Karyotypic analysis of Cajanus,Atylosia, and Rhynchosia species

Summary Somatic chromosomes of two cultivais of Cajanus cajan, eight species of Atylosia (A. albicans, A. cajanifolia, A. lineata, A. platycarpa, A. scarabaeoides, A. serica, A. trinervia and A. volubilis), and of Rhynchosia rothii were analysed. All species had 2n=22. Eight of the 10 species studied had two pairs of satchromosomes while A. scarabaeoides and A. sericea had only one sat-chromosome pair. Based on relative chromosome length (L%), arm ratio (pa-value) and presence or absence of secondary constriction, a karyotype formula for each species was formulated. Based on these parameters the chromosome pairs could also be assigned to groups ranging from 8 to 10 in different species. Except for the asymmetrical karyotype of A. albicans, the other species had rather moderately symmetrical karyotypes.     

4种弹涂鱼鳃的形态度量学比较及其生态学意义

通过对背眼虎鱼亚科中薄氏大弹涂鱼(Boleophthalmus boddarti)、青弹涂鱼(Scartelaos histophorus)、新几内亚弹涂鱼(Periophthalmus novaeguineaensis)和点弹涂鱼(P.spilotus)3属4种弹涂鱼鳃参数的测定,比较了各种之间鳃的形态度量学差异。结果表明,4种弹涂鱼的鳃参数(Y)与其体重(W)均符合方程logY=log a+b logW,且各鳃参数与体重的相关性显著(R2=0.50～0.98,P0.05)。等体重的弹涂鱼相比较,青弹涂鱼的总鳃丝数、总鳃丝长(mm)、鳃丝一侧鳃小片数(/mm)、总鳃面积(mm2)和相对鳃面积(mm2/g)均最大,薄氏大弹涂鱼相应鳃参数次之,新几内亚弹涂鱼和点弹涂鱼相应鳃参数较小。弹涂鱼鳃结构的这种梯度退化,表明青弹涂鱼和薄氏大弹涂鱼水生性较强,而新几内亚弹涂鱼和点弹涂鱼陆生性较强。4种弹涂鱼的总鳃丝长和总鳃面积明显小于其他等体重水生鱼类,这与弹涂鱼的两栖生活特征相符。     

Molecular phylogeny of the subgenus Drosophila (Diptera, Drosophilidae) with an emphasis on Neotropical species and groups: a nuclear versus mitochondrial gene approach

The genus Drosophila has played an essential role in many biological studies during the last 100 years but much controversy and many incompletely addressed issues still remain to be elucidated regarding the phylogeny of this genus. Because information on the Neotropical species contained in the subgenus Drosophila is particularly incomplete, with this taxonomic group being underrepresented in many studies, we designed a study to answer some evolutionary questions related to these species. We subjected at least 41 Drosophilidae taxa to a phylogenetic analysis using a 516-base pair (bp) fragment of the alpha-methyldopa (Amd) nuclear gene and a 672 bp fragment of the mitochondrial cytochrome oxidase subunit II (COII) gene both individually and in combination. We found that the subgenus Drosophila is paraphyletic and subdivided into two main clusters: the first containing species traditionally placed in the virilis-repleta radiation and the second assembling species of the immigrans-Hirtodrosophila radiation. Inside the first of these clusters we could detect the monophyly of both the flavopilosa (the sister-clade of the annulimana group) and the mesophragmatica (closely related to the repleta group) species groups. Concerning the immigrans-Hirtodrosophila lineage, Zaprionus, Liodrosophila, Samoaia, and Hirtodrosophila were the early offshoots, followed by the immigrans, quinaria, testacea, and funebris species groups. The tripunctata radiation appears to be a derived clade, composed of a paraphyletic tripunctata group, intimately interposed with members of the cardini, guarani, and guaramunu species groups. Overall, the COII gene yielded a poor phylogenetic performance when compared to the Amd gene, the evolutionary hypothesis of which agreed with the total evidence tree. This phenomenon can be explained by the fast saturation of transitional substitutions in COII, due to strong biases in both base composition and substitution patterns, as also by its great among-site rate variation heterogeneity.     

Comparison of habitat quality and diet of Colobus vellerosus in forest fragments in Ghana

The forest fragments surrounding the Boabeng-Fiema Monkey Sanctuary (BFMS) in central Ghana shelter small populations of Colobus vellerosus. Little is known about these populations or the ability of the fragments to support them, despite the fact that these fragments represent potentially important habitat for the colobus in this region. We compared the diet of three groups of C. vellerosus in the fragments to two groups in BFMS. We also examined the differences in plant species composition and food abundance among fragments. The study took place from June to November 2003. Dietary data were collected using scan sampling. Plant species composition and food abundance were evaluated using tree plots and large tree surveys. As in BFMS groups, leaves constituted the highest proportion of the diet of fragment groups, yet the colobus in fragments fed on more lianas than did those in BFMS. Over 50% of all species observed eaten by colobus in the fragments were not consumed in BFMS groups during the same season. Food abundance was similar between fragments and BFMS, although species composition differed. There was no relationship between the density of colobus and the density of food trees or percentage of food species, suggesting that other factors may be influencing the number of colobus present. This study highlights the broad dietary range of C. vellerosus, which may be a factor allowing its survival in these fragments.     

Nectary structure and nectar characteristics in someBignoniaceae

The nectary structure and chemical nectar composition of 15 species belonging to 12 genera ofBignoniaceae are analyzed. All taxa bear a conspicuous nuptial nectary surrounding the ovary base. The secretory tissue is mostly supplied by phloem branches. The stomata are located in the middle and upper part of the nectary epidermis with an homogeneous distribution. The nuptial nectary is proportionally large in relation to the ovary (15–30%), disregarding the nectary volume. Most species have extranuptial nectaries in both inner and outer surfaces of the calyx. Both kinds of nectaries lack a vascular tissue that straightly supplies them. Nuptial nectar concentration (wt/wt) ranges from 19 to 68%. Sugars and amino acids are found in all species. Half of the species have hexose predominant nectars, the remaining sucrose predominant. Phenols are detected in only three species, whereas reducing acids exclusively inTecoma stans. Alkaloids and lipids were never detected. Extranuptial nectar chemical composition is analyzed in two species:Dolichandra cynanchoides andPodranea ricasoliana. Bees constitute the main flower visitors of the species studied whereas hummingbirds were seen visiting three species. A correlation analysis is performed with the data obtained. There are a few significant correlations which indicate a parallel increase of three parameters: the longer the flower length, the more voluminous the nectary and the higher stomata number, independently of the floral biotype. Phenograms are obtained using 24 floral characters including nectary and nectar data. The clusters obtained do not reflect taxonomic relationships but are useful in the understanding of animal-plant interactions when the flower biotype is considered.This paper is based on a chapter of a doctoral thesis presented at the University of Córdoba (Argentina).     

Isozyme polymorphism in some yellow- and blue-floweredVigna species complexes (Fabaceae, Phaseoleae)

An electrophoretic comparison of variation at 28 isozyme loci was performed for 58Vigna accessions belonging to theV. luteola, V. ambacensis, andV. racemosa groups of species. In all three groups, strong divergence is noted between results and actual nomenclature.     

Diverse bacteria isolated from root nodules of Phaseolus vulgaris and species within the genera Campylotropis and Cassia grown in China

Eighty bacterial isolates from root nodules of the leguminous plants Phaseolus vulgaris, Campylotropis spp. and Cassia spp. grown in China were classified into five groups by phenotypic analyses, SDS-PAGE of whole-cell proteins, PCR-based 16S rRNA gene restriction-fragment-length-polymorphism and sequencing. Thirty-three isolates from the three plant genera were identified as Agrobacterium tumefaciens because they are closely related to the type strain of A. tumefaciens. Fourteen isolates from P. vulgaris grown in Yunnan and Inner Mongolia were classified as R. leguminosarum bv. phaseoli based on their close relationship with the type strain in numerical taxonomy and in 16S rDNA phylogeny. Twenty-seven isolates from Campylotropis delavayi, P. vulgaris and four species of Cassia grown in the central zones of China were classified into three groups within the genus Bradyrhizobium. One of these three groups could be defined as Bradyrhizobium japonicum. Our results demonstrated that P. vulgaris and the species of Campylotropis and Cassia could form nodules with diverse rhizobia in Chinese soils, including novel lineages associated with P. vulgaris. These results also offered information about the convergent evolution between rhizobia and legumes since the rhizobial populations associated with P. vulgaris in Chinese soils were completely different from those in Mexico, the original cite of this plant. Some rhizobial species could be found in all of the three leguminous genera.     

A comparative study of the food niches of lake-dwelling triclads and leeches

The food niches of four species of triclads and three species of non-parasitic leeches living in the littoral zone of British lakes of different trophic status were investigated, over one year, using a serological technique. Antisera against ten potential prey groups were employed. The basic data were adjusted to compensate for differences in predator size and seasonal changes in field temperatures. Data on two of the leech species have been presented elsewhere, but comparisons of the diet of all seven predator species are made in this paper. Much overlap in diet between the various predator species occurs, but, with one exception, each of the genera has a major food resource. The Polycelis spp. feed extensively on oligochaetes, Dugesia polychroa on molluscs, Dendrocoelum lacteum on Asellus, Erpobdella octoculata on chironomids and Glossiphonia complanata on molluscs. Helobdella stagnalis is a generalist feeder. Problems of coexistence of the leech species, and of the leech and triclad species are discussed.     

Electrophoretic protein patterns of three species ofPhytophthora associated with black pod disease of cocoa (Theobroma cacao L.)

When electrophoretic profiles of native proteins from vegetative mycelia ofPhytophthora palmivora, Phytophthora capsici and Phytophthora citrophthora causing black pod disease of cocoa in India were compared on a single Polyacrylamide gel, the isolates of same species were readily distinguished both qualitatively by visual similarity in banding patterns and quantitatively by calculating similarity coefficients. Similarity coefficients were generally much higher between isolates within a species than between isolates of different species. The dendrograms obtained after unweighted pair grouping with arithmetic averaging cluster analysis, revealed that all the isolates ofPhytophthora capsici were highly homogenous and formed a single cluster. The isolates ofPhytophthora citrophthora were resolved into two electrophoretic types which were clustered into two distinct sub groups.Phytophthora palmivora formed a separate group. Thus, the results reveal that polyacrylamide gel electrophoresis can be used successfully in distinguishing species and sub groups within a species ofPhytophthora encountered on cocoa. CPCRl contribution No. 914.     

Retrotransposon populations of <Emphasis Type="Italic">Vicia</Emphasis> species with varying genome size

The (non-LTR) LINE and Ty3-gypsy-type LTR retrotransposon populations of three Vicia species that differ in genome size (Vicia faba, Vicia melanops and Vicia sativa) have been characterised. In each species the LINE retrotransposons comprise a complex, very heterogeneous set of sequences, while the Ty3-gypsy elements are much more homogeneous. Copy numbers of all three retrotransposon groups (Ty1-copia, Ty3-gypsy and LINE) in these species have been estimated by random genomic sequencing and Southern hybridisation analysis. The Ty3-gypsy elements are extremely numerous in all species, accounting for 18–35% of their genomes. The Ty1-copia group elements are somewhat less abundant and LINE elements are present in still lower amounts. Collectively, 20–45% of the genomes of these three Vicia species are comprised of retrotransposons. These data show that the three retrotransposon groups have proliferated to different extents in members of the Vicia genus and high proliferation has been associated with homogenisation of the retrotransposon population.Electronic Supplementary Material Supplementary material is available for this article at .     

Phylogeny,Species Richness,and Ecological Specialization in Cyperaceae Tribe Cariceae

Cyperaceae tribe Cariceae is characterized by both species richness and habitat diversity, making it an ideal system to study ecological specialization and niche differentiation. We present a phylogenetic hypothesis for the tribe based on nuclear and chloroplast DNA sequence comparisons (ETS-1f, ITS, trnL intron, trnL-trnF intergenic spacer) for 140 representative species from five continents, and use this hypothesis to suggest patterns of both niche conservatism and niche differentiation, particularly within the large subgenus Carex. We identify a new major clade, comprising forest species of East Asian Carex section Siderostictae (subgenus Carex) as sister to the rest of tribe Cariceae. Within Carex subgenus Carex, species tolerant of water-saturated habitats occur in only a few, apparently derived groups, with varying species richness. Clades of predominantly wetland species tend to have broad geographic distribution, often with sister species on different continents, suggesting recent dispersal. In contrast, species within several clades are predominantly forest specialists with distinct Asian and North American lineages. Niche segregation along environmental gradients, such as soil moisture or acidity, is quite common among closely related wetland species, but more difficult to demonstrate within upland forest groups. More complete sampling of species within both wetland and forest groups, combined with comparable sampling of environmental preferences and testing against null models, will be needed for more rigorous exploration of the observed patterns.     

Genetic diversity in the orange subfamily Aurantioideae. II. Genetic relationships among genera and species

Genetic relationships were studied by means of ten isoenzymatic systems, at the genus and species level, using two distances and four methods of aggregation in a germplasm collection of 198 cultivars and accessions of 54 species belonging to Citrus and 13 related genera. The most consistent results were obtained by the chord distance and the neighbor-joining clustering method. Citrus species were distributed in two main groups: the orange-mandarin group and the lime lemon-citron-pummelo group. The species C. halimii and C. tachibana are not included in these groups. Mandarin species fall into three main subgroups: one includes C. sinensis; the second, C. aurantium, the third, small-fruit species. The citron, the pummelo and the ancient lemon subgroups form a cluster to which the species belonging to subgenus Papeda and the cultivated limes, lemons and bergamots are related. Microcitrus spp, to which Severinia buxifolia and Atalantia ceylanica seem to be related, cluster with the lime lemon-citron-pummelo group while Fortunella is close to the orange-mandarin group. Poncirus trifoliata, the most important species for citrus rootstock improvement is located far from Citrus but connected to it through Fortunella spp. A broad distribution of species has been found that should be taken into account to sample new genotypes in the search of desired characters in order to fully and efficiently use genetic resources for citrus improvement.     

Nectary structure of Labiatae in relation to their nectar secretion and characteristics in a Mediterranean shrub community — Does flowering time matter?

We studied the interrelation between nectary structure (13 parameters), nectar characteristics (yield, chemical composition), and flower size of 11 Labiatae species in a Mediterranean shrub community near Athens, Greece. We also explored whether the above attributes are affected by the Mediterranean summer drought constraints. Our findings show that among all nectary parameters studied, nectary size and stomatal opening are the most important in (positively) shaping nectar secretion, nectary size being the most meaningful. Nectary structure is correlated to quantity of the nectar secreted, not its quality. Wide flowers bear wide nectaries with large stomatal openings, whereas deep flowers are not related to any nectary size. Corolla size (both length and width) and nectary stomatal opening decrease with flowering time. This applies also to nectary size, nectar volume and sugar content of the perennials (9 species). All above cases of time dependence show that there is a constraint effect of Mediterranean climate on floral and nectary structure, reflected also as a decrease in nectar secretion. Nectary structure in Labiatae is largely shaped by both phylogenetic and climate constraints. On the other hand, although nectar is largely influenced by nectary structure, it is to a large extent ecologically biased, implying that, in addition to phylogeny, there are many other ecological parameters interfering in its secretion such as time within the season, life history, and light requirements.     

Changes of dung beetle communities from rainforests towards agroforestry systems and annual cultures in Sulawesi (Indonesia)

Little is known about how tropical land-use systems contribute to the conservation of functionally important insect groups, including dung beetles. In a study at the margin of Lore Lindu National Park (a biodiversity hotspot in Central Sulawesi, Indonesia) dung-beetle communities were sampled in natural forest, young secondary forest, agroforestry systems (cacao plantations with shade trees) and annual cultures (maize fields), each with four replicates (n = 16 sites). At each site we used 10 pitfall traps, baited with cattle dung, along a 100 m transect for six 3-day periods. The number of trapped specimens and species richness at the natural forest sites was higher than in all land-use systems, which did not significantly differ. Each land-use system contained, on average, 75% of the species richness of the natural forest, thereby indicating their importance for conservation. However, a two-dimensional scaling plot based on NESS indices (m = 6) indicated distinct dung beetle communities for both forest types, while agroforestry systems and annual cultures exhibited a pronounced overlap. Mean body size of dung beetles was not significantly influenced by land-use intensity. Five of the six most abundant dung beetle species were recorded in all habitats, whereas the abundance of five other species was significantly related to habitat type. Mean local abundance and number of occupied sites were closely correlated, further indicating little habitat specialisation. The low dung beetle diversity (total of 18 recorded species) may be due to the absence of larger mammals in Sulawesi during historical times, even though Sulawesi is the largest island of Wallacea. In conclusion, the dung beetle fauna of the lower montane forest zone in Central Sulawesi appears to be relatively robust to man-made habitat changes and the majority of species did not exhibit strong habitat preferences.     

Speciation in Pyricularia inferred from multilocus phylogenetic analysis

Pyricularia isolates from various host plants were subjected to a multilocus phylogenetic analysis based on rDNA-ITS, actin, β-tubulin, and calmodulin loci. A combined gene tree resolved seven groups with 100 % BS support, suggesting that they are monophyletic groups supported concordantly by all four loci. By incorporating biological and morphological species criteria, each of the seven groups was considered to be a current species. However, phylogenetic relationships among these species were unresolved in the single-gene trees and in the combined tree. Furthermore, the transition from concordance to conflict occurred more than once in the combined gene tree. They were interpreted by assuming that Pyricularia has evolved through repeated species radiation. The transition point other than the current species limit was considered to be the limit of the former species.     

Phylogenetic investigations of Sordariaceae based on multiple gene sequences and morphology

The family Sordariaceae incorporates a number of fungi that are excellent model organisms for various biological, biochemical, ecological, genetic and evolutionary studies. To determine the evolutionary relationships within this group and their respective phylogenetic placements, multiple-gene sequences (partial nuclear 28S ribosomal DNA, nuclear ITS ribosomal DNA and partial nuclear β-tubulin) were analysed using maximum parsimony and Bayesian analyses. Analyses of different gene datasets were performed individually and then combined to generate phylogenies. We report that Sordariaceae, with the exclusion Apodus and Diplogelasinospora, is a monophyletic group. Apodus and Diplogelasinospora are related to Lasiosphaeriaceae. Multiple gene analyses suggest that the spore sheath is not a phylogenetically significant character to segregate Asordaria from Sordaria. Smooth-spored Sordaria species (including so-called Asordaria species) constitute a natural group. Asordaria is therefore congeneric with Sordaria. Anixiella species nested among Gelasinospora species, providing further evidence that non-ostiolate ascomata have evolved from ostiolate ascomata on several independent occasions. This study agrees with previous studies that show heterothallic Neurospora species to be monophyletic, but that homothallic ones may have a multiple origins. Although Gelasinospora and Neurospora are closely related and not resolved as monophyletic groups, there is insufficient evidence to place currently accepted Gelasinospora and Neurospora species into the same genus.     

Domain II Hairpin Structure in ITS1 Sequences as an Aid in Differentiating Recently Evolved Animal and Plant Pathogenic Fungi

The hypothesis that ITS structural features can be used to define fungal groups, where sequence analysis is unsatisfactory, was examined in plant and animal pathogenic fungi. Structural models of ITS1 regions were predicted for presumed closely related species in Colletotrichum and Trichophyton anamorphs of Arthroderma species. Structural alignment of models and comparison with ITS sequence analysis identified a variable region in a conserved hairpin formed from a common inverted repeat. Thirteen different hairpin structure models were obtained for Colletotrichum species and five different models were obtained for Trichophyton species. The different structure types could be matched to individual species and species complexes as defined by ITS sequence analysis.     

The chromosome complements of shrubbyOxalis species from South America

Twenty species of shrubbyOxalis species native in South America were arranged in six groups according to their karyotype similarities. The first group includes more than half of the species studied, all with 2n = 12 relatively small metacentric chromosomes. The rest of the species from the other groups has different basic chromosome numbers, and exhibits various degrees of chromosome asymmetry and size increase. These latter groups apparently have specialized to habitats with low light intensity such as the forest undergrowth in contrast to the frist group whose members live in open areas (i.e., grasslands, savannas etc.).     

Characterization of rhizobia isolated from Albizia spp. in comparison with microsymbionts of Acacia spp. and Leucaena leucocephala grown in China

This is the first systematic study of rhizobia associated with Albizia trees. The analyses of PCR-RFLP and sequencing of 16S rRNA genes, SDS-PAGE of whole-cell proteins and clustering of phenotypic characters grouped the 31 rhizobial strains isolated from Albizia into eight putative species within the genera Bradyrhizobium, Mesorhizobium and Rhizobium. Among these eight rhizobial species, five were unique to Albizia and the remaining three were shared with Acacia and Leucaena, two legume trees coexisting with Albizia in China. These results indicated that Albizia species nodulate with a wide range of rhizobial species and had preference of microsymbionts different from Acacia and Leucaena. The definition of four novel groups, Mesorhizobium sp., Rhizobium sp. I, Rhizobium sp. II and "R. giardinii", indicates that further studies with enlarged rhizobial population are necessary to better understand the diversity and to clarify the taxonomic relationships of Albizia-associated rhizobia.