Morphological and genetic analysis of fish of a Carassius complex (Cyprinidae) in Lake Kasumigaura with reference to the taxonomic status of two all-female triploid morphs

The classification of the Carassius complex (Cyprinidae) including all-female triploids, called ginbuna in Japanese, is so confused that three sympatric morphs of crucian carp in Lake Kasumigaura are categorized into two different subspecies within a species. We examined them in order to explain the coexistence of more than one subspecies and determine the founder of the triploid lineages in the crucian carp fauna in the lake. Principal component analysis proved that the three sympatric morphs had a morphometric basis distinguishable from each other. Ploidy was determined by flow cytometry which showed triploids in two morphs and diploids in the other morph. Stepwise discriminant analysis using only meristic characteristics could separate the diploids from the triploids. Phylogenetic analysis using mitochondrial DNA inferred two lineages in which one was composed of a triploid morph and the other was a diploid–triploid mixture. Disagreement between the taxonomic status and the phylogenetic status is explicable by assuming that the triploids in the Carassius complex had independent origins leading to the different subspecies. C. auratus langsdorfii appears to show genetic complexities that traditional taxonomic classification can not unravel.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 79 , 351–357.     

Evolution along the Great Rift Valley: phenotypic and genetic differentiation of East African white‐eyes (Aves,Zosteropidae)

The moist and cool cloud forests of East Africa represent a network of isolated habitats that are separated by dry and warm lowland savannah, offering an opportunity to investigate how strikingly different selective regimes affect species diversification. Here, we used the passerine genus Zosterops (white‐eyes) from this region as our model system. Species of the genus occur in contrasting distribution settings, with geographical mountain isolation driving diversification, and savannah interconnectivity preventing differentiation. We analyze (1) patterns of phenotypic and genetic differentiation in high‐ and lowland species (different distribution settings), (2) investigate the potential effects of natural selection and temporal and spatial isolation (evolutionary drivers), and (3) critically review the taxonomy of this species complex. We found strong phenotypic and genetic differentiation among and within the three focal species, both in the highland species complex and in the lowland taxa. Altitude was a stronger predictor of phenotypic patterns than the current taxonomic classification. We found longitudinal and latitudinal phenotypic gradients for all three species. Furthermore, wing length and body weight were significantly correlated with altitude and habitat type in the highland species Z. poliogaster. Genetic and phenotypic divergence showed contrasting inter‐ and intraspecific structures. We suggest that the evolution of phenotypic characters is mainly driven by natural selection due to differences in the two macro‐habitats, cloud forest and savannah. In contrast, patterns of neutral genetic variation appear to be rather driven by geographical isolation of the respective mountain massifs. Populations of the Z. poliogaster complex, as well as Z. senegalensis and Z. abyssinicus, are not monophyletic based on microsatellite data and have higher levels of intraspecific differentiation compared to the currently accepted species.     

粒毛盘菌属种间关系的分子系统学初探*

粒毛盘菌属包括晶杯菌科中子囊盘表面具有毛状物,毛状物全表面具有颗粒状纹饰以及外囊盘被结构为矩胞组织的部分种类,种间形态解剖结构多样,研究采用ITS15.8S rDNAITS2序列分析的方法探讨该属种间的系统发育关系。在供试的粒毛盘菌15个分类单元中,14个以89%的支持强度值相聚在一起,其中Lachnum clandestinum与 L. fuscescens关系最近,其支持强度值为100%;其次为L. controversum 与L. spartinae,其支持强度值为97%;而姊妹群L. euterpes,L. pteridophyllum,L. singerianum和L. lushanense彼此关系较远,其支持强度值均小于50%;L. sclerotii位于系统发育树的最外侧,为供试15个分类单元中距离最远的一个,结果表明粒毛盘菌属可能是多起源的。     

Phylogenetic relationships between parthenogens and their sexual relatives: the possible routes to parthenogenesis in animals

In theory, parthenogenetic lineages have low evolutionary potential because they inexorably accumulate deleterious mutations and do not generate much genotypic diversity. As a result, most parthenogenetic taxa occupy the terminal nodes of phylogenetic trees. The rate and mode of development of parthenogenesis are important factors to consider when assessing its costs and benefits since they determine both the level of genetic diversity and the ecological adaptability of the resulting lineages. The origin of parthenogenesis is polyphyletic in many taxa, suggesting that genetic systems maintaining sexuality are often labile. In addition, the loss of sex may be achieved in several ways, leading to parthenogenetic lineages with distinct genetic profiles. This could then influence not only the fate of such lineages in the long term, but also the outcome of competition with their sexual counterparts in the short term. In this paper, we review the possible evolutionary routes to parthenogenesis based on a survey of the phylogenetic relationships between sexual and parthenogenetic lineages in a broad range of animals. We also examine the different mechanisms by which parthenogenetic lineages could arise, and discuss the influence of these mechanisms on both the genetic properties and the ecological life styles of the resulting lineages.  © 2003 The Linnean Society of London. Biological Journal of the Linnean Society , 2003, 79 , 151–163.     

Morphological and cytological evidence for polyphyletic allopolyploidy inArctostaphylos mewukka (Ericaceae)

The central Sierran tetraploidArctostaphylos mewukka Merriam has been reported to be an allopolyploid originating from the diploid species,A. patula Greene and eitherA. viscida subsp.viscida Parry orA. viscida subsp.mariposa (Dudley)P. V. Wells, although without conclusive evidence. Morphometrics and the verification and determination of chromosome numbers were used to substantiate the evolutionary relationships among these species. A closely related species,Arctostaphylos truei Knight, was also examined using these methods to determine its separability fromA. mewukka. The morphometric analyses support a hypothesis for a polyphyletic origin ofA. mewukka from different races ofA. viscida andA. patula. The chromosomal data, although inclusive, also support this hypothesis. The data do not support the recognition ofA. truei as a taxonomic entity separate fromA. mewukka at the species level.     

Evolutionary history of asexual hybrid loaches (Cobitis: Teleostei) inferred from phylogenetic analysis of mitochondrial DNA variation

Reconstruction of the evolutionary history of asexual lineages undermines their suitability as models for the studies of evolutionary consequences of sexual reproduction. Using molecular tools we addressed the origin, age and maternal ancestry of diploid and triploid asexual lineages arisen through the hybridization between spiny loaches Cobitis elongatoides, C. taenia and C. tanaitica. Reconstructions of the phylogenetic relationships among mitochondrial DNA (mtDNA) haplotypes, revealed by sequence analyses, suggest that both hybrid complexes (C. elongatoides-taenia and C. elongatoides-tanaitica) contained several asexual lineages of independent origin. Cobitis elongatoides was the exclusive maternal ancestor of all the C. elongatoides-tanaitica hybrids, whereas within the C. elongatoides-taenia complex, hybridization was reciprocal. In both complexes the low haplotype divergences were consistent with a recent origin of asexual lineages. Combined mtDNA and allozyme data suggest that the triploids arose through the incorporation of a haploid sperm genome into unreduced ova produced by diploid hybrids.     

雪鸡属分类地位探讨

以5种鸡形目鸟类,包括4个藏雪鸡Tetraogallus tibetanus、12个喜玛拉雅雪鸡T.himalayensis、1个阿尔泰雪鸡T.altaicus、1个石鸡Alectoris chuckar和1个斑翅山鹑Perdix dauurica为材料.通过P(永扩增线粒体细胞色素6基因513个碱基,同时从GenBank下载25种鸡形目鸟类细胞色素b基因序列.通过对鸡形目24个属线粒体细胞色素b基因序列的分析,结果表明共有214个变异位点,简约信息位点184个.以鸿雁 Anser cygnoides为外群,在运用不同分析方法得到的拓扑结构基础上,构建了最大简约树(MP)和最大似然树(ML),结果表明鸡形目鸟类鹑族和雉族基本上是多系发生的.结合分子钟和遗传信息分析,可以得出雪鸡属在鹑族中形成的时间相对较晚,约在14.6Myr出现石鸡属的祖先种群;而在约12.6Myr属和鹌鹑属开始出现.雪鸡属的祖先足起源于低海拔环境,后来伴随着青藏高原的逐渐降起和更新世冰期事件的发生各自演化形成现今各个种.     

Morphogenesis of rissoidae in the inland basins of the Eastern Paratethys

Miocene rissoids from the heterochronous low-salinity seas of the Eastern Paratethys (Early Chokrakian, Karaganian, Late Konkian, Early Sarmatian, and Early Maeotian) were revised. The polyphyletic genus Mohrensternia is subdivided into several generic and subgeneric taxa. The new genus Zhgentia and the new subgenera Rissoa (Turboellina), R. (Pseudoturboellina), and R. (Maeotia) are established.     

Recent mathematical approaches to reconstruct phylogenies: A chemosystematist's and botanist's view

Some basic problems of mathematical phylogenetics are discussed. While algorithms regularly depend on the principle of parsimony, some features of phylogenesis interfere with that principle. Nonrandomness of the distribution of mutations as well as the inconstancy of the molecular clock in time and within a given sequence can bias the calculated relationships of closely related taxa. True comparability of sequences is difficult to establish, since this requires defining of homology of positions and of functions of amino acids as well. Parallelism and convergence can give rise to errors in establishing homology. Furthermore, they are difficult to be integrated into a consistent mathematical approach. The asymmetry of identity versus difference matrices is discussed. Common mathematical procedures implicate the monophyletic hypothesis as well as strict dichotomy of the final tree. Real phylogeny demands to introduce more flexible approaches with respect to monophyly and dichotomy. Graph theory offers the possibility to prove the minimality of a given tree and to develop more flexible approaches. The consequences of altering the procedures to compare sequences can be tested. This is demonstrated by calculations with a set of 15 cytochromes from various taxa. To interpret a calculated tree requires a sharp distinction between taxonomy and phyletics. This is exemplified for the case of directly linked taxa. The limits of resolving uncertain relationships by accumulating more data are mentioned.This paper was partly presented at the Symposium Theory and practice of botanical classification, during the 14th International Botanical Congress, Berlin, July 1987.     

基于28S rDNA序列构建侧耳属系统发育树

通过对侧耳属18个分类单元的28S rDNA序列进行分析,构建了侧耳属较为完整的系统发育树。分子系统学资料显示:Coremiopleurotus组和侧耳属内单、二系菌丝系统分别为多系起源的;Pleurotus组单系菌丝种类、被划分在Tuberregium组的具核侧耳和Lentodiellum组的P. levis能够分别与侧耳属内其他成员进行区分;红侧耳、P. calyptratus、P. opuntiae三者关系密切,而金顶侧耳应作为白黄侧耳的种下分类单元。