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Taxonomic Composition (taxonomic + composition)
Selected AbstractsPatterns of spatial autocorrelation of assemblages of birds, floristics, physiognomy, and primary productivity in the central Great Basin, USADIVERSITY AND DISTRIBUTIONS, Issue 3 2006Erica Fleishman ABSTRACT We fitted spatial autocorrelation functions to distance-based data for assemblages of birds and for three attributes of birds' habitats at 140 locations, separated by up to 65 km, in the Great Basin (Nevada, USA). The three habitat characteristics were taxonomic composition of the vegetation, physical structure of the vegetation, and a measure of primary productivity, the normalized difference vegetation index, estimated from satellite imagery. We found that a spherical model was the best fit to data for avifaunal composition, vegetation composition, and primary productivity, but the distance at which spatial correlation effectively was zero differed substantially among data sets (c. 30 km for birds, 20 km for vegetation composition, and 60 km for primary productivity). A power-law function was the best fit to data for vegetation structure, indicating that the structure of vegetation differed by similar amounts irrespective of distance between locations (up to the maximum distance measured). Our results suggested that the spatial structure of bird assemblages is more similar to vegetation composition than to either vegetation structure or primary productivity, but is autocorrelated over larger distances. We believe that the greater mobility of birds compared with plants may be responsible for this difference. [source] Benthic macroinvertebrates in Swedish streams: community structure, taxon richness, and environmental relationsECOGRAPHY, Issue 3 2003Leonard Sandin Spatial scale, e.g. from the stream channel, riparian zone, and catchment to the regional and global scale is currently an important topic in running water management and bioassessment. An increased knowledge of how the biota is affected by human alterations and management measures taken at different spatial scales is critical for improving the ecological quality of running waters. However, more knowledge is needed to better understand the relationship between environmental factors at different spatial scales, assemblage structure and taxon richness of running water organisms. In this study, benthic macroinvertebrate data from 628 randomly selected streams were analysed for geographical and environmental relationships. The dataset also included 100 environmental variables, from local measures such as in-stream substratum and vegetation type, catchment vegetation and land-use, and regional variables such as latitude and longitude. Cluster analysis of the macroinvertebrate data showed a continuous gradient in taxonomic composition among the cluster groups from north to south. Both locally measured variables (e.g. water chemistry, substratum composition) and regional factors (e.g. latitude, longitude, and an ecoregional delineation) were important for explaining the variation in assemblage structure and taxon richness for stream benthic macroinvertebrates. This result is of importance when planning conservation and management measurements, implementing large-scale biomonitoring programs, and predicting how human alterations (e.g. global warming) will affect running water ecosystems. [source] Diet dynamics of the juvenile piscivorous fish community in Spirit Lake, Iowa, USA, 1997,1998ECOLOGY OF FRESHWATER FISH, Issue 4 2001M. E. Pelham Abstract , We assessed temporal dynamics and variation among species and age-classes in the diets of age 0 and age 1 piscivorous fish species in Spirit Lake, Iowa, USA during 1997 and 1998. Species included walleye Stizostedion vitreum, yellow perch Perca flavescens, smallmouth bass Micropterus dolomieui, largemouth bass Micropterus salmoides, black crappie Pomoxis nigromaculatus and white bass Morone chrysops. Thirty taxa were identified in diets, including 12 species of fish. We found dramatic differences in diets among species, among age-classes within species and over time. Walleye, largemouth bass, smallmouth bass and white bass were piscivorous at age 0. Black crappie began piscivory at age 1. Yellow perch also began piscivory at age 1, but fish were a very small fraction of age-1 diets. The primary temporal pattern, seen in several species and age-classes, was an increase in piscivory from spring to fall. This pattern was due to the lack of small, age-0 prey fish in spring. Although some patterns were evident, the taxonomic composition of the diets of all species was highly variable over time, making generalizations difficult. A surprising result was the absence of yellow perch in the diet of age-0 walleye, despite their abundance in Spirit Lake and prominence in diets of age-1 walleye and other age 1-piscivores. Age-0 yellow perch were consistently too large to be eaten by age-0 piscivores, which preyed primarily on invertebrates and smaller fish such as johnny darters Etheostoma nigrum and age 0 bluegill Lepomis macrochirus. This finding suggests that predator-prey interactions and resulting population dynamics may be quite different in Spirit Lake than in other systems dominated by walleye and yellow perch., [source] Detection of microbial biomass by intact polar membrane lipid analysis in the water column and surface sediments of the Black SeaENVIRONMENTAL MICROBIOLOGY, Issue 10 2009Florence Schubotz Summary The stratified water column of the Black Sea produces a vertical succession of redox zones, stimulating microbial activity at the interfaces. Our study of intact polar membrane lipids (IPLs) in suspended particulate matter and sediments highlights their potential as biomarkers for assessing the taxonomic composition of live microbial biomass. Intact polar membrane lipids in oxic waters above the chemocline represent contributions of bacterial and eukaryotic photosynthetic algae, while anoxygenic phototrophic bacteria and sulfate-reducing bacteria comprise a substantial amount of microbial biomass in deeper suboxic and anoxic layers. Intact polar membrane lipids such as betaine lipids and glycosidic ceramides suggest unspecified anaerobic bacteria in the anoxic zone. Distributions of polar head groups and core lipids show planktonic archaea below the oxic zone; methanotrophic archaea are only a minor fraction of archaeal biomass in the anoxic zone, contrasting previous observations based on the apolar derivatives of archaeal lipids. Sediments contain algal and bacterial IPLs from the water column, but transport to the sediment is selective; bacterial and archaeal IPLs are also produced within the sediments. Intact polar membrane lipid distributions in the Black Sea are stratified in accordance with geochemical profiles and provide information on vertical successions of major microbial groups contributing to suspended biomass. This study vastly extends our knowledge of the distribution of complex microbial lipids in the ocean. [source] Metagenomic approach studying the taxonomic and functional diversity of the bacterial community in a mesotrophic lake (Lac du Bourget , France)ENVIRONMENTAL MICROBIOLOGY, Issue 9 2009Didier Debroas Summary The main goals of this work were to identify the metabolic pathways of the bacterial community in a lacustrine ecosystem and to establish links between taxonomic composition and the relative abundances of these metabolic pathways. For this purpose, we analysed a 16S rRNA gene library obtained by gene amplification together with a sequence library of both insert ends on c. 7700 fosmids. Whatever the library used, Actinobacteria was the most abundant bacterial group, followed by Proteobacteria and Bacteroidetes. Specific aquatic clades such as acI and acIV (Actinobacteria) or LD12 and GOBB-C201 (Alphaproteobacteria) were found in both libraries. From comparative analysis of metagenomic libraries, the metagenome of this lake was characterized by overrepresentation of genes involved in the degradation of xenobiotics mainly associated with Alphaproteobacteria. Actinobacteria were mainly related to metabolic pathways involved in nucleotide metabolism, cofactors, vitamins, energy, replication and repair. Betaproteobacteria appeared to be characterized by the presence of numerous genes implicated in environmental information processing (membrane transport and signal transduction) whereas glycan and carbohydrate metabolism pathways were overrepresented in Bacteroidetes. These results prompted us to propose hypotheses on the ecological role of these bacterial classes in lacustrine ecosystems. [source] Diversity of planktonic photoautotrophic microorganisms along a salinity gradient as depicted by microscopy, flow cytometry, pigment analysis and DNA-based methodsFEMS MICROBIOLOGY ECOLOGY, Issue 2 2004Marta Estrada Abstract The diversity of prokaryotic and eukaryotic phytoplankton was studied along a gradient of salinity in the solar salterns of Bras del Port in Santa Pola (Alacant, Spain) using different community descriptors. Chlorophyll a, HPLC pigment composition, flow cytometrically-determined picoplankton concentration, taxonomic composition of phytoplankton (based on optical microscopy) and genetic fingerprint patterns of 16S (cyanobacteria- and chloroplast-specific primers) and 18S rRNA genes were determined for samples from ponds with salinities ranging from 4% to 37%. Both morphological and genetical descriptors of taxonomic composition showed a good agreement and indicated a major discontinuity at salinities between 15% and 22%. The number of classes and the Shannon diversity index corresponding to the different descriptors showed a consistent decreasing trend with increasing salinity. The results indicate a selective effect of extremely high salinities on phytoplanktonic assemblages. [source] How well can the fatty acid content of lake seston be predicted from its taxonomic composition?FRESHWATER BIOLOGY, Issue 9 2010A. BEC Abstract 1. Results from the few field studies that have tried to relate seston taxonomic and fatty acid (FA) composition suggest that phytoplankton composition only partially explains seston FA composition. However, in these studies, the heterotrophic components of seston (i.e. bacteria and heterotrophic protists) have not been accounted for. 2. The general premise of this article was that including the contribution of heterotrophs to seston biomass can improve understanding of the variability in seston FA composition. This was tested for an oligotrophic clearwater lake, in which the taxonomic and FA compositions of seston, fractionated into three size classes, were monitored every 2 weeks over a growth season. The relationship between seston taxonomic and FA composition was studied using canonical correlation analyses. 3. Because of their relative richness in branched FA and lack of highly unsaturated FAs (HUFA) compared to autotrophs and other protists, the contribution of bacteria to seston biomass was shown to explain an important part of the differences in FA composition between the different seston size classes. Phytoplankton seasonal succession also affected the FA composition of seston but only for size classes that were dominated by autotrophs. 4. The results also indicated that heterotrophic protists such as ciliates and heterotrophic nanoflagellates might substantially influence the seston FA, and especially, HUFA, composition. 5. The per cent of variability in seston FA composition that was explained by its taxonomic composition was still relatively low, even when taking account of heterotrophs. Hence, other possible influences, such as phytoplankton species composition, physiological state and the contribution of terrestrial detritus, need investigation. [source] Similar breakdown rates and benthic macroinvertebrate assemblages on native and Eucalyptus globulus leaf litter in Californian streamsFRESHWATER BIOLOGY, Issue 4 2010IGOR LA Summary 1.,Eucalyptus globulus, a tree species planted worldwide in many riparian zones, has been reported to affect benthic macroinvertebrates negatively. Although there is no consensus about the effects of Eucalyptus on aquatic macrobenthos, its removal is sometimes proposed as a means of ecological restoration. 2.,We combined the sampling of macroinvertebrates with measurement of the colonisation of leaf packs in mesh bags, to examine the effects of riparian Eucalyptus and its litter on benthic macroinvertebrates in three small streams in California, U.S.A. Each stream included one reach bordered by Eucalyptus (E-site) and a second bordered by native vegetation (N-site). 3.,The macrobenthos was sampled and two sets of litter bags were deployed at each site: one set with Eucalyptus litter (Euc-bags) and one with mixed native tree litter (Nat-bags) containing Quercus, Umbellularia, Acer and Alnus. Bags were exposed for 28, 56 and 90 days and this experiment was repeated in the autumn, winter and spring to account for effects of changing stream flow and insect phenology. 4.,Litter input (average dry mass: 950 g m,2 year,1 in E-sites versus 669 g m,2 year,1 in N-sites) was similar, although in-stream litter composition differed between E- and N-sites. Litter broke down at similar rates in Euc-bags and Nat-bags (0.0193 day,1 versus 0.0134 day,1), perhaps reflecting the refractory nature of some of the leaves of the native trees (Quercus agrifolia). 5.,Summary metrics for macroinvertebrates (taxon richness, Shannon diversity, pollution tolerance index) did not differ significantly between the E and N sites, or between Euc-bags and Nat-bags. No effect of exposure time or site was detected by ordination of the taxa sampled. However, distinct seasonal ordination clusters were observed in winter, spring and autumn, and one of the three streams formed a separate cluster. 6.,The presence of Eucalyptus was less important in explaining the taxonomic composition of the macrobenthos than either ,season' or ,stream'. Similarly, these same two factors (but not litter species) also helped explain the variation in leaf breakdown. We conclude that patches of riparian Eucalyptus and its litter have little effect on stream macrobenthos in this region. [source] Spatial scale and the diversity of macroinvertebrates in a Neotropical catchmentFRESHWATER BIOLOGY, Issue 2 2010RAPHAEL LIGEIRO Summary 1.,Lotic ecosystems can be studied on several spatial scales, and usually show high heterogeneity at all of them in terms of biological and environmental characteristics. Understanding and predicting the taxonomic composition of biological communities is challenging and compounded by the problem of scale. Additive diversity partitioning is a tool that can show the diversity that occurs at different scales. 2.,We evaluated the spatial distribution of benthic macroinvertebrates in a tropical headwater catchment (S.E. Brazil) during the dry season and compared alpha and beta diversities at the scales of stream segments, reaches, riffles and microhabitats (substratum types: gravels, stones and leaf litter). We used family richness as our estimate of diversity. Sampling was hierarchical, and included three stream segments, two stream reaches per segment, three riffles per reach, three microhabitats per riffle and three Surber sample units per microhabitat. 3.,Classification analysis of the 53 families found revealed groups formed in terms of stream segment and microhabitat, but not in terms of stream reaches and riffles. Separate partition analyses for each microhabitat showed that litter supported lower alpha diversity (28%) than did stones (36%) or gravel (42%). In all cases, alpha diversity at the microhabitat scale was lower than expected under a null model that assumed no aggregation of the fauna. 4.,Beta diversity among patches of the microhabitats in riffles depended on substratum type. It was lower than expected in litter, similar in stone and higher in gravel. Beta diversities among riffles and among reaches were as expected under the null model. On the other hand, beta diversity observed was higher than expected at the scale of stream segments for all microhabitat types. 5., We conclude that efficient diversity inventories should concentrate sampling in different microhabitats and stream sites. In the present study, sampling restricted to stream segments and substratum types (i.e. excluding riffles and stream reaches) would produce around 75% of all observed families using 17% of the sampling effort employed. This finding indicates that intensive sampling (many riffles and reaches) in few stream segments does not result in efficient assessment of diversity in a region. [source] All creatures great and small: patterns in the stream benthos across a wide range of metazoan body sizeFRESHWATER BIOLOGY, Issue 3 2003Tracey K. Stead SUMMARY 1. The whole metazoan community (i.e. including the meiofauna) of an acidic, fishless stream in south-east England was surveyed over 14 months between March 1999 and April 2000. Invertebrate density, biomass and taxonomic richness were assessed on each sampling occasion in relation to physico-chemical variables. 2. The meiofauna were more numerous and diverse than the macrofauna, while their total biomass occasionally equalled that of the macrofauna. 3. The meiofaunal and macrofaunal assemblages appeared to respond to different environmental factors. The meiofauna showed genuine species turnover through the year, while the macrofauna varied less in taxonomic composition though there were substantial variations in density. 4. These data suggest that the meiofauna and macrofauna exist at different temporal and spatial scales and perceive their environment with a different ,grain'. [source] Does urbanization decrease diversity in ground beetle (Carabidae) assemblages?GLOBAL ECOLOGY, Issue 1 2010Tibor Magura ABSTRACT Aim, We wanted to test whether urbanization has similar effects on biodiversity in different locations, comparing the responses of ground beetle (Coleoptera, Carabidae) assemblages with an urbanization gradient. We also wanted to see if urbanization had a homogenizing effect on ground beetle assemblages. Locations, Nine forested temperate locations in Europe, Canada and Japan. Methods, Published results of the Globenet Project were used. At all locations, three stages were identified: (1) a forested (rural) area, (2) a suburban area where the original forest was fragmented and isolated, and (3) remnants of the original forest in urban parks. These habitats formed an urbanization series. Study arrangements (number and operation of traps) and methods (pitfall trapping) were identical, conforming to the Globenet protocol. Assemblage composition and diversity patterns were evaluated. Diversity relationships were analysed by the Rényi diversity ordering method considering all ground beetles and , separately , the forest specialist species. Taxonomic homogenization was examined by multivariate methods using assemblage similarities. Results, Overall biodiversity (compared by species richness and diversity ordering) showed inconsistent trends by either urbanization intensity or by geographic position. However, when only forest species were compared, diversity was higher in the original rural (forested) areas than in urban forest fragments. Within-country similarities of carabid assemblages were always higher than within-urbanization stage similarities. Main conclusions, Urbanization does not appear to cause a decrease in ground beetle diversity per se. Forest species decline as urbanization intensifies but this trend is masked by an influx of non-forest species. The rural faunas were more similar to the urban ones within the same location than similar urbanization stages were to each other, indicating that urbanization did not homogenize the taxonomic composition of ground beetle faunas across the studied locations. [source] Partitioning phylogenetic and adaptive components of the geographical body-size pattern of New World birdsGLOBAL ECOLOGY, Issue 1 2008Lizabeth Ramirez ABSTRACT Aim To evaluate seasonal body-size patterns for New World birds in geographical space, to develop environmental models to explain the gradients, and to estimate phylogenetic and adaptive contributions. Location The Western Hemisphere. Methods We used range maps to generate gridded geometric mean body masses. Summer and winter patterns were distinguished based on breeding and non-breeding ranges. We first generated the geographical gradients, followed by phylogenetic eigenvector regression to generate body sizes predicted by the birds' positions in a phylogenetic tree, which were used to generate the expected phylogenetic gradient. Subtracting the expected pattern from the observed pattern isolated the adaptive component. Ordinary least squares multiple-regression models examined factors influencing the phylogenetic, adaptive and combined components of the seasonal body-size patterns, and non-spatial and spatial models were compared. Results Birds are larger in the temperate zones than in the tropics. The gradient is quantitatively stronger in winter than in summer. Regression models explained 66.6% of the variance in summer mass and 45.9% of the variance in winter mass. In summer, phylogenetic and adaptive responses of birds contribute equally to the gradient. In winter, the gradient in North America is much stronger than that expected by taxonomic turnover, and responses of species independent of their family membership drive the overall pattern. Main conclusions We confirm Bergmann's rule in New World birds and conclude that winter temperatures ultimately drive the pattern, exerting selection pressures on birds that overwhelm patterns expected by phylogenetic inertia at the family level. However, in summer, the movement of migratory species into the temperate zone weakens the gradient and generates a pattern more congruent with that expected from the taxonomic composition of the fauna. The analytical method we develop here represents a useful tool for partitioning the phylogenetic and non-phylogenetic components of spatially explicit macroecological data. [source] Rapid biodiversity assessment of spiders (Araneae) using semi-quantitative sampling: a case study in a Mediterranean forestINSECT CONSERVATION AND DIVERSITY, Issue 2 2008PEDRO CARDOSO Abstract. 1A thorough inventory of a Mediterranean oak forest spider fauna carried out during 2 weeks is presented. It used a semi-quantitative sampling protocol to collect comparable data in a rigorous, rapid and efficient way. Four hundred and eighty samples of one person-hour of work each were collected, mostly inside a delimited 1-ha plot. 2Sampling yielded 10 808 adult spiders representing 204 species. The number of species present at the site was estimated using five different richness estimators (Chao1, Chao2, Jackknife1, Jackknife2 and Michaelis,Menten). The estimates ranged from 232 to 260. The most reliable estimates were provided by the Chao estimators and the least reliable was obtained with the Michaelis,Menten. However, the behavior of the Michaelis,Menten accumulation curves supports the use of this estimator as a stopping or reliability rule. 3Nineteen per cent of the species were represented by a single specimen (singletons) and 12% by just two specimens (doubletons). The presence of locally rare species in this exhaustive inventory is discussed. 4The effects of day, time of day, collector experience and sampling method on the number of adults, number of species and taxonomic composition of the samples are assessed. Sampling method is the single most important factor influencing the results and all methods generate unique species. Time of day is also important, in such way that each combination of method and time of day may be considered as a different method in itself. There are insignificant differences between the collectors in terms of species and number of adult spiders collected. Despite the high collecting effort, the species richness and abundance of spiders remained constant throughout the sampling period. [source] EFFECT OF CARBONIC ANHYDRASE INHIBITORS ON THE INORGANIC CARBON UPTAKE BY PHYTOPLANKTON NATURAL ASSEMBLAGES,JOURNAL OF PHYCOLOGY, Issue 1 2009Jesús M. Mercado The role of carbonic anhydrase (CA) in inorganic carbon acquisition (dissolved inorganic carbon, DIC) was examined in Alboran Sea phytoplankton assemblages. The study area was characterized by a relatively high variability in nutrient concentration and in abundance and taxonomic composition of phytoplankton. Therefore, the relationship between environmental variability and capacity for using HCO3, via external CA (eCA) was examined. Acetazolamide (AZ, an inhibitor of eCA) inhibited the primary productivity (PP) in 50% of the samples, with inhibition percentages ranging from 13% to 60%. The AZ effect was more prominent in the samples that exhibited PP >1 mg C · m,3 · h,1, indicating that the contribution of eCA to the DIC photosynthetic flux was irrelevant at low PP. The inhibition of primary productivity by AZ was significantly correlated to the abundance of diatoms. However, there was no a relationship between AZ effect and CO2 partial pressure (pCO2) or nutrient concentration, indicating that the variability in the PP percentage supported by eCA was mainly due to differences in taxonomic composition of the phytoplankton assemblages. Ethoxyzolamide (EZ, an inhibitor of both external and internal CA) affected 13 of 14 analyzed samples, with PP inhibition percentages varying from 50% to 95%. The effects of AZ and EZ were partially reversed by doubling DIC concentration. These results imply that CA activity (external and/or internal) was involved in inorganic carbon acquisition in most the samples. However, EZ effect was not correlated with pCO2 or taxonomic composition of the phytoplankton. [source] Taphonomy and compositional fidelity of Quaternary fossil assemblages of terrestrial gastropods from carbonate-rich environments of the Canary IslandsLETHAIA, Issue 3 2008YURENA YANES Quaternary aeolian deposits of the Canary Islands contain well-preserved terrestrial gastropods, providing a suitable setting for assessing the taphonomy and compositional fidelity of their fossil record over ~13 kyr. Nine beds (12, 513 shells) have been analysed in terms of multivariate taphonomic and palaeoecological variables, taxonomic composition, and the stratigraphic and palaeontological context. Shells are affected by carbonate coatings, colour loss and fragmentation. Shell preservation is size-specific: juveniles are less fragmented and show colour preservation more commonly than adults. In palaeosols, the adult shell density correlates negatively with the proportion of fragmented adults, negatively with the proportion of juveniles, and positively with the proportion of adults with coatings. High bioturbation intensity in palaeosols is associated with low shell fragmentation and high proportion of shells with coatings. These relationships imply that high adult density in palaeosols was driven by an increase in shell production rate (related to a decrease in predation rates on adults and a decrease in juvenile mortality) and a decrease in shell destruction rate (related to an increase in durability enhanced by carbonate precipitation). In dunes, the relationships between taphonomic alteration, shell density and bioturbation are insignificant. However, dune assemblages are characterized by a lower frequency of shells with coatings and higher rates of colour loss, indicating lower shell durability in dunes than in palaeosols. Additionally, non-random differences in the coating proportion among palaeosols imply substantial temporal variation in the rate of carbonate crust formation, reflecting long-term changes in bioturbation intensity that covaries positively with shell preservation. Dunes and palaeosols do not differ in species abundances despite differences in the degree of shell alteration, suggesting that both weakly and strongly altered assemblages offer data with a high compositional fidelity. Carbonate-rich terrestrial deposits originating in arid conditions can enhance the preservation of gastropods and result in fossil assemblages that are suitable for palaeoecological and palaeoenvironmental studies of terrestrial ecosystems. [source] A unified mathematical framework for the measurement of richness and evenness within and among multiple communitiesOIKOS, Issue 2 2004Thomas D. Olszewski Biodiversity can be divided into two aspects: richness (the number of species or other taxa in a community or sample) and evenness (a measure of the distribution of relative abundances of different taxa in a community or sample). Sample richness is typically evaluated using rarefaction, which normalizes for sample size. Evenness is typically summarized in a single value. It is shown here that Hurlbert's probability of interspecific encounter (,1), a commonly used sample-size independent measure of evenness, equals the slope of the steepest part of the rising limb of a rarefaction curve. This means that rarefaction curves provide information on both aspects of diversity. In addition, regional diversity (gamma) can be broken down into the diversity within local communities (alpha) and differences in taxonomic composition among local communities (beta). Beta richness is expressed by the difference between the composite rarefaction curve of all samples in a region with the collector's curve for the same samples. The differences of the initial slopes of these two curves reflect the beta evenness thanks to the relationship between rarefaction and ,1. This relationship can be further extended to help interpret species-area curves (SAC's). As previous authors have described, rarefaction provides the null hypothesis of passive sampling for SAC's, which can be interpreted as regional collector's curves. This allows evaluation of richness and evenness at local and regional scales using a single family of well-established, mathematically related techniques. [source] Rare species in communities of tropical insect herbivores: pondering the mystery of singletonsOIKOS, Issue 3 2000Vojtech Novotný The host specificity, taxonomic composition and feeding guild of rare species were studied in communities of herbivorous insects in New Guinea. Leaf-chewing and sap-sucking insects (Orthoptera, Phasmatodea, Coleoptera, Lepidoptera and Hemiptera-Auchenorrhyncha) were sampled from 30 species of trees and shrubs (15 spp. of Ficus, Moraceae, six spp. of Macaranga and nine species of other Euphorbiaceae) in a lowland rain forest. Feeding trials were performed with all leaf-chewers in order to exclude transient species. Overall, the sampling produced 80,062 individuals of 1050 species. The species accumulation curve did not attain an asymptote, despite 950 person-days of sampling. Rare species, defined as those found as single individuals, remained numerous even in large samples and after the exclusion of transient, non-feeding species. There was no difference among plant species in the proportion of rare species in their herbivore communities, which was, on average, 45%. Likewise, various herbivore guilds and taxa had all very similar proportions of rare and common species. There was also no difference between rare and common species in their host specificity. Both highly specialised species and generalists, feeding on numerous plants, contributed to the singleton records on particular plant species. Predominantly, a species was rare on a particular host whilst more common on other, often related, host species, or relatively rare on numerous other host plants, so that its aggregate population was high. Both cases are an example of the "mass effect", since it is probable that such rare species were dependent on a constant influx of immigrants from the other host plants. These other plants were found particularly often among congeneric plants, less so among confamilial plants from different genera and least frequently among plants from different families. There were also 278 very rare species, found as one individual on a single plant species only. Their host specificity could not be assessed; they might have been either very rare specialists, or species feeding also on other plants, those that were not studied. The former possibility is unlikely since monophagous species, collected as singletons at the present sampling effort, would have existed at an extremely low population density, less than 1 individual per 10 ha of the forest. [source] Variability of UVR Effects on Photosynthesis of Summer Phytoplankton Assemblages from a Tropical Coastal Area of the South China Sea,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2007Kunshan Gao From June to September 2005, we carried out experiments to determine the ultraviolet radiation (UVR) -induced photoinhibition of summer phytoplankton assemblages from a coastal site of the South China Sea. Variability in taxonomic composition was determined throughout the summer, with a peak chlorophyll a (chl a,20 ,g chl a L,1) dominated by the diatom Skeletonema costatum that was detected early in the study period; the rest of the time samples were characterized by monads and flagellates, with low chl a values (1,5 chl a ,g L,1). Surface water samples were placed in quartz tubes, inoculated with radiocarbon and exposed to solar radiation for 2,3 h to determine photosynthetic rates under three quality radiation treatments (i.e. PAB, 280,700 nm; PA, 320,700 nm and P, 400,700 nm) using different filters and under seven levels of ambient irradiance using neutral density screens (PvsE curves). UVR inhibition of samples exposed to maximum irradiance (i.e. at the surface) varied from ,12.2% to 50%, while the daytime-integrated UVR-related photoinhibition in surface seawater varied from ,62% to 7%. The effects of UVR on the photosynthetic parameters PBmax and Ek were also variable, but UV-B accounted for most of the observed variability. During sunny days, photosynthesis of microplankton (>20 ,m) and piconanoplankton (<20 ,m) were significantly inhibited by UVR (mostly by UV-B). However, during cloudy days, while piconanoplankton cells were still inhibited by UVR, microplankton cells used UVR (mostly UV-A) as the source of energy for photosynthesis, resulting in higher carbon fixation in samples exposed to UVR than the ones exposed only to photosynthetically active radiation (PAR). Our results indicate that size structure and cloudiness clearly condition the overall impact of UVR on phytoplankton photosynthesis in this tropical site of South China. In addition, model predictions for this area considering only PAR for primary production might have underestimated carbon fixation due to UVR contribution. [source] Impact of Solar Ultraviolet Radiation on Marine Phytoplankton of Patagonia, Argentina,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2005E. Walter Helbling ABSTRACT Patagonia area is located in close proximity to the Antarctic ozone "hole" and thus receives enhanced ultraviolet B (UV-B) radiation (280,315 nm) in addition to the normal levels of ultraviolet A (UV-A; 315,400 nm) and photosynthetically available radiation (PAR; 400-700 nm). In marine ecosystems of Patagonia, normal ultraviolet radiation (UVR) levels affect phytoplankton assemblages during the three phases of the annual succession: (1) prebloom season (late summer-fall), (2) bloom season (winter-early spring) and (3) postbloom season (late spring-summer). Small-size cells characterize the pre-and postbloom communities, which have a relatively high photosynthetic inhibition because of high UVR levels during those seasons. During the bloom, characterized by micro-plankton diatoms, photosynthetic inhibition is low because of the low UVR levels reaching the earth's surface during winter; this community, however, is more sensitive to UV-B when inhibition is normalized by irradiance (i.e. biological weighting functions). In situ studies have shown that UVR significantly affects not only photosynthesis but also the DNA molecule, but these negative effects are rapidly reduced in the water column because of the differential attenuation of solar radiation. UVR also affects photosynthesis versus irradiance (P vs E) parameters of some natural phytoplankton assemblages (i.e. during the pre- but not during the postbloom season). However, there is a significant temporal variability of P vs E parameters, which are influenced by the nutrient status of cells and taxonomic composition; taxonomic composition is in turn associated with the stratification conditions (e.g. wind speed and duration). In Patagonia, wind speed is one of the most important variables that conditions the development of the winter bloom by regulating the depth of the upper mixed layer (UML) and hence the mean irradiance received by cells. Studies on the interactive effects of UVR and mixing show that responses of phytoplankton vary according to the taxonomic composition and cell structure of assemblages; therefore cells use UVR if >90% of the euphotic zone is being mixed. In fact, cell size plays a very important role when estimating the impact of UVR on phytoplankton, with large cells being more sensitive when determining photosynthesis inhibition, whereas small cells are more sensitive to DNA damage. Finally, in long-term experiments, it was determined that UVR can shape the diatom community structure in some assemblages of coastal waters, but it is virtually unknown how these changes affect the trophody-namics of marine systems. Future studies should consider the combined effects of UVR on both phytoplankton and grazers to establish potential changes in biodiversity of the area. [source] Beyond Gorilla and Pongo: Alternative models for evaluating variation and sexual dimorphism in fossil hominoid samplesAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2009Jeremiah E. Scott Abstract Sexual size dimorphism in the postcanine dentition of the late Miocene hominoid Lufengpithecus lufengensis exceeds that in Pongo pygmaeus, demonstrating that the maximum degree of molar size dimorphism in apes is not represented among the extant Hominoidea. It has not been established, however, that the molars of Pongo are more dimorphic than those of any other living primate. In this study, we used resampling-based methods to compare molar dimorphism in Gorilla, Pongo, and Lufengpithecus to that in the papionin Mandrillus leucophaeus to test two hypotheses: (1) Pongo possesses the most size-dimorphic molars among living primates and (2) molar size dimorphism in Lufengpithecus is greater than that in the most dimorphic living primates. Our results show that M. leucophaeus exceeds great apes in its overall level of dimorphism and that L. lufengensis is more dimorphic than the extant species. Using these samples, we also evaluated molar dimorphism and taxonomic composition in two other Miocene ape samples,Ouranopithecus macedoniensis from Greece, specimens of which can be sexed based on associated canines and P3s, and the Sivapithecus sample from Haritalyangar, India. Ouranopithecus is more dimorphic than the extant taxa but is similar to Lufengpithecus, demonstrating that the level of molar dimorphism required for the Greek fossil sample under the single-species taxonomy is not unprecedented when the comparative framework is expanded to include extinct primates. In contrast, the Haritalyangar Sivapithecus sample, if itrepresents a single species, exhibits substantially greater molar dimorphism than does Lufengpithecus. Given these results, the taxonomic status of this sample remains equivocal. Am J Phys Anthropol, 2009. © 2009 Wiley-Liss, Inc. [source] A Marquesan coral reef (French Polynesia) in historical context: an integrated socio-ecological approachAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 6 2009Shankar Aswani Abstract 1.Marine biologists are increasingly aware of the impact that even small human populations can have on coral reefs around the world, while conservationists and fisheries managers have a growing appreciation of the importance of culturally informed management strategies in coral reef conservation efforts. Despite these recognitions, however, examples of integrated field studies are limited. 2.In this paper evidence from various disciplines is used to study the interaction between humans and one of the largest reefs in the Marquesas Islands, at Anaho Bay, Nuku Hiva Island, with the aim of assessing possible anthropogenic impacts over time. 3.First, it reports on a marine biological survey of the benthic substrates of the bay and the taxonomic composition and spatial distributions of the local fish species. Second, it draws on results from an ongoing archaeological study and integrates these with interviews of village elders to gain a historical perspective on the reef and potential human impacts. 4.The biological results indicated that the reef is in a state of decline, although fish densities are moderately high. The archaeological evidence, in turn, demonstrates that human populations have occupied this valley for at least the last 700 years. Throughout this period marine resources have been an important source of both food and raw materials for tools. The archaeological study also highlights aspects of landscape change, both natural and human-induced, that probably have been detrimental to reef health. 5.Using the combined biological and anthropological data, this paper considers the nexus of factors that have led to the current reef conditions and considers management issues for the future. Key in this regard are processes that have initiated erosion and soil run-off, and fluctuations in the local human populations. Copyright © 2008 John Wiley & Sons, Ltd. [source] Space,time patterns of co-variation of biodiversity and primary production in phytoplankton guilds of coastal marine environmentsAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 6 2003Maria Rosaria Vadrucci Abstract 1.The relevance of biodiversity to ecosystem processes is a major topic in ecology. Here, we analyse the relationship between biodiversity and productivity of the nano- and micro-phytoplankton guilds in coastal marine ecosystems. 2.The patterns of variation of species richness, diversity and primary productivity (as 14C assimilation) were studied in two marine areas: a eutrophic,mesotrophic area beside the River Po delta (northern Adriatic) and an oligotrophic area around the Salento peninsula (southern Adriatic,Ionian). The study was carried out at 23 sites in the northern area and at 45 sites in the southern area. Sites were arranged on expected spatial and temporal gradients of primary productivity variation, according to distance from the coast, optical depths and seasonal period. 3.167 taxa were identified in the northern area and 153 taxa in the southern area. In both areas, the taxonomic composition of the nano- and micro-phytoplankton guilds exhibited greater temporal than spatial variation. The latter was much higher in the southern area than in the northern area (average dissimilarity between stations being 70.7±0.8% and 44.7±4.2% respectively). 4.Primary productivity varied in space and time on the gradients considered. Phytoplankton species richness and diversity exhibited significant patterns of variation in space and time; overall, these were inversely related to the primary productivity patterns in the northern area, whereas they were directly related in the southern area. 5.The small individual size and the high turnover rate of phytoplankton are likely to underlie the observed relationships, which emphasized a threshold response to nutrient enrichment in agreement with the ,paradox of enrichment'. Under resource enrichment conditions, the high turnover of producers leads to hierarchical partitioning of the available resources with an increasing dominance of a few species. Therefore, the relationship observed here seems likely to be explained by the complementarity hypothesis. Copyright © 2003 John Wiley & Sons, Ltd. [source] Impacts of the invasive Argentine ant on native ants and other invertebrates in coastal scrub in south-eastern AustraliaAUSTRAL ECOLOGY, Issue 3 2009ALEXEI D. ROWLES Abstract Invasive ants threaten native biodiversity and ecosystem function worldwide. Although their principal direct impact is usually the displacement of native ants, they may also affect other invertebrates. The Argentine ant, Linepithema humile (Dolichoderinae), one of the most widespread invasive ant species, has invaded native habitat where it abuts peri-urban development in coastal Victoria in south-eastern Australia. Here we infer impacts of the Argentine ant on native ants and other litter and ground-dwelling invertebrates by comparing their abundance and taxonomic composition in coastal scrub forest either invaded or uninvaded by the Argentine ant. Species composition of native ants at bait stations and extracted from litter differed significantly between Argentine ant-invaded and uninvaded sites and this was consistent across years. Argentine ants had a strong effect on epigeic ants, which were either displaced or reduced in abundance. The native ant Rhytidoponera victoriae (Ponerinae), numerically dominant at uninvaded sites, was completely absent from sites invaded by the Argentine ant. However, small hypogeic ants, including Solenopsis sp. (Myrmicinae) and Heteroponera imbellis (Heteroponerinae), were little affected. Linepithema humile had no detectable effect upon the abundance and richness of other litter invertebrates. However, invertebrate group composition differed significantly between invaded and uninvaded sites, owing to the varied response of several influential groups (e.g. Collembola and Acarina). Floristics, habitat structure and measured environmental factors did not differ significantly between sites either invaded or uninvaded by Argentine ants, supporting the contention that differences in native ant abundance and species composition are related to invasion. Changes in the native ant community wrought by Argentine ant invasion have important implications for invertebrate communities in southern Australia and may affect key processes, including seed dispersal. [source] Can Functional Traits Predict Ecological Interactions?BIOTROPICA, Issue 3 2010A Case Study Using Rain forest Frugivores, Plants in Australia ABSTRACT In rain forest, the large numbers of species of fleshy-fruited plants and frugivorous animals result in a large number of potential fruit,frugivore interactions, which are challenging to survey in the field. Yet, knowledge of these relationships is needed to predict consequences of changes in the frugivore assemblage for seed dispersal. In the absence of comprehensive dietary information, it may be possible to delineate between frugivores that disperse different plants using ,functional traits,' or morphological and behavioral attributes of frugivores that interact with differences in salient characteristics of plant species. Here we use data on the consumption of 244 Australian rain forest plant species by 38 bird species to test for associations between patterns of frugivory and birds': (1) degree of frugivory, (2) gape width, and (3) seed treatment (seed crushing or seed dispersing). Degree of frugivory and gape width explain 74 percent of the variation in the sizes of fruits consumed by frugivorous birds. Among birds that consume a substantial dietary proportion of fruit, birds with wider gapes consume larger fruits. In contrast, this relationship was not shown by birds for which fruit is only a minor dietary component. Degree of frugivory and gape width, together with seed treatment, also strongly predict the overall taxonomic composition and diversity of plants consumed by bird species. Functional classifications of frugivore species may prove useful in developing a predictive understanding of fruit,frugivore interactions in other rain forest regions where detailed dietary information is not available for most frugivores. [source] | |||||||||||||||||||||||||