Character diversity and taxonomic weighting in the numerical taxonomy of two insect groups (Hemiptera: Diaspididae, and Lepidoptera: Drepanidae)

Abstract Methods used to assess ecological diversity have been adapted to show that binary and multistate taxonomic characters may be assigned measures of diversity that correspond closely with their information content. A distinction is drawn between the two major components of character diversity, corresponding respectively to the number of states exhibited and the evenness with which these are distributed over taxa. By choosing characters with high heterogeneity (i.e. high values of those indices which combine the two components of diversity) it is possible to select relatively small subsets of characters which effectively reproduce the main features of reference ordinations of the taxa which were based on all available characters. Such diversity indices and the appropriate measures of information content can be regarded as a system of weights which vary ten-fold or more among themselves and which can be applied to all the characters to produce numerically weighted ordinations. Despite the considerable differential weighting introduced in this way, the resulting ordiantions differ very little from 'unweighted' reference ordinations in which all characters have been accorded equal weights. The results suggest that numerical weighting of this kind does little to improve the quality of phenetic procedures when applied to reasonably large bodies of real taxonomic data.     

THE QUANTIFICATION OF SOME PLANT-TAXA CIRCUMSCRIPTIONS

Intrataxon variability is estimated by the technique of numerical taxonomy. Taxa which had been determined by orthodox taxonomic methods are subjected to analyses by numerical phenetics. Comparisons are made of the amounts of cohesion among the members of different taxa in the Bromeliaceae at several taxonomic levels by computing the degrees of similarities between members of the same taxon and of different taxa. Results of these comparisons with several taxa reveal that the variability of a taxon in terms of phenetic distance computed with a large number of characters does not necessarily agree with a subjective appraisal of variability. The method facilitated difficult taxonomic determinations and provided an estimate of the relative evolutionary ages of different taxonomic groups.     

The Beothukis/Culmofrons problem and its bearing on Ediacaran macrofossil taxonomy: evidence from an exceptional new fossil locality

The late Ediacaran siliciclastic successions of eastern Newfoundland, Canada, are renowned for their fossils of soft‐bodied macro‐organisms, which may include some of the earliest animals. Despite the potential importance of such fossils for evolutionary understanding, the taxonomic framework within which Ediacaran macrofossils are described is not clearly defined. Rangeomorphs from a newly discovered fossil surface on the Bonavista Peninsula, Newfoundland, require us to reconsider contemporary use of morphological characters to distinguish between genera and species within Ediacaran taxa. The new surface exhibits remarkable preservational fidelity, resolving features smaller than 0.1 mm in dimension in both frondose and non‐frondose taxa. Such preservation permits the recognition of rarely observed fourth‐ and fifth‐order rangeomorph branching, offering unparalleled opportunities to investigate the fine‐scale construction of rangeomorph taxa including Culmofrons plumosa Laflamme et al., 2012. Our observations enable resolution of taxonomic issues relating to rangeomorphs, specifically overlap between the diagnoses of the frondose genera Beothukis Brasier and Antcliffe, 2009 and Culmofrons. We propose a taxonomic framework for all Ediacaran macrofossils whereby gross architecture, the presence/absence of discrete morphological characters and consideration of growth programme are used to distinguish genera, whereas morphometric or continuous characters define taxa at the species level. On the basis of its morphological characters, Culmofrons plumosa is herein synonymized to a species (Beothukis plumosa comb. nov.) within the genus Beothukis. This discussion emphasizes the need to standardize the taxonomic approach used to describe Ediacaran macrofossil taxa at both the genus and species levels, and raises important considerations for future formulation of higher‐level taxonomic groups.     

Seed protein electrophoresis of some cultivated and wild species of <Emphasis Type="Italic">Chenopodium</Emphasis>

Seed protein profiles of 40 cultivated and wild taxa of Chenopodium have been compared by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The relative similarity between various taxa, estimated by Jaccard’s similarity index and clustered in UPGMA dendrogram, is generally in accordance with taxonomic position, crossability relationships and other biochemical characters. Eight accessions of C. quinoa studied are clustered together and show genetic similarity with closely related C. bushianum and C. berlandieri subsp. nuttalliae. The taxa included under C. album complex are clustered in two groups which show that these taxa are a heterogenous assemblage and their taxonomic affinities need a reassessment. Other wild species studied are placed in the dendrogram more or less according to their taxonomic position.     

Infraspecific variation in Cerastium alpinum s. lat. (Caryophyllaceae) in Central Norway

Within Cerastium alpinum s. lat., several taxa have been circumscribed. Three infraspecific taxa are currently recognized in Nordic literature, but the opinions have varied about their taxonomic levels and relations to each other. Populations of these three taxa — alpinum, glabratum and lanatum — were investigated in Central Norway to elucidate taxonomic relationships on a regional scale. Morphometric analyses (PCA ordination) based on two data sets; one with 61 characters, and one without the 35 indumentum characters, gave different results. The former partly support the use of a higher rank for glabratum , but this analysis may put too much weight on indumentum characters. The reduced data set gave a more continuous transition between the three taxa, with no special status for glabratum. Crossing experiments between the taxa indicated full cross compatibility as far as relative seed set was concerned. Finally, vegetation analysis (DCA ordination) indicated that the three taxa have somewhat different ecological demands. This suggests that they, in spite of hybridization abilities, normally are maintained as separate entities due to habitat differences. A delimitation of three infraspecific taxa at the same level within C. alpinum s. lat. is thus supported by this study. Whether these taxa should be treated as subspecies or varieties strongly depends upon the definitions of these categories. Viewed in a wide geographical context, however, the arguments for subspecific rank are strengthened.     

Phylogenetics and the conservation of rare taxa in the Eucalyptus angustissima complex in Western Australia

Effective conservation that preservesevolutionary entities and processes requiresconservation action that is targeted atappropriate taxonomic units. Molecularphylogenetics can contribute to the resolutionof taxonomic uncertainties by defining therelationships between populations and species,and allowing the recognition of taxonomicentities that reflect evolutionary history.Some uncertainty surrounds the status of taxain the Eucalyptus angustissima complex,which includes threatened taxa with restricteddistributions. The phylogenetic relationshipsbetween populations and taxa in the E.angustissima complex were investigated usingnuclear and chloroplast RFLP analysis.Phylogenetic relationships confirmed thegenetic differentiation of two taxa, identifiedspecies level divergence between two taxacurrently recognised at subspecies level, andestablished the identity of a previouslyundetermined population. Phylogeneticrelationships between the taxa were notcongruent with presumed relationships based onmorphological characters alone.     

Some notes on relation between taxon and character in taxonomy (regarding the paper of A.A. Stekol'nikov "A problem of truth...", Zhurnal Obshchei Biologii. 2003.V.64. No 4. P.367-368)

Under brief consideration is the problem of primary or secondary status of the judgments about taxa relative to the judgments about characters in the biological classifications. The following formal definition of taxonomic system (classification) TS is provided: TS = BT[T, C(t), R(t), R(c), R(tc)], where BT is a biological theory constituting content-wise background of the system, T is a set of taxa, C(t) is a set of taxonomic characters, R(t) is a set of relationships among taxa (similarity, kinship, etc.), R(c) is a set of relationships among characters (homology, etc.), and R(tc) is a set of correspondences among taxa and characters. The latter correspondences may be complete or incomplete. At ontological level, there two basical traditions exist in biological systematics regarding R(tc) according to which the biological diversity is patterned either as a set of groups of organisms (taxa) or as a set of their properties (characters). In the first case, taxon is "primary" relative to character (in cladistics); in its opposite, character is "primary" relative to taxon (in scholasticism, classical typology, classical phylogenetics). At epistemological level, incompleteness of the taxon-character correspondence makes classificatory procedure iterative and taxonomic diagnoses context-dependent. The interative nature of classificatory procedure makes the "primary" or "secondary" status of both taxa and characters relative and alternating. This makes it necessary to introduces a kind of uncertainty relation in biological systematics which means impossibility of simultaneous definition of both extensional and intentional parameters of the taxonomic system at each step of classificatory iterations.     

Assessment of available anatomical characters for linking living mammals to fossil taxa in phylogenetic analyses

Analyses of living and fossil taxa are crucial for understanding biodiversity through time. The total evidence method allows living and fossil taxa to be combined in phylogenies, using molecular data for living taxa and morphological data for living and fossil taxa. With this method, substantial overlap of coded anatomical characters among living and fossil taxa is vital for accurately inferring topology. However, although molecular data for living species are widely available, scientists generating morphological data mainly focus on fossils. Therefore, there are fewer coded anatomical characters in living taxa, even in well-studied groups such as mammals. We investigated the number of coded anatomical characters available in phylogenetic matrices for living mammals and how these were phylogenetically distributed across orders. Eleven of 28 mammalian orders have less than 25% species with available characters; this has implications for the accurate placement of fossils, although the issue is less pronounced at higher taxonomic levels. In most orders, species with available characters are randomly distributed across the phylogeny, which may reduce the impact of the problem. We suggest that increased morphological data collection efforts for living taxa are needed to produce accurate total evidence phylogenies.     

A NUMERICAL TAXONOMIC STUDY OF THE GENUS PLATANUS BASED ON MORPHOLOGICAL AND PHENOLIC CHARACTERS

Forty-two morphological and eighty chemical (phenolic) characters were employed on a numerical taxonomic study of the genus Platanus. Ten taxa were used for morphological study, and nine were available for chemical study. UPGA was employed for cluster analysis; correlation coefficients served as a measurement of the similarity between each OTU-pair. Comparison was made for phenograms and graph diagrams of nine taxa based on morphological characters with those based on chemical characters. It has been found that the two agree with each other in many respects. Correlation coefficient between similarity matrices based on morphological and chemical characters is 0.573. The result generally supports the belief that taxa closely related on morphological grounds are similar biochemically. A systematic consideration of the genus has been made, based on the information available.     

A new approach to an old conundrum--DNA barcoding sheds new light on phenotypic plasticity and morphological stasis in microsnails (Gastropoda, Pulmonata, Carychiidae)

The identification of microsnail taxa based on morphological characters is often a time-consuming and inconclusive process. Aspects such as morphological stasis and phenotypic plasticity further complicate their taxonomic designation. In this study, we demonstrate that the application of DNA barcoding can alleviate these problems within the Carychiidae (Gastropoda, Pulmonata). These microsnails are a taxon of the pulmonate lineage and most likely migrated onto land independently of the Stylommatophora clade. Their taxonomical classification is currently based on conchological and anatomical characters only. Despite much confusion about historic species assignments, the Carychiidae can be unambiguously subdivided into two taxa: (i) Zospeum species, which are restricted to karst caves, and (ii) Carychium species, which occur in a broad range of environmental conditions. The implementation of discrete molecular data (COI marker) enabled us to correctly designate 90% of the carychiid microsnails. The remaining cases were probably cryptic Zospeum and Carychium taxa and incipient species, which require further investigation into their species status. Because conventional reliance upon mostly continuous (i.e. nondiscrete) conchological characters is subject to fallibility for many gastropod species assignments, we highly recommend the use of DNA barcoding as a taxonomic, cutting-edge method for delimiting microsnail taxa.     

Taxonomy of the Solidago virgaurea Group (Asteraceae) in Poland,with Special Reference to Variability along an Altitudinal Gradient

The morphological differentiation and taxonomic treatment of lowland and high-mountain morphotypes within the Solidago virgaurea group are controversial. To clarify the taxonomic status of these taxa, we conducted a morphometric analysis of 1,746 individuals from 80 localities along an altitudinal gradient from the lowlands of northern Poland to the Carpathians and Sudetes of southern Poland. Multivariate morphometric analyses, cluster analyses and principal component analyses, were used to examine the morphological differentiation within the S. virgaurea group in Poland. Canonical discriminant analysis was applied to determine the morphological characters that best discriminate among the taxa. The stability of the high-mountain Solidago minuta morphotype was tested in an experimental field established in lowland Poland; individuals transplanted from various mountain sites were cultivated at this site, and the morphotypes remained stable in terms of their floral and vegetative characters. Multivariate analyses revealed two morphologically distinct taxa in the S. virgaurea group, which correspond to lowland S. virgaurea s. str. and high-mountain S. minuta as recognised in some European floras. The most important morphological characters for distinguishing the taxa are the number of tubular florets per capitulum, inner involucral bract width and involucre height. Vegetative and inflorescence characters appear to have less taxonomic value because they changed continuously with altitude. A key for identifying S. virgaurea and S. minuta in Poland is presented.     

Morphological and molecular variation in tiger beetles of the Cicindela hybrida complex: is an ‘integrative taxonomy’ possible?

Current taxon assignments at the species level are frequently discordant with DNA-based analyses. Recent studies on tiger beetles in the Cicindela hybrida complex identified discordance between mtDNA patterns and the entities currently defined by the taxonomic literature. To test the accuracy of morphologically delimited groups, five named taxa (species) from 24 representative sampling sites across Europe were scored for 41 external morphological characters. Three of the named taxa were 'diagnosable', that is, defined by between one and three characters unique to each group. Newly sequenced ITS1 and existing mitochondrial cox1 markers established 20 and 22 different haplotypes, respectively, but only cox1 produced (four) diagnosable units. Phylogenetic analysis and statistical parsimony networks showed poor congruence of character variation with the taxonomic entities (and each other). Variation in morphological characters was therefore tested directly for association with DNA-based nesting groups at various hierarchical levels using permutational contingency analysis. Significant statistical associations of 11 (of 13 variable) morphological characters were observed with nesting groups from ITS1 and mitochondrial DNA markers, predominantly at the 4-step level. The analysis demonstrates the need for formal tests of congruence with morphological variation at the level of individual characters, a step that is omitted from recent studies of 'integrative taxonomy'. In addition, statistical correlation of particular morphological characters with DNA-based nesting groups can identify the lowest hierarchical level at which various character sets show congruence, as a means to define evolutionarily separated entities supported by diverse data sources.     

Taxon sampling, character sampling and systematics: how gradist presuppositions created additional ganglia in gastropod euthyneuran taxa

In gastropods, the pentaganglionate condition of the nervous visceral loop has been accepted as a general character and one of the most important synapomorphies of the Euthyneura. The review of published data on 50 generic taxa shows an extreme confusion in both terminology and application of the homology concept to the two parietal ganglia observed in some Euthyneura, in addition to the three observed in most gastropods. A parsimonious re-interpretation of the data leads to the conclusion that the occurrence of five visceral ganglia is ascertained in only six genus-group taxa, and therefore cannot be accepted as a general character of Euthyneura. We propose that in phylogenetic analysis, taxonomic sampling should be determined according to the variability of characters and independently of the rank of the taxa taken into account, until every taxon in the data matrix is monomorphic for every character, and until all the taxa in which the characters occur are represented in the data matrix. We propose to use the term 'domain of definition' of a character for such a taxonomic sample. Implementing the domain of definition of characters in construction of data matrices would avoid the abuse of generalities leading to circularity in evolutionary interpretations of classification, which in the case of Euthyneura result from an a priori gradist interpretation of the evolution of the nervous system.     

国产木兰科含笑亚族植物的叶结构及其分类学意义

为了探讨含笑亚族Micheliinae植物属间关系以及含笑属Michella属下等级的划分和一些种的分类学地位,利用放大镜和体视镜对国产含笑亚族植物3属共28个分类群的叶结构特征进行了观察与研究。结果表明：含笑属、合果木属Paramichelia和观光木属Tsoongiodendron植物的脉序类型、一级脉、二级脉及其间脉和三级脉等特征表现出较高的一致性,三属间无明显的划分界限;但是,盲脉及其分支、网眼的发育和大小、叶缘末级脉等叶结构特征存在种间差异。在含笑属中,树状盲脉首次被观察到。用UPGMA对所研究28个分类群、木兰属Magnolia两个亚属各2种和鹅掌楸Liriodendron chinense的叶结构特征和形态学特征共46个性状进行聚类分析。分析结果表明：（1）合果木Pbaillonii和观光木T.odorum与含笑属的种聚为一支,因此,支持将合果木属和观光木属归并入含笑属;（2）这些特征为含笑属内组的划分提供了分类学意义;（3）基于叶结构特征、形态学特征、地理分布、聚类分析,对含笑属内一些种类的分类地位进行了讨论。     

试谈禾本科植物生殖器官主要性状的分类价值及其适用等级

生殖器官性状一直是禾本科植物分类的主要依据,但由于各个性状所附实体的形态特点、着生位置、发育程度和环境饰变的差异,其分类价值是不尽相同的。为了克服该类性状使用上的种种弊病,本文特对主要宏观性状的分类价值进行了评述,总结了它们在应用中各自适宜的等级范围。其中象花序的类型、小穗的着生、小花和果实的形状等价值较高,通常适合于族级以上类群的划分;花序的形状、小穗的排列、果实的类型等价值偏低,通常适合于属、种级类群的区分;而花序的长短与粗细、小穗轴、内稃等价值较低,通常适合于种级或种级之下类群的鉴分。     

PATTERNS OF VARIATION IN LEVELS OF HOMOPLASY

Patterns of variation in levels of homoplasy were explored through statistical analyses of standardized consistency indexes. Data were obtained from 60 recent cladistic analyses of a wide variety of organisms based on several different kinds of characters. Consistency index is highly correlated with the number of taxa included in an analysis, with homoplasy increasing as the number of taxa increases. This observation is compatible with a simple model of character evolution in which 1) the probability of character-state change increases with the total number of branches in a tree and 2) the number of possible states of a character is limited. Consistency index does not show a significant relationship to the number of characters utilized in an analysis or to the taxonomic rank of the terminal taxa. When the relationship between consistency index and number of taxa is taken into account, there is no significant difference between plant and animal data sets in the amount of homoplasy. Likewise, the level of homoplasy in morphological and molecular data sets does not appear to differ significantly, although there are still too few molecular studies to be confident of this result. Future comparisons of consistency indexes, including studies along the lines established here, must take into account the influence of the number of taxa on homoplasy.     

Taxonomic implication of embryo micromorphology in the genus <Emphasis Type="Italic">Vicia</Emphasis> L. (Fabaceae)

In this work, embryos of selected Vicia species were examined to reveal the micromorphological characters that could have taxonomic significance. Experimental results show that morphological characters such as cotyledons shape and colour, radicle shape, colour and position, plumule colour and stipular parts attachments are variable and could be used for taxa identification in the genus Vicia. Numerical analysis based on 38 micromorphological characters was used to build a phenogram that indicated the relationships among the studied taxa. In addition, an identification key using embryo characters was prepared for Vicia species. The variability of embryo characters were discussed in the taxonomic context. Although the embryo characters have only limited phylogenetic signal for Vicia species, they might be used for their morphological delimitation.