刺儿菜复合体的形态学研究

本文对不同产地,不同居群的全国２００份刺儿菜复合体标本的若干性状选用Ｅ．Ａｎｄｅｒｓｏｎ的形象化散点图和柱状图方法进行研究分析,认为将大刺儿菜与小刺儿菜分为独立的种是合理的。     

蓟属两种植物的染色体研究

本文对蓟属（Ｃｉｒｓｉｕｍ）的两个形态相似的近缘种大刺儿菜和小刺儿菜进行了染色体研究,其中后者为首次报道。观察结果表明：两个种的染色体数目均为２ｎ＝２ｘ＝３４：它们的核型是：大刺儿菜．２ｎ＝２ｘ＝３４＝２０ｍ＋１２ｓｍ＋２ｓｔ：小刺儿菜．２ｎ＝２ｘ＝３４＝２２ｍ＋１０ｋｍ（２ＳＡＴ）＋２ｓｔ。通过核型比较,认为它们是两个独立的种．而且后者比前者进化。     

蓟属二种植物过氧化物同工酶的酶谱式样及其分类学意义

采用聚丙烯酰胺凝胶电泳的方法对蓟属的两个近缘种：大刺儿菜和小刺儿菜的过氧化物酶同工酶分别在不同的发育阶段和不同的生长下进行了比较研究。结果表明,二者的酶谱存在 明显的差异,从而支持将它们作为两个的种对待。此外,本文还对ＰＯＸ酶谱的分类学意义进行了探讨。     

盘鮈属鱼类口吸盘的形态分化及其意义

本文从研究盘鮈属鱼类口吸盘的形态结构入手,探讨它们口吸盘结构分化的进化意义和生物学意义。具大、小吸盘的两个类群是盘鮈鱼类在演化进程中分化成的两个自然类群,它们为适应不同的栖息环境,吸盘的微观结构和须的长短等进一步分化,分化途径在两个类群各不相同。     

基于数字化标本和种群形态变异特征试论块茎堇菜的分类地位

块茎堇菜是青藏高原及其邻近地区的一种特有两型闭花植物,目前其分类地位存在诸多争议。据此,本文对块茎堇菜及其近缘类群鳞茎堇菜的主要数字化标本以及同域分布的几个自然种群的叶片形态变异特征进行了分析。结果显示,所有参试数字化标本被分为两个明显不同的集群,一个集群符合块茎堇菜的叶片形态,另一集群则符合鳞茎堇菜;同样,同域分布的6个自然种群也分为两个集群。此外,叶片形态变异分析还显示叶片先端和叶基部形态参数ΔW、AL、BL和LWR在块茎堇菜/鳞茎堇菜同一类群不同种群间或种群内变异幅度较小且较为稳定,然而它们在不同类群间差异却极为显著（P<0.01）。因此,块茎堇菜和鳞茎堇菜理应作为两个不同的类群处理,这也表明叶片形态特征完全可以作为鳞茎堇菜和块茎堇菜的重要分类学依据。     

盘Ju属鱼类口吸盘的形态分化及其意义

本文从研究盘Ｊｕ属鱼类口吸盘的形态结构入手,探讨它们口吸盘结构分化的进化意义和生物学意义。具大,小吸盘的两个类群是盘Ｊｕ鱼类的演化进程中分化优的两个自然类群,它们为适应不同的栖息环境,吸盘的微观结构和须的长短等进一步分化,分化途径在两个类群各不相同。     

江孜沙棘和云南沙棘之间谱系分化和亲缘地理

研究具有邻近分布的近缘类群的遗传分化和谱系筛选对于进一步揭示物种形成机制具有重要意义。该文以沙棘属(Hippophae)临域分布的两个类群, 江孜沙棘(H. gyantsensis)和云南沙棘(H. rhamnoides subsp. yunnanensis)为研究对象, 进行群体水平上的母系分化研究。前一个种分布于西藏的中西部, 而后者主要分布于青藏高原东南部的云南西北部、四川西部和西藏东南部。两个类群在叶和果实性状存在明显区别。叶绿体在沙棘属植物中为母系遗传。共研究了两个类群14种群109个沙棘个体的叶绿体trnL-F、trnS-G序列; 序列排序后共发现11种单倍型, 江孜沙棘和云南沙棘分别有7种和6种, 两种单倍型为两个类群共享。分支分析和嵌套进化分析进一步表明, 两个类群之间的单倍型相互交错, 单倍型分化与形态上划分的两个类群不一致, 表明它们之间具有十分复杂的谱系筛选过程。这些发现明显不支持以前提出的有关江孜沙棘系统位置的假设。但是, 目前所获得的证据不能区分该物种究竟是通过异域分化还是同倍性杂交起源的。不同种群固定特有单倍型表明, 两个类群都在最后一次冰期可能存在多个避难所。     

香蕉炭疽菌菌株亲缘关系的RAPD分析*

应用筛选的8个Operon随机引物对供试菌株的DNA进行扩增,所产生的RAPD图谱揭示了香蕉炭疽菌具有丰富的种内遗传多样性。UPGMA聚类分析的结果表明：26个香蕉炭疽菌被分为两个与地理来源相关的RAPD聚类群,它们分别由广东菌株和海南菌株为主组成。在两个香蕉菌群的外侧,两个胶胞炭疽菌菌株聚为一个小的外群。这些结果表明香蕉炭疽菌存在有与地域相关的种下类群分化。     

香蕉炭疽菌菌株亲缘关系的RAPD分析

应用筛选的8个Operon随机引物对供试菌株的DNA进行扩增,所产生的RAPD图谱揭示了香蕉炭疽菌具有丰富的种内遗传多样性。UPGMA聚类分析的结果表明：26个香蕉炭疽菌被分为两个与地理来源相关的RAPD聚类群,它们分别由广东菌株和海南菌株为主组成。在两个香蕉菌群的外侧,两个胶胞炭疽菌菌株聚为一个小的外群。这些结果表明香蕉炭疽菌存在有与地域相关的种下类群分化。     

国产粟米草属的分类研究

本文根据国产粟米草属Mollugo L.8种植物的外部形态的5个分类学特征,尤其是种子形态结构的演化特征,认为该属植物种中实际存在着两个自然类群,特将该属中种子具有假种皮和种阜的、即星粟草属Glinus L.在我国予以恢复,它是一个较粟米草属原始的自然类群。     

A phylogenetic study of the generic relationships within the subtribe Leucophoropterina Schuh (Miridae: Phylinae: Leucophoropterini)

The subtribe Leucophoropterina (Miridae: Phylinae: Leucophoropterini) is a relatively small lineage of mirids comprising 23 genera and 104 species. Most of the species are endemic to the Indo‐Pacific and Australia, and many are considered ant mimics. A phylogenetic analysis including both the Australian and the Indo‐Pacific taxa was conducted for the first time with a dataset of 137 morphological characters coded for all but two known species of Leucophoropterina. The hypothesis by Schuh ( 1984 ) of at least two major lineages of ant‐mimicking taxa based on his analysis of the Indo‐Pacific taxa continues to be supported with our inclusion of Australian taxa. The Australian taxa and Indo‐Pacific taxa of Leucophoropterina do not form independent, geographically based lineages, but instead comprise several lineages containing taxa from both regions. This study provides a basis for future detailed studies of biogeography and ant mimicry in the group.     

ON SPECIES and OTHER TAXA

Abstract— It is argued that taxa, whether Linnaean or phylogenetic, belong to Popper's worlds 2 and 3, the worlds of knowledge, but that they represent entities residing in world 1, the world of objects, namely, classes of living beings. The Linnaean taxa are concepts, and thus untestable, whereas phylogenetic taxa are statements, the monophyletic taxa being true, and the paraphyletic and polyphyletic ones false statements. The taxa are neither strictly nor numerically universal statements, but probabilistic ones which cannot be falsified by single observations. It is suggested that the classical "species problem" is due to the fact that "species" has been used in three different senses. First, traditionally it has been assumed that the specific "essence" of an organism is that by which it is what it is. When we know the species, we know the organism. Second, the species are terminal taxa in the phylogenetic hierarchy. This implies that it is only a very small part of the "essence" of the organism which distinguishes the species. The remaining part characterizes the succession of superior taxa in the phylogenetic lineage which ends with the species in question. Third, the species has been regarded to be the "evolutionary unit." This idea may be refuted for two reasons: (1) since concepts and statements cannot evolve, species cannot evolve either, and (2) it is generally in very small isolated populations that evolutionary innovations are first established. In Linnean systematics the superior taxa are allotted categorical rank. The fact that the classification is constrained by this conventional stipulation implies that the superior taxa are often man-made artifacts. In the phylogenetic hierarchy, composed of monophyletic taxa, the ontological states of the taxa is completely independent of their numerical rank; the kingdom is as "real" as the species.     

Shortcuts in biodiversity research: What determines the performance of higher taxa as surrogates for species?

Biodiversity research is often impeded by the time and resources required to identify species. One possible solution is to use higher taxa to predict species richness and community composition. However, previous studies have shown that the performance of higher taxa as surrogates for species is highly variable, making it difficult to predict whether the method will be reliable for a particular objective. Using 8 independent datasets, I tested whether higher taxa accurately characterize the responses of beetle and ant communities to environmental drivers. For each dataset, ordinations were carried out using species and higher taxa, and the two compared using the Procrustes m² statistic (a scale‐independent variant of Procrustes sum of squares). I then modelled the relationship between five hypothesised explanatory variables and 1) Procrustes m², and 2) the coefficient of determination (R²) for the correlation between richness of species and higher taxa. The species to higher taxon ratio, community structure, beta diversity, completeness of sampling, and taxon (beetles or ants) were all significant predictors of m², together explaining 88% of the variance. The only significant predictor of R² was the species to higher taxon ratio, which explained 45% of the variance. When using higher taxa to predict community composition, better performance is expected when the ratio of species to higher taxa is low, in communities with high evenness and high species turnover, and when there is niche conservation within higher taxa. When using higher taxa to predict species richness, effective surrogacy can be expected when the species to higher taxon ratio is very low. When it is not, surrogacy performance may be strongly influenced by stochastic factors, making predictions of performance difficult.     

Molecular phylogenetics and historical biogeography of Hawaiian Dryopteris (Dryopteridaceae)

The fern genus Dryopteris (Dryopteridaceae) is represented in the Hawaiian Islands by 18 endemic taxa and one non-endemic, native species. The goals of this study were to determine whether Dryopteris in Hawai'i is monophyletic and to infer the biogeographical origins of Hawaiian Dryopteris by determining the geographical distributions of their closest living relatives. We sequenced two chloroplast DNA fragments, rbcL and the trnL-F intergenic spacer (IGS), for 18 Hawaiian taxa, 45 non-Hawaiian taxa, and two outgroup species. For individual fragments, we estimated phylogenetic relationships using Bayesian inference and maximum parsimony. We performed a combined analysis of both cpDNA fragments employing Bayesian inference, maximum parsimony, and maximum likelihood. These analyses indicate that Hawaiian Dryopteris is not monophyletic, and that there were at least five separate colonizations of the Hawaiian Islands by different species of dryopteroid ferns, with most of the five groups having closest relatives in SE Asia. The results suggest that one colonizing ancestor, perhaps from SE Asia, gave rise to eight endemic taxa (the glabra group). Another colonizing ancestor, also possibly from SE Asia, gave rise to a group of five endemic taxa (the exindusiate group). Dryopteris fusco-atra and its two varieties, which are endemic to Hawai'i, most likely diversified from a SE Asian ancestor. The Hawaiian endemic Nothoperanema rubiginosum has its closest relatives in SE Asia, and while the remaining two species, D. wallichiana and D. subbipinnata, are sister species, their biogeographical origins could not be determined from these analyses due to the widespread distributions of D. wallichiana and its closest non-Hawaiian relative.     

Electrophoretic delineation of species boundaries within the short-necked freshwater turtles of Australia (Testudines: Ghelidae)

A total of 222 specimens from 55 populations of short-necked chelid turtle was collected from drainages in Australia and Papua New Guinea. Two populations were initially considered to belong to different diagnosable taxa if all individuals in one population could be distinguished from all individuals in the other by fixed allozyme differences. When two populations or diagnosable taxa shared allozymes at all presumptive loci, their profiles were combined into a single diagnosable taxon. Comparisons between populations and emerging diagnosable taxa were repeated until no further changes were possible. The species Elseya dentata comprised five clearly diagnosable taxa, differing by between 4 and 19 fixed allozyme differences. The currently recognized El. latisternum and El. novaeguineae were each a single diagnosable taxon, and there were three diagnosable taxa, including a sibling pair, that could not be assigned to a currendy described Elseya species. In contrast, all forms of Emydura were very closely related, with no two taxa differing by more than three fixed allozyme differences. There were three diagnosable taxa in the north (Em. victoriae, Em. subglobosa and one new form), though support for them was marginal. In the south, Em. macquarii, Em. krefflii and Em. signata formed only a single diagnosable taxon, even sharing rare alleles. If the phylogenetic species concept is adopted, there is support for recognition of 16 species of short-necked turtle in Australia, including Pseudemydura umbrina. Currendy only 10 are described. Our data also provide evidence of reproductive isolation in some cases (sympatric or parapatric), and comparative evidence (sensu Mayr) in others, than the traditional biological species concept applies also to these diagnosable taxa.     

Biodiversity surrogacy: indicator taxa as predictors of total species richness in Brazilian Atlantic forest and Caatinga

The use of indicator taxa as biodiversity surrogates has received widespread attention in conservation planning, but remains a highly contentious issue. Here we assess biodiversity surrogacy in the two most important biomes of tropical northeastern Brazil, Atlantic forest and Caatinga. We examine the extent to which species richness is correlated among taxonomic groups, and assess relationships between the richness of individual groups, and combinations of groups and total species richness. We introduce a new approach to dealing with autocorrelation between focal taxon richness and total species richness, using standardized data such that each taxon is given equal weight. Our Atlantic forest data covered seven taxa (bryophytes, pteridophytes, trees, ants, euglosine bees, birds, and mammals; total of 768 species) sampled from 12 sites; in Caatinga it was four taxa (trees, spiders, beetles and ants; total of 184 species) from 25 sites. Our results showed that: (1) in nearly all cases the species richnesses of individual taxa were significantly correlated with each other; (2) the species richnesses of most individual taxa were significantly correlated with total species richness in both biomes; (3) only two taxa were required for excellent (R ² > 80%) surrogacy of total species richness in both biomes; and (4) the same two taxa (trees and ants) can provide reasonable (R ² > 60%) surrogacy for total richness in these contrasting biomes. Our findings therefore suggest that the ‘shopping basket of taxa’ required for effective biodiversity surrogacy may not only need to be very small (two taxa), but may also be very limited in composition.     

A revision of the Afrotropical taxa of the genus Amerila Walker (Lepidoptera: Arctiidae)

This paper comprises a complete revision of the Afrotropical species of the genus Amerila ( Rhodogastria auct.), based on adult morphology. Examination of type material for most described taxa has resulted in numerous taxonomic changes. From a total of forty-seven previously described African taxa, thirty-five species including five newly described species and two new subspecies are recognized. For ten taxa, lectotypes have been selected, and for one species a neotype had to be designated. For each species, in addition to synonymy, a brief diagnosis based on external characters and genitalia is given, and the known distribution summarized. All species are illustrated by photographs and illustrations of male genitalia (except A.rufifemur , the male of which is unknown), and a key for determination of males by external characters is provided.     

Ecology of a steppe-tundra gradient in interior Alaska

Abstract. Subarctic steppe is currently restricted in interior Alaska and the Yukon Territory to steep, south-facing river bluffs. Paleoecological and biogeographic evidence suggests that some steppe taxa may have been more widespread during the Full-Glacial. We examined factors controlling the distribution of steppe taxa on an elevation gradient across a steppetundra ecotone; such analyses may help define potential Full-Glacial distributions of these taxa. Multivariate analyses suggest that species can be divided into four spatially distinct groups, but individualistic species distributions create considerable overlap among these groups. The steppe-tundra ecotone comprises a broad zone of mixing between steppe taxa and drought-tolerant alpine tundra taxa, followed by an abrupt shift to alpine shrub tundra. The transition from low steppe to tundra vegetation is primarily associated with a gradient of decreasing soil temperature. The more abrupt transition from mixed steppe-tundra to alpine shrub tundra vegetation is primarily associated with changes in soil depth and soil moisture. Variation in vegetation within steppe is associated with gradients in soil phosphorus and moisture. Greenhouse experiments on drought tolerance of two steppe and two tundra taxa suggest that the individualistic distribution of species along the ecotone is partly a function of physiological differences among species. Our analyses of vegetation-environment relationships support the hypothesis that some components of the steppe community could have been more widespread during the colder Full-Glacial.