Chromosome number and flavonoid synthesis in Briza L. (Gramineae)

Following a recent reidentification of the apigenin C-glycosides in diploid Briza media, the luteolin C-glycosides were reexamined and three acylated derivatives of a luteolin C-glycoside were found. In an attempt to identify the chromosome or group of chromosomes responsible for the change in flavonoid synthesis from 4'-hydroxy- in diploid plants to 3',4'-dihydroxyflavone C-glycosides in autotetraploid plants, leaf flavonoids of artificially produced aneuploids of B. media were examined. Among these plants three different leaf flavonoid profiles were recognized: diploid, tetraploid, and a "modified" tetraploid pattern. All the aneuploids with the normal or "modified" tetraploid pattern were trisomic for one of the small acrocentric chromosomes. Induced polyploids of other Briza species were usually found to have similar flavonoid patterns in the two chromosome races. Flavonoid sulfates were found in three South American species but are absent from all the European species.     

A morphological and chemical analysis of geographical variation in Tilia L. of eastern North America

A statistical analysis of morphological variation and a Chromatographic analysis of flavonoid variation were performed to determine taxonomic relationships among the species ofTilia of eastern North America. No apparent morphological discontinuities were seen between populations within the sample area although two characters (involving leaf pubescence and gland length) showed definite patterns of geographical variation. Flavonoid patterns showed definite differences between northern and southern populations with an intermediate zone in the Smoky Mountain region. The continuous nature of the morphological and flavonoid variation suggested that the genus as represented in eastern North America should be regarded as one species,Tilia americana L.     

FLAVONOID DIVERSIFICATION IN THE ACHILLEA AGERATIFOLIA AND A. CLAVENNAE GROUPS (ASTERACEAE)

The Achillea ageratifolia and A. clavennae groups (Asteraceae, tribe Anthemideae) were investigated for intra- and interspecific leaf flavonoid variation. Numerous flavonoid glycosides, mostly unidentified, and variously methylated free aglycones based on scutellarein, 6-hydroxyluteolin, quercetagetin, and 6-hydroxy-kaempferol were detected. The distribution of methylated aglycones among individuals of A. ageratifolia was used to model the putative biosynthetic pathways. Several steps in the biosynthesis probably involve enzymes (methyltransferases) with strict positional specificities and broader substrate specificities. Geographical patterns in the flavonoid content of A. ageratifolia were only partly consistent with the current concept of A. ageratifolia. Different flavonoid profiles in A. ageratifolia do not appear to be of crucial importance in its adaptation to different habitats. The species of the A. clavennae group were clearly separable on flavonoid profiles and the presence of a hybrid population was supported by the flavonoid data. Interspecific differences in number of glycosides in relation to the number of free aglycones are discussed.     

Edaphic races and phylogenetic taxa in the Lasthenia californica complex (Asteraceae: Heliantheae): an hypothesis of parallel evolution

Lasthenia californica sensu Ornduff consists of two races that differ in their flavonoid pigments and edaphic tolerances. Recent phylogenetic studies of Lasthenia have revealed that members of L. californica sensu Ornduff belong to two phylogenetic species. The relationship of the edaphic races to these new species and to each other is the focus of this study. Characterization of flavonoid profiles and phylogenetic placement of 33 populations demonstrates that races and phylogenetic taxa are not concordant, suggesting that one or both edaphic races evolved in parallel in the two clades. We hypothesize an edaphically linked ecological role for flavonoid differences that first revealed the existence of two races.     

Cuticular hydrocarbon profiles as a taxonomic tool: advantages,limitations and technical aspects

Cuticular hydrocarbons (CHCs) are expressed on an insect's cuticle and are one of the major factors allowing insects to identify members of their own species, colony and gender. As a result of their species‐specificity, CHCs are increasingly used to delimit species in addition to more conventional methods, such as morphology or genetic markers, and so play an important role in chemotaxonomy. Species vary in the type of CHCs that they produce, as well as in the relative quantities of shared compounds. This review summarizes not only how taxonomists may differentiate between species based on CHC profiles, but also the incentive for using CHC composition as taxonomic tool. Benefits regarding the identification of cryptic species and early signs of reproductive isolation are then discussed, giving examples from studies of taxonomy, behaviour and biosynthesis. For taxonomic characters to reliably indicate species boundaries, their limitations need to be known. Potential problems caused by environmental effects, intra‐species variation in profiles and other technical issues are highlighted, and suggestions are made regarding their avoidance. It remains a challenge to determine the variation beyond which two species can be called independent; a problem shared by most methods of delimitation. Recently, there has been a shift towards using a combination of different taxonomic tools, both molecular and non‐molecular, to test observed species differences.     

SHOREBIRDS OF COASTAL BUENOS AIRES PROVINCE, ARGENTINA

The Pampas shorebird community is comprised of species from diverse taxonomic and faunal origin. Four major groups can be recognized: North American migrants residing in coastal Buenos Aires Province during their non-breeding season, Patagonian species wintering locally but breeding further south, Pampean species breeding locally, and Brazil–Paraguayan species present during their breeding season. Because of differences among these groups in the timing and migration patterns, community composition shows marked seasonal variation. Both nesting and non-breeding birds use a diversity of habitat types ranging from littoral sandy beaches to upland grasslands. Throughout the year, however, and in all habitat types, non-breeders predominate in species number and abundance. Intra- and inter-specific patterns of aggression suggest both that resources are limiting, and that non-breeding migrants may play an important role in determining breeding community composition.     

Flavonoid races in lasthenia (Compositae)

Nine of the 13 taxa ofLasthenia in which two or more populations were examined for flavonoid constituents exhibited interpopulation variation in these constituents. In certain species entire classes of compounds were present in some races and absent from others. Some of these biochemical differences are due to the failure of certain steps to occur in the biosynthesis of various flavonoids from precursor compounds. Another pattern of variation involves intraspecific differences in the nature of flavonoid glycosides that are produced. In view of the close biosynthetic relationships among all the flavonoids produced byLasthenia, the genetic differences among the flavonoid races of a species may be small. Whether or not these biochemical differences have any adaptive significance is problematical at present.     

Relationship between song characters and morphology in New World pigeons

We studied the pattern of variation in song characters among 16 New World pigeon species belonging to different taxonomic groups defined by morphological characters. Structural, temporal and frequency characters of the song were analysed. Principal components analyses showed that species belonging to the same taxonomic group were also grouped together by their song characters. In addition, individuals were correctly assigned into taxonomic groups by discriminant function analyses in more than 87.8% of cases. These analyses also showed that more than 87.5% of the individuals could be correctly classified by species when all song characters were included. Correct classification of individuals by species and taxonomic groups dropped when character types were analysed separately, thus showing that structural, as well as temporal and frequency characters are fundamental to define species- and group-specific identities of New World pigeon's songs. Correspondence between patterns of vocal and morphological variation found in this study can be a consequence of evolutionary changes in morphology affecting song production, as for example body size changes that constrain the syrinx to produce certain acoustic frequencies.     

INTRASPECIFIC VARIATION IN ABIES LASIOCARPA FROM BRITISH COLUMBIA AND WASHINGTON

Sixteen natural stands of Abies lasiocarpa (Hook.) Nutt. were sampled from British Columbia and Washington to investigate patterns of intraspecific variation in this species and to evaluate Hunt and von Rudloff's recognition of two species of subalpine fir. Principal components analysis and canonical variates analysis were performed separately on seed-cone data, needle morphology data, and needle flavonoid data. Analysis of cone data indicated no geographical patterning of populations, but eastern and western groups of populations were segregated in both the needle morphology and flavonoid analyses. With the exception of the Vancouver Island population, three geographic groups were discerned based on their needle morphology: 1) populations from the coastal mountains of British Columbia, 2) those from the Cascade Mountains of Washington, and 3) those from the eastern interior of British Columbia. Although the Vancouver Island population was grouped with the interior British Columbia populations based on needle morphology, it was similar to the other coastal populations based on flavonoid data. These inconsistent results among the three different types of taxonomic evidence underscore the need to consider a variety of traits when drawing taxonomic conclusions in Abies. Although the delineation of eastern and western groups is not wholly consistent for the different data sets, the results support recognition of coastal and interior varieties of subalpine fir.     

Molecular operational taxonomic units as approximations of species in the light of evolutionary models and empirical data from Fungi

During the last couple of decades, an increasing number of studies use sequence clusters as units for taxonomic diversity. It is well known that such molecular operational taxonomic units (MOTUs) do not necessarily correspond to species, but they are treated as such when measuring diversity and testing theories. Here, I show that data from studies of molecular evolution and species diversification of fungi indicate that commonly used cut‐offs are likely to lump species in many cases. At the same time, empirical studies show that the mean within‐species variation is close to these cut‐offs. That the within‐species variation estimates are plausible is supported by coalescence modelling under a range of parameter settings. In addition, studies using crossing tests to delimit species show that there often is an overlap in within‐ and between‐species distances. The available data therefore indicate that sequence clusters are likely to misrepresent species. However, to keep a biological relevance, MOTUs should be kept in close agreement with species. Studies using them should therefore asses how sensitive the results are to differences between MOTUs and species – something that is rarely done. An even better solution is to directly include the uncertainty in species delimitation in the analyses, but in many cases, we need to increase our knowledge of taxonomy and evolution to do this accurately. Even if the empirical data referred to here pertain to the “barcoding” region of rDNA in fungi, there is nothing indicating that the situation is substantially better for other taxa or genes.     

Flavonoid chemistry and angiosperm evolution

A consideration of the distribution of flavonoid compounds in angiosperms indicates that exceptions exist to current thought on the presence of particular structural types occurring in primitive versus advanced flowering plants. As additional thorough survey work is done, the exceptions become increasingly common and the generalizations are weakened. A methodological problem in flavonoid surveys concerns documenting the “absence” of particular compounds and the question of quantitative versus qualitative variation of certain constituents. Consideration of flavonoid biosynthesis suggests that simple genetic differences likely control the classes of compounds present and this in turn indicates that caution be used in placing phylogenetic significance on such differences. Features of floral morphology used in studying angiosperm phylogeny have a complex genetic-developmental basis as compared to the genetic factors governing the presence of various flavonoid classes. This ostensibly is an important factor in explaining why reversals in certain trends of floral morphology are rarely noted and why these features are usually constant at higher taxonomic levels. By contrast, variation of flavonoid classes (by virtue of the small genetic differences controlling the presence of different classes) occurs at lower taxonomic levels. Genetic and enzymological studies of flavonoid biosynthesis also indicate that a single compound may be synthesized via different pathways, and this has significant implications for the use of flavonoid distribution in a phylogenetic sense. Given similar selection pressures, the same compounds may arise independently in distantly related plants. Clearly, this has occurred with floral anthocyanidins, where the distribution of particular compounds is related to pollinators. Flavonoid compounds will continue to be useful systematically at the generic level or lower, and possibly at the familial level in some instances. However, studies of the genetics and enzymology of flavonoid compounds in different groups of plants are needed if flavonoids are to be employed in a phylogenetic or evolutionary sense at higher taxonomic levels in the angiosperms. Much additional work in the difficult area of flavonoid functions is to be desired. Many more investigations of comparative flavonoid chemistry of fossil and extant members of what are considered the same genus must be carried out if any appreciation of flavonoid change through evolutionary time is to be achieved.     

Differential gene flow of mitochondrial and nuclear DNA markers among chromosomal races of Australian morabine grasshoppers (Vandiemenella, viatica species group)

Recent theoretical developments have led to a renewed interest in the potential role of chromosomal rearrangements in speciation. Australian morabine grasshoppers (genus Vandiemenella, viatica species group) provide an excellent study system to test this potential role of chromosomal rearrangements because they show extensive chromosomal variation and formed the basis of a classic chromosomal speciation model. There are three chromosomal races, viatica19, viatica17, and P24(XY), on Kangaroo Island, South Australia, forming five parapatric populations with four putative contact zones among them. We investigate the extent to which chromosomal variation among these populations may be associated with barriers to gene flow. Population genetic and phylogeographical analyses using 15 variable allozyme loci and the elongation factor-1alpha (EF-1alpha) gene indicate that the three races represent genetically distinct taxa. In contrast, analyses of the mitochondrial cytochrome c oxidase subunit I (COI) gene show the presence of three distinctive and geographically localized groups that do not correspond with the distribution of the chromosomal races. These discordant population genetic patterns are likely to result from introgressive hybridization between the chromosomal races and range expansions/contractions. Overall, these results suggest that reduction of nuclear gene flow may be associated with chromosomal variation, or underlying genetic variation linked with chromosomal variation, whereas mitochondrial gene flow appears to be independent of this variation in these morabine grasshoppers. The identification of an intact contact zone between P24(XY) and viatica17 offers considerable potential for further investigation of molecular mechanisms that maintain distinct nuclear genomes among the chromosomal races.     

Chemodiversity of exudate flavonoids in Dionysia (Primulaceae): A comparative study

More than 60 accessions of various Dionysia spp. were analysed for their exudate flavonoid composition. Many Dionysia spp. accumulate the typical Primula flavonoids with irregular substitution (unsubstituted flavone, its 2′,5′-substituted derivatives and corresponding 5-OH-flavones), but flavones, flavonols and flavanones with regular 5,7-diOH-substitution are also encountered in their exudates. The formation of both types of flavonoids is not mutually exclusive. This paper analyses the chemodiversity of Dionysia exudates with respect to infraspecific variability, infrageneric distribution, patterns in hybrid taxa, and comparisons of biogenetic tendencies between Dionysia and closest related species of Primula. The uniqueness of occurrence of Primula-type flavonoids in the family Primulaceae, and their presumed different biosynthetic origin, suggest significance as further character in the Primula–Dionysia assemblage. Principal component analysis was applied to test the significance of variation of flavonoid composition across Dionysia. Comparative analysis of flavonoid profiles against the current taxonomic views yielded correlations, confined to the level of smaller groups, and only in parts at level of the current infrageneric concept. Flavonoid data are further discussed against the background of morphological and biogeographic differentiation of the genus. Increased diversification of flavonoid profiles may be interpreted as a derived status in Dionysia, which agrees with current views on the phylogeny of Dionysia as a specialised group within Primula. Functional aspects of exudate flavonoid formation are shortly addressed.     

The effect of phylogeny on interspecific body shape variation in darters (Pisces: Percidae)

We conducted a geometric morphometric analysis of interspecific body shape variation among representatives of 31 species of darters (Pisces: Percidae) to determine whether there is evidence of a phylogenetic effect in body shape variation. Cartesian transformation grids representing relative shape differences of individual species and subspecies revealed qualitative similarities within most traditionally recognized taxonomic groups (genera and subgenera). Canonical variates analysis and a UPGMA cluster analysis were conducted to explore further the relationships among body shapes of species; both analyses revealed patterns of variation consistent with the interpretation that shape is associated with taxonomic affinities. Normalized Mantel statistics revealed a significant positive association between body shape differences and phylogenetic interrelatedness for each of four recent phylogenetic hypotheses, providing evidence of a phylogenetic effect. This result is somewhat surprising, however, given the largely incompatible nature of these four phylogenies. We provide evidence that this result may be due to (1) the inclusion of multiple sets of closely related species to represent the traditionally recognized genera and subgenera within each phylogeny and/or (2) the inclusion of several species with relatively divergent shapes and their particular positions within the phylogenies relative to one another or to the other species of darters.     

Geographic variation in the plumage coloration of willow flycatchers Empidonax traillii

The ability to identify distinct taxonomic groups of birds (species, subspecies, geographic races) can advance ecological research efforts by determining connectivity between the non‐breeding and breeding grounds for migrant species, identifying the origin of migrants, and helping to refine boundaries between subspecies or geographic races. Multiple methods are available to identify taxonomic groups (e.g., morphology, genetics), and one that has played an important role for avian taxonomists over the years is plumage coloration. With the advent of electronic devices that can quickly and accurately quantify plumage coloration, the potential of using coloration as an identifier for distinct taxonomic groups, even when differences are subtle, becomes possible. In this study, we evaluated the degree to which plumage coloration differs among the four subspecies of the willow flycatcher Empidonax traillii, evaluated sources of variation, and considered the utility of plumage coloration to assign subspecies membership for individuals of unknown origin. We used a colorimeter to measure plumage coloration of 374 adult willow flycatchers from 29 locations across their breeding range in 2004 and 2005. We found strong statistical differences among the mean plumage coloration values of the four subspecies; however, while individuals tended to group around their respective subspecies’ mean color value, the dispersion of individuals around such means overlapped. Mean color values for each breeding site of the three western subspecies clustered together, but the eastern subspecies’ color values were dispersed among the other subspecies, rather than distinctly clustered. Additionally, sites along boundaries showed evidence of intergradation and intermediate coloration patterns. We evaluated the predictive power of colorimeter measurements on flycatchers by constructing a canonical discriminant model to predict subspecies origin of migrants passing through the southwestern U.S. Considering only western subspecies, we found that individuals can be assigned with reasonable certainty. Applying the model to migrants sampled along the Colorado River in Mexico and the U.S. suggests different migration patterns for the three western subspecies. We believe that the use of plumage coloration, as measured by electronic devices, can provide a powerful tool to look at ecological questions in a wide range of avian species.     

Comparative chiasma analysis using a computerised optical digitiser

A new computerised technique has been devised for measuring the distribution of chiasmata along diplotene bivalents. The method involves the introduction into the field of view of the microscope, of a fine light spot which can be accurately manipulated along the chromosomes of each bivalent. The data recorded include (a) the positions of the chiasmata along the bivalent in terms of their relative distances from the centromere and (b) the individual bivalent and cellular chiasma frequencies. — The method has been applied to the analysis of chiasma distribution patterns in the two known species of the genus Caledia, C. species nova 1 and C. captiva and in two chromosomal races of the latter. Statistical tests indicate that within bivalents at least 40% of the comparative distribution patterns of chiasmata between races and species are significantly different. Similar comparisons between populations within races reveal only 18% significant differences. — The observed distribution patterns of chiasmata in this genus suggest that chiasma formation is sequential from centromere to telomere. — The variation in the frequency and distribution of chiasmata between races and species suggests that the interference distances between successive chiasmata are, at least partially, independent of chiasma frequency and position. — The interracial and interspecific differences in chromosome structure are correlated with changes in chiasma pattern.     

Some synchorological aspects of basiphilous pine forests in Fennoscandia

Basiphilous pine forests and related birch forests are herb-and grass-rich forests on calcareous substrate. These forests are complex communities with floristic/ecological elements from different vegetation types occurring in a subtle micromosaic. These elements are e.g. species from acidophilous conifer forests, thermophilous forest-rim communities, calcareous shallow-soil and steppe communities, eutrophic wet meadows and fens, and in northern Fennoscandia also species from alpine Dryas heaths. Four associations are recognized in Fennoscandia: Convallario-Pinetum, Melico-Piceetum pinetosum, Peucedano-Pinetum and Epipacto atrorubentis-Betuletum. The main association is the Convallario-Pinetum, a widespread community in Fennoscandia and Estonia with a considerable floristic variation between the different regions. Examples of the floristic variation along west-east profiles and south-north profiles in Fennoscandia are presented. The basiphilous pine forest complex can be divided into a number of ecological types along the moisture and nutritional gradients. A further subdivision into geographical types (races) is presented.Nomenclature follows Lid (1974) for vascular plants, Nyholm (1954–1969) for musci and Dahl & Krog (1973) for lichens.     

Taxonomic significance of flavonoid variation in temperate species of Nothofagus

Forty-two flavonoids and a stilbene (pinosylvin) were identified in the leaf exudates of 11 temperate species of Nothofagus from South America, Australia and New Zealand. The flavonoid profiles demonstrate significant taxonomic value at the subgeneric level. Most species of subgenus Fuscospora are characterized by the presence of pinosylvin, galangin and galangin methyl ethers. Kaempferol-type flavonols are abundant in subgenus Lophozonia while these flavonols are largely absent from species of subgenus Fuscospora. The flavonoid patterns are largely in agreement with a recent subgeneric classification of Nothofagus.     

非环境类因子对物种数目协同变化的影响

不同分类类群的物种数目常在空间上表现出显著相关地协同变化,但哪些相关系数之间存在较大的差异？究竟是什么因素导致了这种差异是值得关注的问题。从不同作者的研究方法和数据来源来看,不同研究中的研究方法、研究区域和环境条件本身就存在着差异。除以上影响因子外,我们分析了非环境类因子对物种数目协同变化的影响。结果发现分类类群间的物种数量协同变化差异明显,只有起源和生境要求相似的类群间呈显著性相关;不同鸟兽间的协同变化不存在面积效应,但是空间尺度间的相关性差异明显：物种分布型中东洋型物种的协同变化明显,而广布型和古北型不明显;在鸟类居留型中繁殖鸟与兽类的协同变化极为显著,而其他类型则不显著。综上所述,物种数量协同变化的非环境类影响因子中,生态类型和起源对分类类群间的物种数目协同关系有重要影响,