Home About us Contact
|
Home About us Contact | ||
|
|
||
Species Level (species + level)
Kinds of Species Level Selected AbstractsBiodiversity and distribution of epibiontic communities on Caridina ensifera (Crustacea, Decapoda, Atyidae) from Lake Poso: comparison with another ancient lake system of Sulawesi (Indonesia)ACTA ZOOLOGICA, Issue 2 2010Gregorio Fernandez-Leborans Abstract Fernandez-Leborans, G. and von Rintelen, K. 2010. Biodiversity and distribution of epibiontic communities on Caridina ensifera (Crustacea, Decapoda, Atyidae) from Lake Poso: comparison with another ancient lake system of Sulawesi (Indonesia). , Acta Zoologica (Stockholm) 91: 163,175 The epibiont communities of the shrimp Caridina ensifera, endemic to Lake Poso (Sulawesi, Indonesia), were analysed. Most of the epibiont species were ciliated protozoa belonging to three suctorian genera (Acineta, Podophrya and Spelaeophrya), three peritrich genera (Zoothamnium, Vorticella and Cothurnia), and a haptorid genus (Amphileptus). There was also a rotifer epibiont of the genus Embata. Epibionts were identified to species level. There were 14 to 1114 epibionts per shrimp. The distribution of the epibiont species on the surface of the basibiont was recorded, calculating the number on the different colonized individuals of C. ensifera. The most abundant species, Zoothamnium intermedium and Acineta sulawesiensis, were also the most widely distributed. There was a significant difference between the spatial distributions of the different epibiont species. The analysis of the number of the epibiont species throughout the anteroposterior axis of the shrimp showed a gradient from the anterior to the posterior end of the body. Data from Lake Poso were compared with those of the Malili lake system (Sulawesi), obtained from its endemic shrimp, Caridina lanceolata. Lake Poso had the highest mean diversity, while Lake Mahalona showed the highest maximum diversity. All lakes were correlated with respect to the mean number of epibionts on the anatomical units of the shrimp, which showed a similar general distribution. The distributions of the different epibiont species were compared between the lakes. The possible adaptations of the epibionts as well as the colonization patterns were discussed. From the statistical results and the analysis of the distributions, we propose that in these communities epibiont species have a pattern of colonization in which they follow a behaviour as a whole; each species has a differential distribution, with the species occupying the available substratum with the particular requirements of each functional group, but there is a trend towards maintaining an equilibrium among species and groups, compensating for diversity and number of individuals. In all lakes there was an epibiont distribution model comprising the maintenance of an anteroposterior axis gradient, which was supported by the fluctuation in diversity and number of individuals of the different functional groups of epibiont species. The functional role of the different groups of species seems to tend towards sustainability with little global variation among the lakes. [source] BIODIVERSITY RESEARCH: Genetic diversity in two introduced biofouling amphipods (Ampithoe valida & Jassa marmorata) along the Pacific North American coast: investigation into molecular identification and cryptic diversityDIVERSITY AND DISTRIBUTIONS, Issue 5 2010Erik M. Pilgrim Abstract Aim, We investigated patterns of genetic diversity among invasive populations of Ampithoe valida and Jassa marmorata from the Pacific North American coast to assess the accuracy of morphological identification and determine whether or not cryptic diversity and multiple introductions contribute to the contemporary distribution of these species in the region. Location, Native range: Atlantic North American coast; Invaded range: Pacific North American coast. Methods, We assessed indices of genetic diversity based on DNA sequence data from the mitochondrial cytochrome c oxidase subunit I (COI) gene, determined the distribution of COI haplotypes among populations in both the invasive and putative native ranges of A. valida and J. marmorata and reconstructed phylogenetic relationships among COI haplotypes using both maximum parsimony and Bayesian approaches. Results, Phylogenetic inference indicates that inaccurate species-level identifications by morphological criteria are common among Jassa specimens. In addition, our data reveal the presence of three well supported but previously unrecognized clades of A. valida among specimens in the north-eastern Pacific. Different species of Jassa and different genetic lineages of Ampithoe exhibit striking disparity in geographic distribution across the region as well as substantial differences in genetic diversity indices. Main conclusions, Molecular genetic methods greatly improve the accuracy and resolution of identifications for invasive benthic marine amphipods at the species level and below. Our data suggest that multiple cryptic introductions of Ampithoe have occurred in the north-eastern Pacific and highlight uncertainty regarding the origin and invasion histories of both Jassa and Ampithoe species. Additional morphological and genetic analyses are necessary to clarify the taxonomy and native biogeography of both amphipod genera. [source] Early juvenile development of deep-sea asteroids of the NE Atlantic Ocean, with notes on juvenile bathymetric distributionsACTA ZOOLOGICA, Issue 1 2001Paulo Y. G. Sumida Abstract The postmetamorphic ontogenesis of 11 deep-sea asteroid species is described. Juvenile bathymetric distributions are compared to adults. The deep-sea juvenile asteroids of the NE Atlantic could be distinguished to species level from a very early stage of development. In all species, except Porcellanaster ceruleus and Plinthaster dentatus, the arms grow faster than the body. In Porcellanaster ceruleus and Plinthaster dentatus, early growth is nearly isometric. In the appearance of the epiproctal cone, the change in form of the furrow and apical spines, the early development of the cribriform organ adjacent to the madreporite and the appearance of sediment in the stomach indicate that Porcellanaster ceruleus is likely to undergo a shift in habitat and diet during the juvenile phase. Porcellanaster ceruleus is probably a predator on meiofauna and small macrofauna during the early stages of life, changing to a burrowing lifestyle ingesting sediment particles. Juvenile sea stars showed wider bathymetric distributions than their adult counterparts, suggesting that events occurring during the early stages of life are important for the maintenance of the local population structure and diversity in the deep NE Atlantic. [source] Size traits and site conditions determine changes in seed bank structure caused by grazing exclusion in semiarid annual plant communitiesECOGRAPHY, Issue 1 2006Yagil Osem 1. Contrasting patterns of change in the seed bank of natural grasslands are frequently found in response to grazing by domestic herbivores. Here, we studied the hypotheses that a) patterns of change in seed bank density and composition in response to grazing depend on spatial variation in resource availability and productivity, and b) that variation among species in patterns of seed bank response to grazing is linked to differences in species size traits (i.e. size of plant, dispersal unit and seed). 2. Effects of sheep grazing exclusion on the seed bank were followed during five years in a semiarid Mediterranean annual plant community in Israel. Seed bank density and composition were measured in autumn, before the rainy season, inside and outside fenced exclosures in four neighboring topographic sites differing in vegetation characteristics, soil resources and primary productivity: Wadi (dry stream terraces, high productive site), Hilltop, South- and North-facing slopes (less productive sites). 3. Topographic sites differed in seed density (range ca 2500,18000 seed m,2) and in seed bank response to grazing exclusion. Fencing increased seed density by 78, 51 and 18% in the Wadi, South- and North-facing slopes, respectively, but had no effect in the Hilltop. At the species level, grazing exclusion interacted with site conditions in determining species seed bank density, with larger or opposite changes in the high productive Wadi compared to the other less productive sites. 4. Changes in seed bank structure after grazing exclusion were strongly related to species size traits. Grazing exclusion favored species with large size traits in all sites, while seed density of tiny species decreased strongly in the high productive Wadi. Species with medium and small size traits showed lesser or no responses. 5. The size of plants, dispersal units and seeds were strongly correlated to each other, thus confounding the evaluation of the relative importance of each trait in the response of species to grazing and site conditions. We propose that the relative importance of plant size vs seed size in the response to grazing changes with productivity level. [source] The interpretation, assessment and conservation of ecological communitiesECOLOGICAL MANAGEMENT & RESTORATION, Issue 2009David A. Keith Summary Ecological communities are assemblages of species that occur together in space and time. Their properties include composition, structure, habitat, distribution, biological interactions and ecosystem functions. The community concept has a central role in conservation planning, and is a key approach for biodiversity conservation above the species level. The relatively recent application of risk assessment and regulatory systems to conservation of ecological communities has highlighted a number of challenges related to intrinsic uncertainties in the definition, diagnosis and assessment of ecological communities. In this review, I aim to elucidate some key conceptual issues essential to the interpretation of communities. Effective description, diagnosis and assessment of communities rests on an understanding of community theory in relation to environmental gradients and ecosystem dynamics. Continuum and discrete models can both contribute to interpretation of communities for conservation. Different sources of uncertainty are inherent in the key properties that characterize communities. Although some of these are reducible, remaining uncertainty must be incorporated into assessments and decision-making processes for conservation. Protocols for assessing extinction risks of communities address rates of decline in distribution, size of distribution and rates of decline in ecological functions. Some protocols assess these factors in a manner that may be inconsistent with equivalent methods for assessing species. Communities may be viewed in a framework that distinguishes thematic, spatial and temporal scales. These scales influence the outcomes of risk assessment, the benefits and limitations of maps and how well communities perform their function in conservation planning. When applied effectively, ecological communities can be powerful tools for delivering cost-effective outcomes for land-use planning and biodiversity conservation. [source] Development and experimental validation of a nifH oligonucleotide microarray to study diazotrophic communities in a glacier forefieldENVIRONMENTAL MICROBIOLOGY, Issue 8 2009Laurence Duc Summary Functional microarrays are powerful tools that allow the parallel detection of multiple strains at the species level and therefore to rapidly obtain information on microbial communities in the environment. However, the design of suitable probes is prone to uncertainties, as it is based so far on in silico predictions including weighted mismatch number and Gibbs free-energy values. This study describes the experimental selection of probes targeting subsequences of the nifH gene to study the community structure of diazotrophic populations present in Damma glacier (Swiss Central Alps) forefield soils. Using the Geniom® One in situ synthesis technology (Febit, Germany), 2727 in silico designed candidate probes were tested. A total of 946 specific probes were selected and validated. This probe set covered a large diversity of the NifH phylotypes (35 out of the 45) found in the forefield. Hybridization predictors were tested statistically. Gibbs free-energy value for probe-target binding gave the best prediction for hybridization efficiency, while the weighted mismatch number was not significantly associated to probe specificity. In this study, we demonstrate that extensive experimental tests of probe-hybridization behaviour against sequences present in the studied environment remain a prerequisite for meaningful probe selection. [source] Soils of a Mediterranean hot spot of biodiversity and endemism (Sardinia, Tyrrhenian Islands) are inhabited by pan-European, invasive species of Hypocrea/TrichodermaENVIRONMENTAL MICROBIOLOGY, Issue 1 2009Quirico Migheli Summary We have used a Mediterranean hot spot of biodiversity (the Island of Sardinia) to investigate the impact of abiotic factors on the distribution of species of the common soil fungus Trichoderma. To this end, we isolated 482 strains of Hypocrea/Trichoderma from 15 soils comprising undisturbed and disturbed environments (forest, shrub lands and undisturbed or extensively grazed grass steppes respectively). Isolates were identified at the species level by the oligonucleotide BarCode for Hypocrea/Trichoderma (TrichOKEY), sequence similarity analysis (Trichoblast) and phylogenetic inferences. The majority of the isolates were positively identified as pan-European and/or pan-global Hypocrea/Trichoderma species from sections Trichoderma and Pachybasium, comprising H. lixii/T. harzianum, T. gamsii, T. spirale, T. velutinum, T. hamatum, H. koningii/T. koningii, H. virens/T. virens, T. tomentosum, H. semiorbis, H. viridescens/T. viridescens, H. atroviridis/T. atroviride, T. asperellum, H. koningiopsis/T. koningiopsis and Trichoderma sp. Vd2. Only one isolate represented a new, undescribed species belonging to the Harzianum,Catoptron Clade. Internal transcribed spacer sequence analysis revealed only one potentially endemic internal transcribed spacer 1 allele of T. hamatum. All other species exhibited genotypes that were already found in Eurasia or in other continents. Only few cases of correlation of species occurrence with abiotic factors were recorded. The data suggest a strong reduction of native Hypocrea/Trichoderma diversity, which was replaced by extensive invasion of species from Eurasia, Africa and the Pacific Basin. [source] ON THE ADAPTIVE ACCURACY OF DIRECTIONAL ASYMMETRY IN INSECT WING SIZEEVOLUTION, Issue 11 2008Christophe Pélabon Subtle left,right biases are often observed in organisms with an overall bilateral symmetry. The evolutionary significance of these directional asymmetries remains uncertain, however, and scenarios of both developmental constraints and adaptation have been suggested. Reviewing the literature on asymmetry in insect wings, we analyze patterns of directional asymmetry in wing size to evaluate the possible adaptive significance of this character. We found that directional asymmetry in wing size is widespread among insects, with left- and right-biased asymmetries commonly observed. The direction of the asymmetry does not appear to be evolutionarily conserved above the species level. Overall, we argue that the very small magnitude of directional asymmetry, 0.7% of the wing size on average, associated with an extremely imprecise expression, precludes directional asymmetry from playing any major adaptive role. [source] THE LOCI OF EVOLUTION: HOW PREDICTABLE IS GENETIC EVOLUTION?EVOLUTION, Issue 9 2008David L. Stern Is genetic evolution predictable? Evolutionary developmental biologists have argued that, at least for morphological traits, the answer is a resounding yes. Most mutations causing morphological variation are expected to reside in the cis -regulatory, rather than the coding, regions of developmental genes. This "cis -regulatory hypothesis" has recently come under attack. In this review, we first describe and critique the arguments that have been proposed in support of the cis -regulatory hypothesis. We then test the empirical support for the cis -regulatory hypothesis with a comprehensive survey of mutations responsible for phenotypic evolution in multicellular organisms. Cis -regulatory mutations currently represent approximately 22% of 331 identified genetic changes although the number of cis -regulatory changes published annually is rapidly increasing. Above the species level, cis -regulatory mutations altering morphology are more common than coding changes. Also, above the species level cis -regulatory mutations predominate for genes not involved in terminal differentiation. These patterns imply that the simple question "Do coding or cis -regulatory mutations cause more phenotypic evolution?" hides more interesting phenomena. Evolution in different kinds of populations and over different durations may result in selection of different kinds of mutations. Predicting the genetic basis of evolution requires a comprehensive synthesis of molecular developmental biology and population genetics. [source] THE PHYLOGENETIC PATTERN OF SPECIATION AND WING PATTERN CHANGE IN NEOTROPICAL ITHOMIA BUTTERFLIES (LEPIDOPTERA: NYMPHALIDAE)EVOLUTION, Issue 7 2006Chris D. Jiggins Abstract Species level phylogenetic hypotheses can be used to explore patterns of divergence and speciation. In the tropics, speciation is commonly attributed to either vicariance, perhaps within climate-induced forest refugia, or ecological speciation caused by niche adaptation. Mimetic butterflies have been used to identify forest refugia as well as in studies of ecological speciation, so they are ideal for discriminating between these two models. The genus Ithomia contains 24 species of warningly colored mimetic butterflies found in South and Central America, and here we use a phylogenetic hypothesis based on seven genes for 23 species to investigate speciation in this group. The history of wing color pattern evolution in the genus was reconstructed using both parsimony and likelihood. The ancestral pattern for the group was almost certainly a transparent butterfly, and there is strong evidence for convergent evolution due to mimicry. A punctuationist model of pattern evolution was a significantly better fit to the data than a gradualist model, demonstrating that pattern changes above the species level were associated with cladogenesis and supporting a model of ecological speciation driven by mimicry adaptation. However, there was only one case of sister species unambiguously differing in pattern, suggesting that some recent speciation events have occurred without pattern shifts. The pattern of geographic overlap between clades over time shows that closely related species are mostly sympatric or, in one case, parapatric. This is consistent with modes of speciation with ongoing gene flow, although rapid range changes following allopatric speciation could give a similar pattern. Patterns of lineage accumulation through time differed significantly from that expected at random, and show that most of the extant species were present by the beginning of the Pleistocene at the latest. Hence Pleistocene refugia are unlikely to have played a major role in Ithomia diversification. [source] PHYLOGENETIC COMPARATIVE ANALYSIS OF LIFE-HISTORY VARIATION AMONG POPULATIONS OF THE LIZARD SCELOPORUS UNDULATUS:AN EXAMPLE AND PROGNOSISEVOLUTION, Issue 3 2004Peter H. Niewiarowski Abstract Over the past 15 years, phylogenetic comparative methods (PCMs) have become standard in the study of life-history evolution. To date, most studies have focused on variation among species or higher taxonomic levels, generally revealing the presence of significant phylogenetic effects as well as residual variation potentially attributable to adaptive evolution. Recently, population-level phylogenetic hypotheses have become available for many species, making it possible to apply PCMs directly to the level at which experiments are typically used to test adaptive hypotheses. In this study, we present the results of PCMs applied to life-history variation among populations of the widespread and well-studied lizard Sceloporus undulatus. Using S. undulatus (which may represent four closely related species) as an example, we explore the benefits of using PCMs at the population level, as well as consider the importance of several thorny methodological problems including but not limited to nonindependence of populations, lack of sufficient variation in traits, and the typically small sample sizes dictated by the difficulty of collecting detailed demographic data. We show that phylogenetic effects on life-history variation among populations of S. undulatus appear to be unimportant, and that several classic trade-offs expected by theory and revealed by many interspecific comparisons are absent. Our results suggest that PCMs applied to variation in life-history traits below the species level may be of limited value, but more studies like ours are needed to draw a general conclusion. Finally, we discuss several outstanding problems that face studies seeking to apply PCMs below the species level. [source] NONSTOCHASTIC VARIATION OF SPECIES-LEVEL DIVERSIFICATION RATES WITHIN ANGIOSPERMSEVOLUTION, Issue 3 2003Hallie J. Sims Abstract Variations in the origination and extinction rates of species over geological time often are linked with a range of factors, including the evolution of key innovations, changes in ecosystem structure, and environmental factors such as shifts in climate and physical geography. Before hypothesizing causality of a single factor, it is critical to demonstrate that the observed variation in diversification is significantly greater than one would expect due to natural stochasticity in the evolutionary branching process. Here, we use a likelihood-ratio test to compare taxonomic rate heterogeneity to a neutral birth-death model, using data on well-supported sister pairs of taxa and their species richness. We test the likelihood that the distribution of extant species among angiosperm genera and families could be the result of constant diversification rates. Results strongly support the conclusion that there is significantly more heterogeneity in diversity at the species level within angiosperms than would be expected due to stochastic processes. This result is consistent in datasets of genus pairs and family pairs and is not affected significantly by degrading pairs to simulate inaccuracy in the assumption of simultaneous origin of sister taxa. When we parse taxon pairs among higher groups of angiosperms, results indicate that a constant rates model is not rejected by rosid and basal eudicot pairs but is rejected by asterid and eumagnoliid pairs. These results provide strong support for the hypothesis that species-level rates of origination and/or extinction have varied nonrandomly within angiosperms and that the magnitude of heterogeneity varies among major groups within angiosperms. [source] DIVERGENCE WITH GENE FLOW IN THE ROCK-DWELLING CICHLIDS OF LAKE MALAWIEVOLUTION, Issue 5 2000Patrick D. Danley Abstract Within the past two million years, more than 450 species of haplochromine cichlids have diverged from a single common ancestor in Lake Malawi. Several factors have been implicated in the diversification of this monophyletic clade, including changes in lake level and low levels of gene flow across limited geographic scales. The objectives of this study were to determine the effect of recent lake-level fluctuations on patterns of allelic diversity in the genus Metriaclima, to describe the patterns of population structure within this genus, and to identify barriers to migration. This was accomplished through an analysis of allele frequencies at four microsatellite loci. Twelve populations spanning four species within Metriaclima were surveyed. The effect of lake-level fluctuations can be seen in the reduced genetic diversity of the most recently colonized sites; however, genetic diversity is not depressed at the species level. Low levels of population structure exist among populations, yet some gene flow persists across long stretches of inhospitable habitat. No general barrier to migration was identified. The results of this study are interpreted with respect to several speciation models. Divergence via population bottlenecks is unlikely due to the large allelic diversity observed within each species. Genetic drift and microallopatric divergence are also rejected because some gene flow does occur between adjacent populations. However, the reduced levels of gene flow between populations does suggest that minor changes in the selective environment could cause the divergence of populations. [source] Notes on South American Valerianaceae IIFEDDES REPERTORIUM, Issue 5-6 2004F. Weberling Professor em. Entre ValerianapotopensisBriq., descripta para Bolivia, y Valeriana humahuacensisBorsini, descripta para Jujuy, la provincia contigua de la Argentina, no se han encontrado características morfológicas para distinguir ambas especies, por eso éstas estarían unidas bajo del nombre ValerianapotopensisBriq. Por otra parte Valeriana bolivianaBritton y Valeriana bangianaGraebn., serían según Graebner (1906) dos especies distintas, pero no dió caracteres seguros para diferen-ciarlas. En este trabajo se observa que la forma de los frutos de los materiales tomados como tipo y paratipos es diferente, frutos ovados, como descripto para V. boliviana, se observan en unos paratipos, también se ven frutos ancho-ovados con un margen grueso, pero los del lectotipo V. boliviana (Rusby 871 NY) tienen un contorno casi circular como una lenteja, con un margen tenue, casi membranoso como los del lectotipo de V. bangiana (Bang 2415 G). Ni los caracteres vegetativos ni los caracteres de los frutos serían suficientes para poder distinguir V. bangianaGraebn. 1906 de V. bolivianaBritton 1891 como especies separadas. Se observa también que Valeriana variabilisGraebn. sería una forma de Valeriana warburgiiGraebn. La primera especie solo se distinguiría por caracteres poco manifiestos como el indumento de los frutos y los pelos frecuentemente se pierden durante de la maduración de los mismos, estos caracteres no serían suficientes para separar las dos especies. Por lo tanto se considera una nueva combinación, Valeriana warburgiiGraebn. subsp. variabilis(Graebn.) Weberling stat. nov. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) ValerianapotopensisBriq., described from Bolivia, and Valeriana humahuacensisBorsini, described from Jujuy, the neighbouring province of Argentina, cannot be distinguished by reliable distinctive characters. This applies especially to the indument of the fruits, since the fruits of Valeriana often become increasingly glabrescent in advanced stages of development, with the mature fruits being completely bald. Therefore both species should be united under the older name ValerianapotopensisBriq. According to Graebner (1906) Valeriana bangianaGraebn., is to be regarded as separate species, differing from Valeriana bolivianaBritton by its vigorous densely foliated stem, a character cer-tainly insufficient for a reliable identification. The fruits of V. boliviana are described as "ovatis", which is confirmed by the para-type material of the Mandon collections. In the paratypes the fruits were found to be lanceolate-ovate (Rusby872) or broadly ovate with prominent nerves and a thickened solid margin (Rusby875). However, the fruits of the holotype Rusby 871 (Fig. 12a, b) present a different shape: compressed fruits of nearly circular outline, with a broad flattened some-what membraneous marginal ring. The same form of fruits, although considerably larger, was found in the type material of Valeriana bangiana. Because of the overlapping of the vegetative characters as well as the forms of the fruits V. bangianaGraebn. 1906 cannot be clearly separated from V. bolivianaBritton 1891, and is included into this species. Valeriana warburgiiGraebn. and V. variabilisGraebn. too cannot be separated at species level because of over-lapping characters. Again the indumentum of the fruits is apparently according to several authors the best key character, but is not at all reliable. However, the outline of the fruits shows some differences. Therefore V. variabilis is included into V. warburgii as follows: V. warburgiiGraebn. subsp. variabilis(Graebn.) Weberling stat. nov. [source] Highly diverse community structure in a remote central Tibetan geothermal spring does not display monotonic variation to thermal stressFEMS MICROBIOLOGY ECOLOGY, Issue 1 2006Lau Chui Yim Abstract We report an assessment of whole-community diversity for an extremely isolated geothermal location with considerable phylogenetic and phylogeographic novelty. We further demonstrate, using multiple statistical analyses of sequence data, that the response of community diversity is not monotonic to thermal stress along a gradient of 52,83°C. A combination of domain- and division-specific PCR was used to obtain a broad spectrum of community phylotypes, which were resolved by denaturing gradient gel electrophoresis. Among 58 sequences obtained from microbial mats and streamers, some 95% suggest novel archaeal and bacterial diversity at the species level or higher. Moreover, new phylogeographic and thermally defined lineages among the Cyanobacteria, Chloroflexi, Eubacterium and Thermus are identified. Shannon,Wiener diversity estimates suggest that mats at 63°C supported highest diversity, but when alternate models were applied [Average Taxonomic Distinctness (AvTD) and Variation in Taxonomic Distinctness (VarTD)] that also take into account the phylogenetic relationships between phylotypes, it is evident that greatest taxonomic diversity (AvTD) occurred in streamers at 65,70°C, whereas greatest phylogenetic distance between taxa (VarTD) occurred in streamers of 83°C. All models demonstrated that diversity is not related to thermal stress in a linear fashion. [source] Trichoderma biodiversity in China: Evidence for a North to South distribution of species in East AsiaFEMS MICROBIOLOGY LETTERS, Issue 2 2005Chu-long Zhang Abstract Towards assessing the biodiversity and biogeography of Trichoderma, we have analyzed the occurrence of Trichoderma species in soil and litter from four areas in China: North (Hebei province), South-East (Zhejiang province), West (Himalayan, Tibet) and South-West (Yunnan province). One hundred and thirty five isolates were grouped according to tentative morphological identification. A representative 64 isolates were verified at the species level by the oligonucleotide barcode program TrichO Key v.1.0 and the custom BLAST server Tricho BLAST, using sequences of the ITS1 and 2 region of the rRNA cluster and from the longest intron of the tef1 (translation elongation factor 1-,) gene. Eleven known species (Trichoderma asperellum, T. koningii, T. atroviride, T. viride, T. velutinum, T. cerinum, T. virens, T. harzianum, T. sinensis, T. citrinoviride, T. longibrachiatum) and two putative new species (T. sp. C1, and T. sp. C2), distinguished from known species both by morphological characters and phylogenetic analysis, were identified. A significant difference in the occurrence of these species was found between the North (Hebei) and South-West (Yunnan) areas, which correlates with previously reported species distributions in Siberia and South-East Asia, respectively. As in previous studies, T. harzianum accounted for almost half of the biodiversity; although, in this study, it was exclusively found in the North, and was predominantly represented by an ITS1 and 2 haplotype, which has so far been rarely found elsewhere. This study therefore reveals a North,South gradient in species distribution in East Asia, and identifies Northern China as a potential center of origin of a unique haplotype of T. harzianum. [source] The use of killer sensitivity patterns for biotyping yeast strains: the state of the art, potentialities and limitationsFEMS YEAST RESEARCH, Issue 6 2007Pietro Buzzini Abstract In recent years molecular techniques have been the most useful tools for the unequivocal identification of undetermined strains at the species level. In many instances, however, a further discrimination at the strain level (biotyping) is required, such as during epidemiological investigations, in which the distribution of pathogenic microorganisms is studied, and for patent protection purposes. Although molecular methods are routinely used also for yeast biotyping, several nonmolecular techniques have been proposed. One of these, the determination of the killer sensitivity pattern (KSP) towards a panel of selected killer toxins has proven to be a good auxiliary method. Despite the plethora of studies published, the potential and limitations of the determination of KSPs have never been critically evaluated. In this review the use of this nonmolecular technique as a biotyping tool is discussed and compared with some currently used DNA-based procedures. In addition, methodological, mechanistic and ecological implications are evaluated. [source] Factors influencing fish catch levels on Kenya's coral reefsFISHERIES MANAGEMENT & ECOLOGY, Issue 4 2007S. C. Mangi Abstract, The factors influencing fish catches on Kenya's coral reefs were studied. Catch data were collected at the species level by counting the number of fish landed at each landing site of each fishing ground. Live coral cover, topographic complexity, fish and sea urchin density, and the number of fishers and gear units used in each fishing ground were compared with catch data. Fishing grounds included one location where only basket traps were allowed, six locations where all gear types were used except beach seines, and three locations where all types of gear, including beach seines, were used. Catch and effort variables were similar across the fishing grounds whereas live coral cover and sea urchin density differed (P < 0.01). The sites fished by all types of gear including beach seines had the lowest coral cover (8.4 ± 0.9%) and topographic complexity (1.12 ± 0.01). Catch levels were positively correlated with the number of fishers and fish density but not with the number of gear units deployed or sea urchin density. The number of fishers and live coral cover were the strongest factors determining total catch levels. The results suggest that high levels of fishing effort coupled with the use of destructive gear types, exacerbate the effects of overfishing on Kenya's reefs. [source] Copepod species diversity and climate variability in the tropical Atlantic OceanFISHERIES OCEANOGRAPHY, Issue 4-5 2003Sergey A. Piontkovski Abstract A database synthesized from 19 oceanographic expeditions conducted by the former Soviet Union was used to analyse interannual patterns in copepod species diversity in the tropical Atlantic. Mesozooplankton was collected predominately in vertical hauls through the upper 100 m with Juday nets. The samples from 744 oceanographic stations were identified and enumerated to the species level. To assess species diversity, the Shannon diversity index was used. On the interdecadal scale, no statistically confirmed trend was found in species diversity change over the years sampled (1963,89). Multiple regression analysis indicated that interannual fluctuations of the South Atlantic High (pressure and latitude), the Azores High longitude and El Niño,Southern Oscillation (ENSO) index could explain 87% of species diversity fluctuations. Possible mechanisms that drive interannual fluctuations of species diversity are discussed. [source] Fore limb bones of late Pleistocene dwarf hippopotamuses (Mammalia, Cetartiodactyla) from Madagascar previously determined as belonging to the crocodylid Voay Brochu, 2007FOSSIL RECORD-MITTEILUNGEN AUS DEM MUSEUM FUER NATURKUNDE, Issue 2 2010Oliver Hampe Abstract A humerus and two radii of juvenile dwarf hippopotamuses are redescribed. The subfossil bones from the collection of the Museum für Naturkunde Berlin were erroneously assigned to the horned crocodile Voay robustus (Grandidier & Vaillant, 1872) by Bickelmann & Klein (2009). All three limb bones presented here belong to immature animals. The epiphyses are not fused, except the proximal extremity of the right radius; and the radius and ulna are also unfused. The two radii are from individuals of different size, whereas the left radius and the humerus are from animals of similar size. Morphologically, the limb bones cannot be identified to species level. A tentative assignment to Hippopotamus madagascariensis is discussed based on the knowledge of the geographic origin on the island. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Invasions and niche width: does niche width of an introduced crayfish differ from a native crayfish?FRESHWATER BIOLOGY, Issue 8 2009KARIN OLSSON Summary 1. Human activities have promoted the spread of species worldwide. Several crayfish species have been introduced into new areas, posing a threat to native crayfish and other biota. Invader success may depend on the ability to utilise a wide variety of habitats and resources. Successful invaders are generally expected to have broader niches and to be more plastic than non-invasive species. 2. Using stable isotope ratios of carbon and nitrogen we compared the niche widths of native noble crayfish and introduced signal crayfish, a successful invader of Swedish streams. The calculation of niche width took account of between-site differences in basal resource isotope signature ranges. We also assessed whether population density, prey biomass or prey diversity affected niche width. 3. At the species level, signal crayfish had twice the niche width of noble crayfish. However, individual populations of noble crayfish and signal crayfish in Swedish streams had similar niche widths. This suggests that signal crayfish has greater plasticity with respect to habitat utilisation and feeding than noble crayfish. Niche width in both species correlated positively with benthic invertebrate biomass and diversity, indicating that animal food sources are important for crayfish. 4. We find that assessing niche width in relation to invader success can be a useful tool trying to predict the impact of invasions on different scales. The findings in this study suggest that invaders and natives will have a similar impact on the stream scale whereas the invader will have a larger impact on the regional scale due to the ability to utilise a wider range of streams. [source] Existing in plenty: abundance, biomass and diversity of ciliates and meiofauna in small streamsFRESHWATER BIOLOGY, Issue 4 2008JULIA REISS Summary 1. The ciliate and metazoan meiofaunal assemblages of two contrasting lowland streams in south-east England were examined over the period of a year, using a high taxonomic resolution. Monthly samples were taken from an oligotrophic, acid stream (Lone Oak) and a circumneutral, nutrient-rich stream (Pant) between March 2003 and February 2004. 2. We assessed the relative importance of ciliates and rotifers within the small-sized benthic assemblage with respect to their abundance, biomass and species richness. In addition, we examined the influence of abiotic and biotic parameters and season on the assemblage composition at two levels of taxonomic resolution (species and groups). 3. Ciliates dominated the assemblages numerically, with maximum densities of over 900 000 and 6 000 000 ind. m,2 in Lone Oak and Pant respectively. Rotifers and nematodes dominated meiofaunal densities, although their contribution to total meiofaunal biomass (maxima of 71.9 mgC m,2 in Lone Oak and of 646.8 mgC m,2 in the Pant) was low and rotifer biomass equalled that of ciliates. 4. Although the two streams differed in terms of total abundance of ciliates and meiofauna and shared only 7% of species, the relative proportion of groups was similar. Sediment grain size distribution (the percentile representing the 0.5,1 mm fraction) was correlated with assemblage structure at the species level, revealing the tight coupling between these small organisms and their physical environment. Seasonal changes in the relative abundance of groups followed similar patterns in both streams, and were correlated with the abundance of cyclopoid copepods and temperature. 5. Information on these highly abundant but often overlooked faunal groups is essential for estimates of overall abundance, biomass, species richness and productivity in the benthos, and as such has important implications for several areas of aquatic research, e.g. for those dealing with trophic dynamics. [source] Modelling the hydraulic preferences of benthic macroinvertebrates in small European streamsFRESHWATER BIOLOGY, Issue 1 2007SYLVAIN DOLÉDEC Summary 1. Relating processes occurring at a local scale to the natural variability of ecosystems at a larger scale requires the design of predictive models both to orientate stream management and to predict the effects of larger scale disturbances such as climate changes. Our study contributes to this effort by providing detailed models of the hydraulic preferences of 151 invertebrate taxa, mostly identified at the species level. We used an extensive data set comprising 580 invertebrate samples collected using a Surber net from nine sites of second and third order streams during one, two or three surveys at each site. We used nested non-linear mixed models to relate taxon local densities to bed shear stresses estimated from FliesswasserStammTisch hemisphere numbers. 2. An average model by taxon, i.e. independent from surveys, globally explained 25% of the density variations of taxa within surveys. A quadratic relationship existed between the average preferences and the niche breadth of taxa, indicating that taxa preferring extreme hemisphere numbers had a reduced hydraulic niche breadth. A more complete model, where taxa preferences vary across surveys, globally explained 38% of the variation of taxa densities within surveys. Variations in preferences across surveys were weak for taxa preferring extreme hemisphere numbers. 3. There was a significant taxonomic effect on preferences computed from the complete model. By contrast, season, site, average hemisphere number within a survey and average density of taxa within a survey used as covariates did not consistently explain shifts in taxon hydraulic preferences across surveys. 4. The average hydraulic preferences of taxa obtained from the extensive data set were well correlated to those obtained from two additional independent data sets collected in other regions. The consistency of taxon preferences across regions supports the use of regional preference curves for estimating the impact of river management on invertebrate communities. By contrast, the hydraulic niche breadths of taxa computed from the different data sets were not related. [source] Biodiversity on land and in the seaGEOLOGICAL JOURNAL, Issue 3-4 2001Michael J. Benton Abstract Life on land today is as much as 25 times as diverse as life in the sea. Paradoxically, this extraordinarily high level of continental biodiversity has been achieved in a shorter time and it occupies a much smaller area of the Earth's surface than does marine biodiversity. Raw palaeontological data suggest very different models for the diversification of life on land and in the sea. The well-studied marine fossil record appears to show evidence for an equilibrium model of diversification, with phases of rapid radiation, followed by plateaux that may indicate times of equilibrium diversity. The continental fossil record shows exponential diversification from the Silurian to the present. These differences appear to be real: the continental fossil record is unlikely to be so poor that all evidence for a high initial equilibrial diversity has been lost. In addition, it is not clear that the apparently equilibrial marine model is correct, since it is founded on studies at familial level. At species level, a logistic family-level curve probably breaks down to an exponential. The rocketing diversification rates of flowering plants, insects, and other land life are evidently hugely different from the more sluggish rates of diversification of life in the sea, perhaps as a result of greater endemism and habitat complexity on land. Copyright © 2001 John Wiley & Sons, Ltd. [source] Reduced early growing season freezing resistance in alpine treeline plants under elevated atmospheric CO2GLOBAL CHANGE BIOLOGY, Issue 3 2010MELISSA MARTIN Abstract The frequency of freezing events during the early growing season and the vulnerability to freezing of plants in European high-altitude environments could increase under future atmospheric and climate change. We tested early growing season freezing sensitivity in 10 species, from four plant functional types (PFTs) spanning three plant growth forms (PGFs), from a long-term in situ CO2 enrichment (566 vs. 370 ppm) and 2-year soil warming (+4 K) experiment at treeline in the Swiss Alps (Stillberg, Davos). By additionally tracking plant phenology, we distinguished indirect phenology-driven CO2 and warming effects from direct physiology-related effects on freezing sensitivity. The freezing damage threshold (lethal temperature 50) under ambient conditions of the 10 treeline species spanned from ,6.7±0.3 °C (Larix decidua) to ,9.9±0.6 °C (Vaccinium gaultherioides). PFT, but not PGF, explained a significant amount of this interspecific variation. Long-term exposure to elevated CO2 led to greater freezing sensitivity in multiple species but did not influence phenology, implying that physiological changes caused by CO2 enrichment were responsible for the effect. The elevated CO2 effect on freezing resistance was significant in leaves of Larix, Vaccinium myrtillus, and Gentiana punctata and marginally significant in leaves of Homogyne alpina and Avenella flexuosa. No significant CO2 effect was found in new shoots of Empetrum hermaphroditum or in leaves of Pinus uncinata, Leontodon helveticus, Melampyrum pratense, and V. gaultherioides. Soil warming led to advanced leaf expansion and reduced freezing resistance in V. myrtillus only, whereas Avenella showed greater freezing resistance when exposed to warming. No effect of soil warming was found in any of the other species. Effects of elevated CO2 and soil warming on freezing sensitivity were not consistent within PFTs or PGFs, suggesting that any future shifts in plant community composition due to increased damage from freezing events will likely occur at the individual species level. [source] Long-term changes in the abundance of flying insectsINSECT CONSERVATION AND DIVERSITY, Issue 4 2009CHRIS R. SHORTALL Abstract., 1.,For the first time, long-term changes in total aerial insect biomass have been estimated for a wide area of Southern Britain. 2.,Various indices of biomass were created for standardised samples from four of the Rothamsted Insect Survey 12.2 m tall suction traps for the 30 years from 1973 to 2002. 3.,There was a significant decline in total biomass at Hereford but not at three other sites: Rothamsted, Starcross and Wye. 4.,For the Hereford samples, many insects were identified at least to order level, some to family or species level. These samples were then used to investigate the taxa involved in the decline in biomass at Hereford. 5.,The Hereford samples were dominated by large Diptera, particularly Dilophus febrilis, which showed a significant decline in abundance. 6.,Changes in agricultural practice that could have contributed to the observed declines are discussed, as are potential implications for farmland birds, with suggestions for further work to investigate both cause and effect. [source] Insights into the termite assemblage of a neotropical rainforest from the spatio-temporal distribution of flying alatesINSECT CONSERVATION AND DIVERSITY, Issue 3 2009THOMAS BOURGUIGNON Abstract., 1. During the last decade, many studies have focused on the diversity of termite species and their ecological function, but these have been mostly based on transect protocols not designed to sample canopy-dwelling and subterranean species. Additionally, all these studies relied upon collections of foraging parties composed of workers and soldiers in the soil or in pieces of wood. 2. We hypothesised that alate-based protocols could disclose spatial and temporal patterns of termite flights and provide a more balanced picture of assemblages for ecological and biodiversity surveys. 3. Our study took place in the framework of the IBISCA-Panama project, which used numerous trapping methods to give a multifaceted overview of a complex tropical rainforest arthropod community. Two methods, flight interception traps and light traps, were efficient at collecting termite alates. All collected specimens were assigned to morphospecies which were later identified to the genus or species level, when possible. 4. Our results highlighted that: (i) alate trapping represents a powerful complement to ground-based standardised sampling protocols by allowing the documentation of the whole termite assemblage. (ii) Canopy dwellers fly preferentially in the upper strata, whereas no vertical stratification was found for ground dwellers, suggesting that height of flight is dictated by a pressure for long distance dispersal as well as the need to find a suitable site for colony-founding. (iii) Alates from closely related species do not stagger their flight period to avoid hybridisation but rather synchronise their flights according to environmental factors. [source] Phylogenetic analyses of marine sponges within the order Verongida: a comparison of morphological and molecular dataINVERTEBRATE BIOLOGY, Issue 3 2007Patrick M. Erwin Abstract. Because the taxonomy of marine sponges is based primarily on morphological characters that can display a high degree of phenotypic plasticity, current classifications may not always reflect evolutionary relationships. To assess phylogenetic relationships among sponges in the order Verongida, we examined 11 verongid species, representing six genera and four families. We compared the utility of morphological and molecular data in verongid sponge systematics by comparing a phylogeny constructed from a morphological character matrix with a phylogeny based on nuclear ribosomal DNA sequences. The morphological phylogeny was not well resolved below the ordinal level, likely hindered by the paucity of characters available for analysis, and the potential plasticity of these characters. The molecular phylogeny was well resolved and robust from the ordinal to the species level. We also examined the morphology of spongin fibers to assess their reliability in verongid sponge taxonomy. Fiber diameter and pith content were highly variable within and among species. Despite this variability, spongin fiber comparisons were useful at lower taxonomic levels (i.e., among congeneric species); however, these characters are potentially homoplasic at higher taxonomic levels (i.e., between families). Our molecular data provide good support for the current classification of verongid sponges, but suggest a re-examination and potential reclassification of the genera Aiolochroia and Pseudoceratina. The placements of these genera highlight two current issues in morphology-based sponge taxonomy: intermediate character states and undetermined character polarity. [source] Population stability in salmon species: effects of population size and female reproductive allocationJOURNAL OF ANIMAL ECOLOGY, Issue 5 2003Sigurd Einum Summary 1Population stability (i.e. level of temporal variation in population abundance) is linked commonly to levels of environmental disturbances. However, populations may also differ in their propensity to dampen or amplify the effects of exogenous forces. Here time-series of population estimates were used to test for such differences among 104 populations of six salmon species. 2At the species level, Atlantic (Salmo salar L.), chinook (Oncorhynchus tshawytscha Walbaum) and coho salmon (O. kisutch W) were less variable than sockeye (O. nerka W) and pink salmon (O. gorbuscha W). Chum salmon (O. keta W) was more similar to sockeye and pink salmon. These differences may be related in part to differences in body size, and hence susceptibility to adverse environmental conditions, at the time when they migrate to the sea or lakes. 3At the population level no effect of fecundity on variability was found, in contrast to findings for marine fishes, nor of egg size. Whereas substantial differences in the temporal stability of environmental factors among geographically close populations may over-ride any effects of fecundity or egg size in fresh water, this is less likely in the marine environment where spatial autocorrelations of environmental variability are more pronounced. 4Variation in population sizes was related positively to the duration of time-series when using standard deviations of ln-transformed population estimates, and also when using linearly detrended population variation, suggesting non-linear long-term abundance trends in salmon populations that extend beyond the 7-year period of the shortest time-series. 5When controlling for differences among species, stability increased with increasing population size, and it is hypothesized that this is due to large populations having a more complex spatial and genetic structure than small populations due to wider spatial distribution. The effects of population size on stability, as well as differences in stability among species, suggest that population- and organism-specific characteristics may interact with exogenous forces to shape salmon population dynamics. [source] Breeding bird species diversity in the Negev: effects of scrub fragmentation by planted forestsJOURNAL OF APPLIED ECOLOGY, Issue 5 2001Eyal Shochat Summary 1Afforestation of the Northern Negev, Israel, from 1956 resulted in patches of primarily coniferous trees that fragmented large scrubland areas. This alteration in landscape pattern was followed by immigration of mediterranean bird species to the Negev. 2We counted breeding birds, and measured various environmental variables in scrubland and planted forest patches, to test whether bird assemblages were random subsets of the regional species pool, and whether area or habitat structure was the major correlate with species abundance and distribution. 3Of 22 bird species recorded, only three appeared in both scrub and forest, showing that these two habitats were occupied by different species assemblages. In both habitats, species richness increased with area at a rate greater than that expected by random sampling. In the scrub this increase was related to area per se, while in the forest it was related to habitat diversity in terms of stand age and tree type. 4The density of forest species was unaffected by area, but specialist scrubland species declined as area decreased. We suggest that edge effects might reduce species abundance in small scrubland patches. 5Nested subset analysis indicated that, at the community level, species composition was not random. However, at the species level, the distribution of three forest-dwelling species appeared as random, as it was associated with habitat rather than with patch size. 6Our results indicate that increased diversity of breeding birds in the Northern Negev will require scrub patches larger than 50 ha among the increasingly forested landscape. In contrast, increasing forest area would hardly increase species diversity in the whole landscape. Future forest management regimes should also aim to increase habitat diversity by adding foliage layers, especially in the understorey. Exotic coniferous forests support fewer species than deciduous forests in mediterranean zones around the world. The suggested management regime may improve such forests as habitat for species-rich bird communities. [source] | |||||||||||||||||||||||||||||||||||||||||||