Karyological studies on the Sino-Himalayan endemic Soroseris and two related genera of tribe Lactuceae (Asteraceae)

Karyological studies were carried out on ten populations comprising six species of Soroseris in the tribe Lactuceae (Asteraceae), all endemic to the alpine Sino-Himalayan region and poorly known cytogenetically. The single species of Stebbinsia (one population) and two species of Syncalathium (three populations) were also examined for the first time. The basic chromosome number for the three genera is x  = 8. Stebbinsia and most species of Soroseris are diploids with 2 n  = 2 x  = 16 = 14m + 2sm and have a karyotype asymmetry type 1A. Three species of Soroseris are tetraploid (2 n  = 4 x  = 32 = 28m + 4sm). A karyotype of 2 n  = 2 x  = 16 = 14m(2SAT) + 2sm with type 1A asymmetry was found in Syncalathium kawaguchii , and of 2 n  = 2 x  = 16 = 6m + 10sm with type 2A asymmetry for two populations of Syncalathium souliei . The relationships between Soroseris and the other two genera are discussed. Our cytological results suggest that polyploidy plays a minor role in the chromosome evolution of plants from the Himalayan mountains and adjacent regions.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 154 , 79–87.     

Cytological studies on the genus Holcoglossum (Orchidaceae)

The karyotypes of ten species of Holcoglossum (Orchidaceae), a highly endangered and diversified genus from China, were investigated to study the infrageneric relationships, biogeography, and speciation patterns in the Hengduan Mountains. The karyotype formulae of the studied species are as follows: 2 n  = 38 = 20m + 18sm in H. subulifolium , 2 n  = 38 = 22m + 16sm in H. amesianum , 2 n  = 38 = 26m + 12sm (6 SAT) in H. lingulatum , 2 n  = 38 = 26m + 12sm in H. wangii , 2 n  = 38 = 10m + 28sm in H. kimballianum , 2 n  = 38 = 14m + 22sm + 2st in H. flavescens , 2 n  = 38 = 24m + 12sm + 2st in H. rupestre , 2 n  = 38 = 14m + 20sm + 4st in H. sinicum , 2 n  = 38 = 16m + 14sm + 8st in H. weixiense , and 2 n  = 76 in H. tsii . The karyotypes of two tropical species, H. amesianum and H. subulifolium , are the most primitive in the genus, whereas those of four temperate alpine species, H. sinicum , H. rupestre , H. weixiense , and H. flavescens , are more advanced. H. tsii is a tetraploid and H. rupestr e may be one of its ancestors. The low frequency of polyploidy in Holcoglossum in the Hengduan Mountains region supports the conclusion that chromosome stasis during rapid speciation is common there.  © 2007 The Linnean Society of London. Botanical Journal of the Linnean Society , 2007, 154 , 283–288.     

Cytological studies on the Sino-Himalayan endemic Anisodus and four related genera from the tribe Hyoscyameae (Solanaceae) and their systematic and evolutionary implications

Cytological studies were carried out on eight species of five genera ( Anisodus , Atropanthe , Hyoscyamus , Mandragora and Przewalskia ) in the tribe Hyoscyameae (Solanaceae). First chromosome counts were reported in six species: Anisodus luridus , A. acutangulus , A. tanguticus , A. carniolicoides , Atropanthe sinensis and Mandragora caulescens , all with 2 n  = 8 x  = 48. Two records, for Hyoscyamus niger (2 n  = 2 x  = 34) and Przewalskia tangutica (2 n  = 4 x  = 44), were also confirmed. All species studied showed the proximal type of mitotic prophase chromosome condensation pattern. Three types of interphase nuclei were recognized: the round prochromosome type for Anisodus , Atropanthe and Mandragora , the rod prochromosome type for Przewalskia and the complex chromocentre type for Hyoscyamus . The cytological data supported the close relationship of all four species of Anisodus . Evidence from the interphase nuclei and chromosome base numbers supported the traditional classification of Hyoscyameae into two groups, i.e. Physochlaina praealta + Hyoscyamus (complex interphase type and x  = 7, 14, 17) and Przewalskia + Atropanthe + Anisodus + Scopolia + Atropa + Mandragora (prochromosome type and x  = 6, 11). Polyploidy is found in most species of the tribe in the Himalayan–Hengduan Mountains, as well as in the Mediterranean region, west–central Asia and eastern Asia. It seems that it probably occurred very early in Hyoscyameae evolution, before the uplift of the Himalayan–Hengduan Mountains. The Himalayan orogeny might have played a minor role in the polyploid evolution of plants in this tribe.  © 2005 The Linnean Society of London. Botanical Journal of the Linnean Society , 2005, 147 , 457–468.     

Systematic significance of cytology in Cyananthus (Campanulaceae) endemic to the Sino-Himalayan region

Chromosome numbers and the morphology of members of 24 populations representing 15 species of the Sino-Himalayan endemic genus Cyananthus(Campanulaceae) were studied using karyological and numerical taxonomic techniques. The chromosome numbers of these taxa are 2n = 10, 12, 14, 24, 28, and the basic chromosome numbers for the genus are x = 5, 6, 7. All species except C. inflatus Hook. f. & Thoms. and C. microphyllus Edgew. were examined for the first time and a new ploidy level (tetraploidy) is reported in the genus. Chromosome measurement data were analyzed using cluster analysis. The relationships between three sections within Cyananthus and evolutionary trends within the genus are discussed in the light of karyological data. The cytological data suggest that Cyananthus is a relatively primitive genus in Campanulaceae and there is significant division within the genus, and polyploidization may have played an important role in the chromosome evolution and speciation of Cyananthus in the Himalayan–Hengduan Mountains.     

Molecular phylogeny of Solms-laubachia (Brassicaceae) s.l., based on multiple nuclear and plastid DNA sequences, and its biogeographic implications

The Hengduan Mountains region of south-west China is a noted biodiversity,hotspot, but the geographic origins and historical assembly of its rich endemic flora, including the sky-island species of Solms-laubachia Muschl. (Brassicaceae), have been little studied. Previous molecular studies on the phylogeny of Solms-laubachia showed it to be paraphyletic, leading to considerable expansion not only of its taxonomic limits, but also its geographic range, with the inclusion of taxa from outside the Hengduan region. However, these studies provided little resolution of interspecific relationships, preventing inferences about historical biogeography within the clade. In the present study, new sequence data from two nuclear genes (LEAFY and G3pdh) and two chloroplast intergenic spacers (petN-psbM and psbM-trnD) were combined with existing markers to increase phylogenetic signals. Phaeonychium villosum (Maxim.) Al-Shehbaz was found to be nested within Solms-laubachia s.l. In general, phylogenetic relationships appear to be a good predictor of geography, with the Hengduan Mountain endemics embedded in a paraphyletic grade of species from the western Himalayas and central Asia, but they also imply morphological homoplasy. Incongruence was detected between the nuclear and chloroplast gene trees, perhaps resulting from incomplete lineage sorting of ancestral polymorphisms. The crown age of Solms-laubachia s.l. was estimated to be approximately 1.42-3.68 mya, using Bayesian relaxed molecular clock analysis. Historical biogeographic analysis using a parametric dispersal-extinction-cladogenesis model inferred central Asia and the western Himalayas as most probable ancestral range of Solms-laubachia s.l., and estimated higher rates of eastward expansion than westward during the diversification of descendant lineages. In summary, our results suggest that Solms-laubachia s.l. originated during the Pliocene in central Asia, and subsequently migrated eastward into the Hengduan Mountains, colonizing sky-island, alpine scree-slope habitats that may have provided novel ecological opportunity and accelerated speciation, ultimately establishing this region as the present center of diversity of the genus.     

Molecular evidence for allopolyploid speciation and a single origin of the narrow endemic Draba ladina (Brassicaceae)

Draba ladina (Brassicaceae) is a small alpine flower endemic to the Swiss Alps. It occurs exclusively at elevations between 2600 and 3000 m and is restricted to less than a dozen mountains in the Lower Engadin. Morphological characters and polyploidy suggest a hybrid origin. Potential diploid progenitor species are distributed widely and often occur sympatrically. To study the evolutionary history of D. ladina we assessed intra- and interspecific sequence variation at noncoding chloroplast DNA loci and nuclear rDNA ITS sequences in D. ladina and its presumed progenitor species D. aizoides, D. dubia, and D. tomentosa. A single ITS (Internal Transcribed Spacer) genotype was found in each of D. aizoides and D. dubia and two in D. tomentosa. Additivity of ITS sequences of D. aizoides and D. tomentosa was found in D. ladina, supporting the hypothesis of an allotetraploid origin. Intraspecific cpDNA variation was found in all diploid species, but not in D. ladina. The single chloroplast DNA haplotype found in the latter was closest to one cpDNA haplotype found in D. tomentosa, suggesting that D. tomentosa was the maternal parent. These results suggest that D. ladina is a relatively young, presumably postglacial, taxon with a single allopolyploid origin.     

Microsatellites for three distantly related genera in the Brassicaceae

Microsatellites are important genetic markers both in population genetics and for delimitation of closely related species. However, to develop microsatellites for each target organism is expensive and time consuming. In this study, we have therefore developed 65 new microsatellite primers for the species Draba nivalis and tested cross-species and cross-genus transfer success of these primers for two other genera in the Brassicaceae; Cardamine and Smelowskia. Furthermore, 15 previously developed microsatellites were tested for amplification in these three genera. The microsatellite markers that amplify across these genera may be useful for other genera in the Brassicaceae as well.     

The South American genera Brayopsis and Englerocharis (Brassicaceae)

Three species and two subspecies of Erayopsis and two species of Englerocharis are recognized. The generic limits and relationships of the two Andean genera are assessed. Englerocharis pauciflora and B. alpaminae ssp. smithii are described as new.     

Chromosomal phylogeny of certain shrews of the genera Crocidura and Suncus (Insectivora)

High-resolution chromosome analysis of eight Palaearctic and Oriental species of white-toothed shrews reveals almost complete chromosomal homology between the karyotypes studied, and extensive G-band homology is demonstrated even between species of the genera Crocidura and Suncus . Robertsonian translocations, tandem fusions, fissions, whole-arm reciprocal translocations, centromeric shifts, heterochromatin additions, and inversions are identified as the main mechanisms of chromosomal evolution. The evolutionary relationships of the Eurasian crocidurines under study are reconstructed and a hypothetical ancestral karyotype with 44 chromosomes is proposed.     

Karyological studies on the Sino-Himalayan genus, Cremanthodiurn (Asteraceae: Senecioneae)

Twenty-two populations of seven species of Cremanthodium from high altitude regions of western China were observed karyologically. C. ellisii, C. microglossum, C. brunneo-pilosum, C. stenoglossum, C. discoideum and C. lineare all had the same chromosome number of 2 n = 58 whereas C. humile had 2 n = 60. All chromosome numbers of these species are documented here for the first time. The basic number of x = 30 is new for this genus. The karyotypes of all species belong to 2A type according to Stebbins' asymmetry classification of karyotypes. Two basic chromosome numbers, x = 30 and x = 29 in Cremanthodium , correspond exactly to two branching patterns in this genus, sympodial versus monopodial. The systematic and taxonomic statuses of the sympodial species need further study. The karyomorphological data provide no support to the sectional subdivision in Cremanthodium .     

Cytological studies inCyclamen subg.Cyclamen (Primulaceae)

Although theCyclamen subg.Cyclamen spp. are morphologically variable, previous studies suggest a superficial cytological uniformity. New chromosome numbers and an indication of karyotypic instability are reported inC. hederifolium andC. africanum that reveal that the cytology of the subgenus is more complicated than previous accounts suggest. The possible significance of these phenomena is discussed. The diploid status ofC. purpurascens has been confirmed and a distinction between the three diploid karyotypes has been described. The cytological variation may help to explain the well documented morphological variation exhibited in these species.     

喜马拉雅-横断山区钟花报春居群遗传多样性及遗传分化

应用简单序列重复区间(ISSR,Inter-simple sequence repeat)分子标记,对喜马拉雅．横断山区钟花报春(Primula sikkimensis)进行居群遗传分析。用10个ISSR引物对13个居群的254个个体进行扩增,共检出91条扩增片段,全部为多态带,总的多态位点百分率为100％。Shannon多样性指数(Ho)从0．2293到0．4016,居群水平上平均值(HPCP)为0．3211,物种水平上(Hsp)为0．5576。利用分子方差(AMOVA)软件分析,其结果为：在总的遗传变异中,有50．28％的遗传变异属于居群之间;用POPGENE计算出的遗传分化系数GST=0．4127,即居群间的分化变异占居群总遗传变异的41．27％,比AMOVA分析所得的结果偏低。居群间遗传距离变化范围从0．0780到0．4748,遗传一致度(I)的变化范围从0．6220到0．9250。居群间的基因流Nm=0．7114,相对低的基因流可能是维持钟花报春居群遗传分化的原因。这表明,喜马拉雅．横断山区钟花报春的13个居群具有很高的遗传多样性,并且居群间的分化也很大。     

中国-喜马拉雅植物亚区特有物种江孜乌头的分类学订正

中国-喜马拉雅植物亚区不仅是乌头属植物地理分布的频度中心、多样性中心,原始类群的保存中心、分化中心,而且是特有类群的分布中心。作为该亚区特有物种之一的江孜乌头(Aconitum ludlowii Exell),是Arthur Wallis Exell于1926年根据采自我国西藏江孜的标本发表的新种。其繁殖器官特征及地理分布特点均与原始文献记载(狭域种)不尽一致。为此,对其做分类学修订。该研究应用经典植物分类学方法,进行野外考察、标本采集与鉴定,查阅中国科学院植物研究所植物标本馆(PE)的相关标本并进行形态学观察比较。结果表明:该物种不同标本心皮从无毛、近无毛至被毛,呈现一连续过渡情况。因此,考虑将心皮被毛一类不作为新分类群处理,只在以上研究基础上,做如下修订:心皮5,无毛或上部被毛,西藏拉萨、山南地区、那曲地区及日喀则地区均有分布。该研究结果可为国产乌头属植物的整理以及江孜乌头遗传多样性分析和物种保护提供基础资料。     

Multivariate studies of Ipheion (Amaryllidaceae, Allioideae) and related genera

Ipheion, as recognized by Guaglianone (Darwiniana 17:159–242, 1972), is a small genus of the family Amaryllidaceae, subfamily Allioideae, tribe Gilliesieae endemic to South America. Since 1800, the species of Ipheion were treated under Beauverdia, Brodiaea, Milla, Nothoscordum, Tristagma or Triteleia. Nowadays, some species of Ipheion are treated as Tristagma and some other under Nothoscordum. In this paper, we analyzed the morphological variation among species of Ipheion and related genera using a numerical taxonomic approach based on overall similarity, to investigate the intergeneric and infrageneric variations to the circumscribed groups. Based on 141 operational taxonomic units and 51 morphological characters, multivariate analyses were performed. Results showed that Ipheion separated into two groups according to Guaglianone’s sectional treatment: Ipheion sect. Ipheion is morphologically more similar to the studied species of Tristagma, while I. sect. Hirtellum can be separated from Nothoscordum/Zoellnerallium and from Tristagma and allies. These a priori groupings were tested using discriminant and univariate analyses. Diagnostic characters were selected to differentiate groups. Previous taxonomic treatments are discussed and results are also evaluated using additional karyological and geographical data.     

A new species of Aethionema (Brassicaceae) from the Bulgarian flora

Aethionema rhodopaeum D. Pavlova is described as a new species from the eastern Rhodope Mountains. The plant was found growing only on serpentines, in two localities, at an altitude of approximately 400 m. The localities are typical open habitats with sparsely colonized debris. The plant communities, composed mainly of xerophytes with a mosaic distribution, contain a large number of rare and endemic species for the Bulgarian flora. The new species belongs to the Aethionema saxatile group and is quite close to the species A. saxatile (L.) R. Br., in particular to ssp. creticum and ssp. graecum . The following diagnostic features are given for the new species: inner filament length always greater than half the petal length, lack of teeth of the filaments, longer [2–3(3.5) mm] style than that of A. saxatile subspecies, and dark purple petals. All leaves are broadly elliptical to suborbicular, obtuse, and fleshy. The chromosome number of the new species is 2 n  = 24. The differences between the new species and related taxa are also discussed.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 155 , 533–540.     

Hybridization and Rorippa austriaca (Brassicaceae) invasion in Germany

Introgressive hybridization between the invasive Rorippa austriaca and the native R. sylvestris in Germany has been studied using chloroplast DNA (trnL intron) and amplified fragment length polymorphism. Three hybrid zones between the invasive and native species were located in the Ruhr Valley (Mülheim) and at the River Main near Würzburg (Randersacker, Winterhausen). In each hybrid zone hybridization was indicated by additivity of region-specific amplified fragment length polymorphism markers proving independent hybridization events. The hybrids were either morphologically intermediate (R. x armoracioides) or were close to R. sylvestris. The trnL intron of R. austriaca is characterized by a species-specific deletion. This diagnostic chloroplast marker of R. austriaca was detected in three individuals of R. sylvestris providing evidence for introgression of the invasive chloroplast into the native species. Bidirectional introgression of R. austriaca markers into R. sylvestris and of R. sylvestris markers into R. austriaca was detected in the amplified fragment length polymorphism analysis. Some of the invasive R. austriaca populations showed high within-population variation. A possible association among introgression, within-population variation and invasion success is discussed. The morphologically intermediate hybrid R. x armoracioides is currently spreading in northern Germany. It forms large populations without its parent species R. austriaca and R. sylvestris. It is concluded that hybridization between invasive R. austriaca and native R. sylvestris may lead to the evolution of a new invasive species R. x armoracioides.     

Genetic differentiation in endemic Lobularia (Brassicaceae) in the Canary Islands

Patterns of genetic diversity were examined in five endemic subspecies of the Lobularia canariensis complex from six of the Canary Islands. The taxa are interfertile, insect-pollinated outbreeders with wind dispersal. Electrophoretic analysis revealed a high level of genetic polymorphism at ten loci coding soluble enzymes, with a mean of 2.38 alleles per locus, 73.7 % polymorphic loci, and a mean heterozygosity of 0.279. Excesses of homozygotes, indicating inbreeding, were observed in small populations. The average total diversity was high, F.,=0.518. Among-population diversity, F_ST=0.318, contributed more to the total diversity than within-population diversity, F_IS=0.222. Little geographic or taxonomic patterning of the allozyme variation was observed. The mean genetic identitity for pairwise comparisons of the 19 populations was 0.76, with a range of 0.51–0.96 and c. 17 % of the comparisons below 0.67 and c. 8 % above 0.90. The results contrast with the many cases of high genetic identities reported for populations of endemic plants on oceanic islands. High levels of allozyme divergence suggest a relatively old origin of the L. canariensis complex and a long period of isolation of some of the populations.     

Interspecific hybridization in Rorippa (Brassicaceae): Patterns and processes

The current knowledge on natural hybridization between European lowland Rorippa species is reviewed. Morphological, cytological and molecular markers provide substantial evidence that four Rorippa species (R. amphibia, R. austriaca, R. palustris and R. sylvestris) are involved in hybridization processes. The main factors promoting initial hybridization events between Rorippa species in Europe are (1) natural and anthropogenic habitat disturbance, (2) the invasion of non‐native R. austriaca into western central Europe and (3) the self‐incompatibility system of R. amphibia, R. austriaca and R. sylvestris coupled with clonal growth. Outcomes of hybridization between European Rorippa species show a broad range from incidental hybrids through the formation of hybrid swarms to the evolution of new hybrid taxa. Rorippa × armoracioides is certainly the most successful Rorippa hybrid. It results from hybridization between R. austriaca and R. sylvestris and is known from many localities in the native range of R. austriaca and in regions invaded by R. austriaca. Within this system hybrid zones of different age provide the rare opportunity to analyse different stages of hybrid formation and hybrid speciation in natural populations.