爪草属、黄连属和人字果属的部分胚胎学特征。 基于以上形态学、孢粉学、细胞学和等位酶的分析结果，作者认为将星果草属处理为单种属，种下分为两个亚种较为合适。并认为星果草属为金莲花亚科中的自然类群，并与金莲花亚科中金莲花族关系较近，给予族的等级较为合适。

The boundary of palaearctic and oriental realms in western China

In the world-wide zoogeographic division, there has been no consentaneous understanding about the delimitation between palaearctic and oriental realms in western China. In this study, we will discuss the division based on amphibian distribution in Shaanxi, Gansu, Sichuan, Yunnan, and Tibet according to species coefficient similarity between each zoogeographic province. The results show that the northern border lies from Qinling Mountains-Feng Xian (Shaanxi)-Debu (Gansu)-Aba (Sichuan)-Batang-Bomi (Tibet), to Linzhi districts, and the southern border is from Taibai-Feng Xian in Shaanxi-Wen Xian (Gansu)-Songpan-Kangding-Daocheng (Sichuan), to Zhongdian-Gongshan in Yunnan, and westward to Motuo and Bomi district in Tibet. (c) 2008 National Natural Science Foundation of China and Chinese Academy of Sciences. Published by Elsevier Limited and Science in China Press. All rights reserved.

A new species of Saussurea (Asteraceae) from Tibet and its systematic position based on ITS sequence analysis

A new species of Saussurea, S. erecta S. W Liu, J. T Pan A J. Q. Liu sp. nov., is described from Tibet. It resembles S. kingii but may be distinguished by having distinct stems and glabrous achenes. Saussurea kingii was placed in sect. Pseudoeriocoryne of subgen. Eriocoryne; this section was circumscribed by acaulescence and an inflorescence with congested capitula surrounded by a rosette of leaves. The discovery of S. erecta with distinct stems, cauline leaves and corymbose capitula blurred the delimitation of sect. Pseudoeriocoryne and suggested that the section may be polyphyletic. Both the close relationship and the significant difference between S. erecta and S. kingii were confirmed by analyses of nrDNA ITS sequences. The resulting phylogenies based on ITS data further suggest that Saussurea sect. Pseudoeriocoryne, as traditionally defined, does not constitute a monophyletic group. The rapid radiation and speciation of Saussurea in the Qinghai-Tibetan Plateau, as inferred from ITS phylogeny, are discussed. (c) 2005 The Linnean Society of London.

Molecular phylogeny and biogeography of the Qinghai-Tibet Plateau endemic Nannoglottis (Asteraceae)

All taxa endemic to the Qinghai-Tibet Plateau are hypothesized to have originated in situ or from immediately adjacent areas because of the relatively recent formation of the plateau since the Pliocene, followed by the large-scaled biota extinction and recession caused by the Quaternary ice sheet. However, identification of specific progenitors remains difficult for some endemics, especially some endemic genera. Nannoglottis, with about eight species endemic to this region, is one such genus. Past taxonomic treatments have suggested its relationships with four different tribes of Asteraceae. We intend to identify the closest relatives of Nannoglottis by evaluating the level of monophyly, tribal delimitation, and systematic position of the genus by using molecular data from ndhF gene, trnL-F, and ITS region sequences. We find that all sampled species of Nannoglottis are a well-defined monophyly. This supports all recent taxonomic treatments of Nannoglottis, in which all sampled species were placed in one broadly re-circumscribed genus. Nannoglottis is most closely related to the Astereae, but stands as an isolated genus as the first diverging lineage of the tribe, without close relatives. A tentative relationship was suggested for Nannoglottis and the next lineage of the tribe was based on the ITS topology, the "basal group," which consists of seven genera from the Southern Hemisphere. Such a relationship is supported by some commonly shared plesiomorphic morphological characters. Despite the very early divergence of Nannoglottis in the Astereae, the tribe must be regarded to have its origin in Southern Hemisphere rather than in Asia, because based on all morphological, molecular, biogeographical, and fossil data, the Asteraceae and its major lineages (tribes) are supposed to have originated in the former area. Long-distance dispersal using Southeast Asia as a steppingstone from Southern Hemisphere to the Qinghai-Tibet Plateau is the most likely explanation for this unusual biogeographic link of Nannoglottis. The 23-32-million-year divergence time between Nannoglottis and the other Astereae estimated by DNA sequences predated the formation of the plateau. This estimation is further favored by the fossil record of the Asteraceae and the possible time of origin of the Astereae. Nannoglottis seems to have reached the Qinghai-Tibet area in the Oligocene-Eocene and then re-diversified with the uplift of the plateau. The molecular infragenetic phylogeny of the genus identifies two distinct clades, which reject the earlier infrageneric classification based on the arrangement of the involucral bracts and the length of the ligules, but agree well with the habits and ecological preferences of its current species. The "alpine shrub" vs. "coniferous forest" divergence within Nannoglottis was estimated at about 3.4 million years ago when the plateau began its first large-scale uplifting and the coniferous vegetation began to appear. Most of the current species at the "coniferous forest" clade of the genus are estimated to have originated from 1.02 to 1.94 million years ago, when the second and third uprisings of the plateau occurred, the climate oscillated and the habitats were strongly changed. The assumed evolution, speciation diversity, and radiation of Nannoglottis based on molecular phylogeny and divergence times agree well with the known geological and paleobotanical histories of the Qinghai-Tibet Plateau. (C) 2002 Elsevier Science (USA). All rights reserved.