EDUCATIONAL THEORY, Issue 4 2008
Maarten Simons
Doubting whether these concepts and related historical-analytical perspectives are still useful, the authors suggest the concept "learning apparatus" as a point of departure for an analysis of the "grammar of learning." They draw on Michel Foucault's analysis of governmentality to describe how learning has become a matter of both government and self-government. In describing the governmentalization of learning and the current assemblage of a "learning apparatus," Simons and Masschelein indicate how the concept of learning has become disconnected from education and teaching and has instead come to refer to a kind of capital, to something for which the learner is personally responsible, to something that can and should be managed, and to something that must be employable. Finally, the authors elaborate how these discourses combine to play a crucial role in contemporary advanced liberalism that seeks to promote entrepreneurship. [source]

IMPACT OF THE INVASIVE SEAWEED SARGASSUM MUTICUM (PHAEOPHYTA) ON AN INTERTIDAL MACROALGAL ASSEMBLAGE,

JOURNAL OF PHYCOLOGY, Issue 5 2005
Íñigo Sánchez
The impact of the invasive seaweed Sargassum muticum (Yendo) Fensholt on a low intertidal macroalgal assemblage was assessed at a semiexposed rocky shore in northern Spain between 2002 and 2004. Sargassum muticum plants were removed from the mature macroalgal assemblage and from those occurring along the successional process of the assemblage. Biomass, richness, diversity, and percentage cover of macroalgae in experimental plots were compared with unmanipulated controls. The effect of S. muticum removal on the macroalgal assemblage more than 2 years after the beginning of the experiment was negligible. Moreover, no differences between treatments were detected in the general patterns of succession. Only significant differences in S. muticum abundance were detected between treatments at the end of the experiment. We suggest that the low abundance of S. muticum at this intertidal level and its pseudoperennial life cycle may limit competition with native macroalgae. However, long-term removal experiments may be a more indicator of the impact of S. muticum at the upper limit of its vertical distribution. [source]

A NEW ELASMOBRANCH ASSEMBLAGE FROM THE LOWER CRETACEOUS OF THAILAND

PALAEONTOLOGY, Issue 3 2006
HENRI CAPPETTA
Abstract:, The discovery of a new elasmobranch assemblage from the Lower Cretaceous of Thailand allows expansion of the faunal list and refinement of our knowledge of the dental morphological features of some previously described taxa. The root morphology of Thaiodus is now known and a more complete description of the dentition of the genus Heteroptychodus, known formerly by a single tooth from Japan, is given. A new genus and species, Acrorhizodus khoratensis, characterized by teeth of very special morphology is described. Besides these taxa, some teeth of a genus probably close to Hybodus, but with more bulbous teeth, are present. Owing to the sedimentological characters of the deposits and the associated fauna (dinosaurs), it is probable that this elasmobranch fauna lived in a freshwater or brackish environment. The simultaneous occurrence of teeth of Heteroptychodus in Thailand and Japan favours the existence of a large continental area in south-east Asia during the Early Cretaceous. [source]

EFFECT OF CARBONIC ANHYDRASE INHIBITORS ON THE INORGANIC CARBON UPTAKE BY PHYTOPLANKTON NATURAL ASSEMBLAGES,

JOURNAL OF PHYCOLOGY, Issue 1 2009
Jesús 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]

From Assemblage to Community

CONSERVATION BIOLOGY, Issue 5 2001
Reed Noss Past President
No abstract is available for this article. [source]

The ammonoids from the Dalle à Merocanites of Timimoun (Late Tournaisian,Early Viséan; Gourara, Algeria)

FOSSIL RECORD-MITTEILUNGEN AUS DEM MUSEUM FUER NATURKUNDE, Issue 1 2010
Volker Ebbighausen
Abstract The ammonoids from the Early Carboniferous (Mississippian) Dalle à Merocanites of Timimoun (Gourara, Algeria) are described. The following new ammonoid taxa are introduced: subfamily Hammatocyclinae n. subfam., Hammatocyclus pollex n. sp., Hammatocyclus corrugatus n. sp., Neopericyclus arenosus n. sp., Ammonellipsites pareyni n. sp., Ammonellipsites menchikoffi n. sp., Ammonellipsites conradae n. sp., Muensteroceras fabrei n. sp., Eurites commutatus n. sp., Eurites pondus n. sp., subfamily Trimorphoceratinae n. subfam., Trimorphoceras n. gen., Trimorphoceras crassilens n. sp., Trimorphoceras absolutum n. sp., Trimorphoceras molestum n. sp., Obturgites n. gen., Obturgites polysarcus n. sp., Obturgites oligosarcus n. sp., Dzhaprakoceras dzhazairense n. sp., and Merocanites merocanites n. sp. These species occur in one very prolific horizon and can be attributed to the North African Ammonellipsites - Merocanites Assemblage (Fascipericyclus - Ammonellipsites Genus Zone; Late Tournaisian to Early Viséan). They represent one of the most diverse ammonoid faunas known from this time interval. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Ammonoids from the Dalle des Iridet of the Mouydir and Ahnet (Central Sahara) and the Formation d'Hassi Sguilma of the Saoura Valley (Late Tournaisian,Early Viséan; Algeria)

FOSSIL RECORD-MITTEILUNGEN AUS DEM MUSEUM FUER NATURKUNDE, Issue 1 2010
Dieter Korn
Abstract Four ammonoid species are described from the Early Carboniferous (Mississippian) Iridet Formation of the Ahnet and Mouydir (Central Sahara, Algeria); three of which are new: Eurites temertassetensis n. sp., Trimorphoceras teguentourense n. sp., and Trimorphoceras azzelmattiense n. sp. The species can be attributed to the North African Ammonellipsites - Merocanites Assemblage (Fascipericyclus - Ammonellipsites Genus Zone; Late Tournaisian to Early Viséan). Additionally, the two new species Ammonellipsites sguilmensis n. sp. and Muensteroceras beniabbesense n. sp. are described from the time equivalent Hassi Sguilma Formation of the Saoura Valley (north-western Algeria). (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Note on a Highly Diverse Rotifer Assemblage (Rotifera: Monogononta) in a Laotian Rice Paddy and Adjacent Pond

INTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 6 2007
Hendrik Segers
Abstract During August 1999, the authors conducted a sampling campaign in the PDR Laos, in order to contribute to the chorology of rotifers in the region. Two samples, collected from a rice paddy and an adjacent pond near Vientiane, Laos, contained a total of 135 rotifer species including several that appear new to science or that warrant taxonomical or biogeographical comments. No new species can be named, but Cephalodella boettgeri Koste and Floscularia armataSegers are recorded for the second time ever after their description from South America, and Parencentrum lutetiae (Harring and Myers) and Polyarthra luminosaKutikova are new to Southeast Asia. This raises the number of rotifers recorded from Laos from 9 to 130. The diversity recorded is remarkable, especially when compared with that of similar habitats in the Thai part of the floodplain of River Mekong and its tributaries. Different agricultural practices may account for the difference in species richness. Similar highly diverse rotifer faunas are known to occur in natural, tropical and subtropical floodplain systems only. This accords with the view that rice paddies can be regarded as artificial wetlands or floodplain systems, which, if managed taking biodiversity concerns into account, may have a potential for the conservation of freshwater biodiversity. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Rodent assemblage in a habitat mosaic within the Valley Thicket vegetation of the Eastern Cape Province, South Africa

AFRICAN JOURNAL OF ECOLOGY, Issue 1 2008
Boris Kry, tufek
Abstract We sampled small mammal assemblage in a mosaic of Valley Thicket vegetation in the Great Fish River Reserve during the summers of 2001 and 2002. Assemblage was dominated by seven rodent species with a single nonrodent species (Elephantulus edwardii) in the 357 trapped specimens. Rhabdomys dilectus was the most abundant in both years, followed by Mus minutoides (ranking 2nd in 2001) and Mastomys coucha (2nd in 2002). These three species, which are widespread generalists, made up 85.0% of the total rodent catch in 2001 and 74.3% in 2002. Individual species were captured on 2,14 sites of a total of 17 and M. minutoides was the most widespread. The majority of samples consisted of two (ten sites in a pooled sample for 2 years) or three species (ten sites). Significant morphological structuring was found only in two-species samples. Species turnover was high both among sites and between the 2 years. We found no evidence of significant nested structure which would suggest hierarchical sets of ecological relationships among the species. Vegetation structure explained better than species interactions, the population variables in the rodent assemblage. Résumé Nous avons échantillonné l'assemblage de petits mammifères dans une mosaïque végétale de Valley Thicket dans la Great Fish River Reserve au cours des étés de 2001 et 2002. L'assemblage des 357 spécimens attrapés était dominé par sept espèces de rongeurs et une autre espèce (Elephantulus edwardii). Rhabdomys dilectusétait l'espèce la plus abondante les deux années, suivie par Mus minutoides (classé 2ème en 2001) et par Mastomys coucha (2ème en 2002). Ces trois espèces, qui sont des espèces généralistes très répandues, représentaient 85,0% des prises totales de rongeurs en 2001 et 74,3% en 2002. Les espèces individuelles furent capturées sur deux à 14 sites sur un total de 17, et Mus minutoidesétait la plus répandue. La majorité des échantillons se composaient de deux (10 sites sur un échantillonnage groupé de deux ans) ou trois espèces (dix sites). On n'a découvert de structure morphologique significative que dans des échantillons de deux espèces. Le turnover des espèces était élevé entre les différents sites et entre les années. Nous n'avons trouvé aucune preuve d'une structure significative qui puisse suggérer l'existence de relations hiérarchiques écologiques entre les espèces. La structure de la végétation expliquait mieux que les interactions interspécifiques les variables des populations de l'assemblage des rongeurs. [source]

Surviving the end-Ordovician extinctions: evidence from the earliest Silurian brachiopods of northeastern Jiangxi and western Zhejiang provinces, East China

LETHAIA, Issue 1 2006
JIA-YU RONG
Earliest Rhuddanian (Silurian) brachiopods are recorded from the basal part of the Lower Llandovery Shiyang and Anji formations in western Zhejiang and northeastern Jiangxi provinces, East China. Associated graptolites including Normalograptus jerini indicate the lowest Rhuddanian Akidograptus ascensus Biozone. The surviving brachiopod fauna includes 19 genera dominated by orthids and strophomenids, whereas pentamerids and atrypids that inhabited mainly warmer water regimes, and were almost absent in the cool/cold Hirnantia Fauna, occur rarely in the studied fauna. Each family is represented by a single genus that seeded their recovery. The predominance of these long-ranging and widely distributed genera is one of major characters of the brachiopod survival in east China. From qualitative and quantitative analysis of faunal composition, diversity and abundance, with evidences from palaeoecology and palaeogeography, the Levenea qianbeiensis Association, Katastrophomena-Leptaena-Levenea Association, and Glyptorthis-Epitomyonia-Levenea Association are recognized and assigned to BA (Benthic Assemblage) 2, BA3, and an ecozone close to the BA3-4 boundary respectively. No Lazarus genera are recorded in this study. Skenidioides and Epitomyonia were chiefly regarded as deeper-water taxa in the Ordovician and Silurian, but are recorded from shallow-water in east China during the early Rhuddanian, indicating an ecologic experiment with these taxa migrating from deep into shallower, better-oxygenated sites at the crisis time and during the subsequent survival interval. This study further demonstrates that the brachiopod faunal turnover after the end-Ordovician extinctions may not have been completed until the late Rhuddanian in South China. [source]

Sulfur Isotope Study and Re-examination of Ore Mineral Assemblage of the Hol Kol and the Tul Mi Chung Skarn-type Copper,Gold Deposits of the Suan Mining District, Korean Peninsula

RESOURCE GEOLOGY, Issue 4 2000
Akira Imai
Abstract: Ore specimens collected by the late Professor Takeo Watanabe from the Hol Kol and the Tul Mi Chung deposits, Suan mining district, Korean peninsula, were examined. In addition, measurements of sulfur isotopic ratio of ores and preliminary fluid inclusion microthermometry were carried out. Ores from the New orebody of the Hol Kol deposit consist mainly of bornite, wittichenite and chalcopyrite presently, which exhibit lamellae intergrowth texture, associated with native bismuth and electrum. Bismuthian bornite solid solution is considered to be a principal initial phases, while native bismuth was nucleated as molten bismuth melt initially. The occurrence of cubanite, miharaite, carrollite, siegenite, hessite and geikielite are recognized from the New orebody. Ores from the Eastern orebody of the Hol Kol deposit consist chiefly of chalcopyrite, occasionally associated with trace amounts of pyrrhotite, pyrite, bismuthinite and rare tellurobismuthite, while an ore specimen from the Western orebody consists mainly of sphalerite associated with chalcopyrite, pyrite and galena. Ores from the Tul Mi Chung deposit consist mainly of chalcopyrite and pyrite, occasionally associated with magnetite, sphalerite, galena and rare molybdenite. Some portions of magnetite are revealed to be silician magnetite. Sulfur fugacity is supposed to be below the stability field of bismuthinite in the New orebody. A reducing condition is suggested by the occurrence of geikielite without Fe3+ content. The sulfur and oxygen fugacities for the Eastern and Western orebodies of the Hol Kol deposit and for the Tul Mi Chung deposit were higher than the New orebody of the Hol Kol deposit. On the other hand, the Suan granite (porphyritic granodiorite) and the Chil Sing Dai granite (biotite granite porphyry) from the Hol Kol area can be classified as weakly magnetic magnetite-series. Polyphase fluid inclusions are observed in gangue diopside associated with Cu ore of two specimens. The dissolution temperatures of daughter crystals are 394±26°C and 442±45°C, while the disappearing temperatures of vapor bubble were 475±25°C and > 500°C. Highly saline fluids were responsible for the mineralization at the Hol Kol deposit. The ,34S values of ore sulfides of the Hol Kol and the Tul Mi Chung deposit range from +11. 5% to +16. 1%, having anomalous lower values mainly from the Tul Mi Chung deposit. Such anomalous lower 634S values can be caused by isotopic fractionation against oxidized sulfur species. The ,34S value of bulk sulfur in the ore solutions responsible for the Hol Kol and the Tul Mi Chung deposit is estimated to be +13.5±2.5,. [source]

Bird Assemblage and Visitation Pattern at Fruiting Elmerrillia tsiampaca (Magnoliaceae) Trees in Papua New Guinea

BIOTROPICA, Issue 2 2010
Steffen Oppel
ABSTRACT Most tropical trees produce fleshy fruits that attract frugivores that disperse their seeds. Early demography and distribution for these tree species depend on the effects of frugivores and their behavior. Anthropogenic changes that affect frugivore communities could ultimately result in changes in tree distribution and population demography. We studied the frugivore assemblage at 38 fruiting Elmerrillia tsiampaca, a rain forest canopy tree species in Papua New Guinea. Elmerrillia tsiampaca is an important resource for frugivorous birds at our study site because it produces abundant lipid-rich fruits at a time of low fruit availability. We classified avian frugivores into functional disperser groups and quantified visitation rates and behavior at trees during 56 canopy and 35 ground observation periods. We tested predictions derived from other studies of plant,frugivore interactions with this little-studied frugivore assemblage in an undisturbed rain forest. Elmerrillia tsiampaca fruits were consumed by 26 bird species, but most seeds were removed by eight species. The most important visitors (Columbidae, Paradisaeidae and Rhyticeros plicatus) were of a larger size than predicted based on diaspore size. Columbidae efficiently exploited the structurally protected fruit, which was inconsistent with other studies in New Guinea where structurally protected fruits were predominantly consumed by Paradisaeidae. Birds vulnerable to predation foraged for short time periods, consistent with the hypothesis that predator avoidance enhances seed dispersal. We identified seven functional disperser groups, indicating there is little redundancy in disperser groups among the regular and frequent visitors to this tropical rain forest tree species. [source]

Novel Iodinated Diterpenes from a Marine Cyanobacterium and Red Alga Assemblage.

CHEMINFORM, Issue 9 2004
Philip G. Williams
Abstract For Abstract see ChemInform Abstract in Full Text. [source]

Effects of Conversion of Dry Tropical Forest to Agricultural Mosaic on Herpetofaunal Assemblages

CONSERVATION BIOLOGY, Issue 2 2008
IRERI SUAZO-ORTUÑO
atributos de vulnerabilidad; bosque tropical seco; ensambles herpetofaunísticos; modificación del hábitat; mosaico agrícola Abstract:,We explored the impact of forest conversion to agricultural mosaic on anuran, lizard, snake, and turtle assemblages of Neotropical dry forests. Over 2 years, we sampled 6 small watersheds on the west coast of Mexico, 3 conserved and 3 disturbed. The disturbed watersheds were characterized by a mosaic of pastures and cultivated fields (corn, beans, squash) intermingled with patches of different successional stages of dry forest. In each watershed, we conducted 11 diurnal and nocturnal time-constrained searches in 10 randomly established plots. We considered vulnerability traits of species in relation to habitat modification. Eighteen anuran, 18 lizard, 23 snake, and 3 turtle species were recorded. Thirty-six species (58%) occurred in both forest conditions, and 14 (22%) and 12 species (19%) occurred only in the conserved and disturbed sites, respectively. Assemblages responded differently to disturbance. Species richness, diversity, and abundance of lizards were higher in disturbed forests. Anuran diversity and species richness were lower in disturbed forest but abundance was similar in both forest conditions. Diversity, richness, and abundance of turtles were lower in disturbed forest. The structure and composition of snake assemblages did not differ between forest conditions. We considered species disturbance sensitive if their abundance was significantly less in disturbed areas. Four anuran (22%), 2 lizard (11%), and 3 turtle (100%) species were sensitive to disturbance. No snake species was sensitive. The decline in abundance of disturbance-sensitive species was associated with the reduction of forest canopy cover, woody stem cover, roots, and litter-layer ground cover. Anuran species with small body size and direct embryonic development were especially sensitive to forest disturbance. An important goal for the conservation of herpetofauna should be the determination of species traits associated with extinction or persistence in agricultural mosaics. Resumen:,Exploramos el impacto de la conversión de bosques a mosaico agrícola sobre ensambles de lagartijas, serpientes y tortugas de bosques Neotropicales secos. Durante 2 años muestreamos 6 cuencas pequeñas, 3 conservadas y 3 perturbadas, en la costa occidental de México. Las cuencas perturbadas se caracterizaron por un mosaico de pastizales y campos cultivados (maíz, frijol, calabaza) entremezclados con parches de bosque seco en diferentes etapas sucesionales. En cada cuenca, realizamos 11 búsquedas diurnas y nocturnas en 10 parcelas establecidas aleatoriamente. Consideramos los atributos de vulnerabilidad de especies en relación con la modificación del hábitat. Registramos 18 especies de lagartijas, 23 de serpientes y 3 de tortugas. Treinta y seis especies (58%) ocurrieron en ambas condiciones de bosque, y 14 (22%) y 12 (19%) especies solo ocurrieron en los sitios conservados y perturbados, respectivamente. Los ensambles respondieron a la perturbación de manera diferente. La riqueza de especies, la diversidad y la abundancia de lagartijas fueron mayores en los bosques perturbados. La diversidad y riqueza de especies de anuros fueron menores en el bosque perturbado pero la abundancia fue similar en ambas condiciones de bosque. La diversidad, riqueza de especies y abundancia de tortugas fueron menores en el bosque perturbado. La estructura y la composición de los ensambles de serpientes no difirieron entre condiciones de bosque. Consideramos que las especies eran sensibles a la perturbación si su abundancia fue significativamente menor en las áreas perturbadas. Cuatro (22%) especies de anuros, 2 (11%) de lagartijas y 3 (100%) de tortugas fueron sensibles a la perturbación. Ninguna especie de serpiente fue sensible. La declinación en la abundancia de especies sensibles a la perturbación se asoció con la reducción en la cobertura del dosel, de tallos leñosos, raíces y hojarasca. Las especies de anuros de cuerpo pequeño y desarrollo embrionario directo fueron especialmente sensibles a la perturbación del bosque. La determinación de atributos de las especies asociadas con su extinción o persistencia en mosaicos agrícolas debería ser una meta importante para la conservación de la herpetofauna. [source]

Smaller and more numerous harvesting gaps emulate natural forest disturbances: a biodiversity test case using rove beetles (Coleoptera, Staphylinidae)

DIVERSITY AND DISTRIBUTIONS, Issue 6 2008
Jan Klimaszewski
ABSTRACT Aim To evaluate changes in the abundance, species richness and community composition of rove beetles (Coleoptera, Staphylinidae) in response to three configurations of experimental gap cuts and to the effects of ground scarification in early succession yellow birch-dominated boreal forest. In each experimental treatment, total forest removed was held constant (35% removal by partial cutting with a concomitant decrease in gap size) but the total number of gaps was increased (two, four and eight gaps, respectively), resulting in an experimental increase in the total amount of ,edge' within each stand. Location Early succession yellow birch-dominated forests, Quebec, Canada. Methods Pitfall traps, ANOVA, MIXED procedure in sas®, post hoc Tukey's adjustment, rarefaction estimates, sum-of-squares and distance-based multivariate regression trees (ssMRT, dbMRT). Results Estimates of species richness using rarefaction were highest in clearcut and two-gap treatments, decreased in smaller and more numerous gaps and were significantly higher in scarified areas than in unscarified areas. ANOVA indicated a significant impact of harvesting on the overall standardized catch. Post hoc Tukey's tests indicated that the total catch of all rove beetles was significantly higher in uncut forests than in the treated areas. Both sum-of-squares and distance-based multivariate regression trees indicated that community structure of rove beetles differed among treatments. Assemblages were grouped into (a) control plots, (b) four- and eight-gap treatments and (c) two-gap and clearcut treatments. Main conclusions Rove beetle composition responded significantly to increasing gap size. Composition among intermediate and small-sized gap treatments (four- and eight-gap treatments) was more similar to uncut control forests than were larger gap treatments (two-gap) and clearcuts. Effects of scarification were nested within the harvested treatments. When the total area of forest removed is held constant, smaller, more numerous gaps are more similar to uncut control stands than to larger gaps and falls more closely within the natural forest heterogeneity. [source]

Invasion of Agave species (Agavaceae) in south-east Spain: invader demographic parameters and impacts on native species

DIVERSITY AND DISTRIBUTIONS, Issue 5-6 2004
Ernesto I. Badano
ABSTRACT Several mechanisms have been proposed to explain the success of invasive species in new environments. A species may become invasive when a new site provides the potential for positive rates of population growth. This may be the case of several Agave species introduced to Spain in the 1940s. In this paper we document factors that promote large increases of populations of these species, and their effects on native plant communities in two sites of SE Spain. Results showed higher rhizome and bulbil production, and higher establishment rates by agaves in sandy soils than in clay soils. In their native habitats, agaves have low establishment rates and sandy soils are rare. This suggests that sandy soils are an opportunity which releases the clonal reproduction of Agave. The effects of agaves on the physiological performance and reproduction of native species were negative, positive or neutral, depending on the size and rooting depth of neighbours. Assemblages of native species growing within Agave stands had lower diversity than non-invaded sites. Our data show that Agave stands have positive growth rates in SE Spain, and suggest that sandy soils are a niche dimension enhancing the invasion in these new habitats. [source]

Climatic stress, food availability and human activity as determinants of endemism patterns in the Mediterranean region: the case of dung beetles (Coleoptera, Scarabaeoidea) in the Iberian Peninsula

DIVERSITY AND DISTRIBUTIONS, Issue 5 2002
José R. Verdú
Abstract. A study to assess the influence of abiotic (climatic conditions) and biotic factors (food resources, habitat preference and human activity) on endemism patterns of dung beetles in the Mediterranean region was conducted in the Iberian Peninsula and the Balearic Islands. The Thermicity Index (It), the Mediterraneity Index (Im3) and the Aridity Index (Ia) were used to assess the influence of abiotic factors. Relative rabbit density (DR), the proportion of landscape used historically for grazing by sheep and goats and the nature of the food resource were used to assess the influence of biotic factors. Relative endemism (EN) of dung beetle assemblages was positively and significantly related with all of the factors considered. However, the Aridity and Mediterraneity Indices are the best predictors of EN. The predicted endemism (EN = 0.017 Ia + 0.004 Im3 + 0.422) was highly positively and significantly related with the observed endemism. Dung beetle assemblages with the highest relative endemism were observed in the south-eastern part of the Iberian Peninsula. This distribution corresponded to the highest Aridity and Mediterraneity. In contrast, dung beetle assemblages with lower endemism were located in more humid and temperate areas. Assemblages of dung beetles with the highest endemism comprise many species adapted to aridity and the exploitation of dry dung pellets. Conservation of traditional grazing activity by pellet-dropping sheep and goats might benefit the maintenance of dung beetle biodiversity in Mediterranean ecosystems. [source]

Environmental features influencing Carabid beetle (Coleoptera) assemblages along a recently deglaciated area in the Alpine region

ECOLOGICAL ENTOMOLOGY, Issue 6 2007
MAURO GOBBI
Abstract 1.,The spatio-temporal approach was used to evaluate the environmental features influencing carabid beetle assemblages along a chronosequence of an Italian Alpine glacier foreland. The influence of environmental variables on species richness, morphology (wing and body length), and distribution along the chronosequence was tested. 2.,Species richness was found to be a poor indicator of habitat due to weak influences by environmental variables. It seems that the neighbouring habitats of a glacier foreland are not able to determine significant changes in carabid species richness. 3.,Instead it appears that history (age since deglaciation) and habitat architecture of a glacier foreland are strongly correlated to species adaptive morphological traits, such as wing morphology and body length. Assemblages characterised by species with reduced wing size are linked to the older stages of the chronosequence, where habitat is more structured. Assemblages characterised by the largest species are linked to the younger sites near the glacier. These morphological differentiations are explained in detail. 4.,Habitat age can therefore be considered the main force determining assemblage composition. On the basis of the relationship between morphological traits and environmental variables, it seems likely that age since deglaciation is the main variable influencing habitat structure (primary effect) on the Forni foreland. The strong relationship between carabid assemblages and habitat type indicates that site age has but a secondary effect on carabid assemblages. This may be utilised to interpret potential changes in assemblages linked to future glacier retreat. [source]

Groundfish species diversity and assemblage structure in Icelandic waters during recent years of warming

FISHERIES OCEANOGRAPHY, Issue 1 2010
LILJA STEFANSDOTTIR
Abstract Elevated ocean temperatures have been predicted to lead to a poleward shift in the latitudinal distribution ranges of fish species. Different responses of fish species to increased temperatures might lead to changes in assemblage structure and local species richness. In this study, the assemblage structure and diversity of groundfish in Icelandic waters were examined using data from a standardized groundfish survey conducted annually in 1996,2007. We used hierarchical cluster analysis to define assemblages in two time periods and canonical correspondence analysis to explore the relationships between the assemblages and temperature, depth, latitude, longitude and year. We further used two estimates of diversity, species richness and the Shannon index. Four major species assemblages were identified. Assemblages in the hydrographically stable deep waters north of the country were consistent during the study, while assemblage structure in the more variable shallow waters underwent some changes. For this period of generally increasing sea temperature, the canonical correspondence analysis also revealed a shift towards species representative of warmer temperatures. Diversity was shown to be highly variable both temporally and spatially, and also to vary with depth and temperature. Species richness increased with temperature and time southwest of the country, but decreased northeast of the country. The different trends detected between the northern and southern areas illustrate the importance of performing analyses at the most appropriate scale. [source]

Larval fish assemblages and water mass structure off the oligotrophic south-western Australian coast

FISHERIES OCEANOGRAPHY, Issue 1 2008
B. A. MUHLING
Abstract Larval fish assemblages were sampled using replicated oblique bongo net tows along a five-station transect extending from inshore (18 m depth) to offshore waters (1000 m depth) off temperate south-western Australia. A total of 148 taxa from 93 teleost families were identified. Larvae of Gobiidae and Blenniidae were abundant inshore, while larvae of pelagic and reef-dwelling families, such as Clupeidae, Engraulidae, Carangidae and Labridae were common in continental shelf waters. Larvae of oceanic families, particularly Myctophidae, Phosichthyidae and Gonostomatidae, dominated offshore assemblages. Multivariate statistical analyses revealed larval fish assemblages to have a strong temporal and spatial structure. Assemblages were distinct among seasons, and among inshore, continental shelf and offshore sampling stations. Inshore larval fish assemblages were the most seasonal, in terms of species composition and abundance, with offshore assemblages the least seasonal. However, larval fish assemblages were most closely correlated to water mass, with species distributions reflecting both cross-shelf and along-shore oceanographic processes and events. Similarity profile (SIMPROF) analysis suggested the presence of twelve distinct larval fish assemblages, largely delineated by water depth and season. The strength and position of the warm, southward flowing Leeuwin Current, and of the cool, seasonal, northward flowing Capes Current, were shown to drive much of the variability in the marine environment, and thus larval fish assemblages. [source]

Geomorphology and fish assemblages in a Piedmont river basin, U.S.A.

FRESHWATER BIOLOGY, Issue 11 2003
D. M. Walters
Summary 1.,We investigated linkages between fishes and fluvial geomorphology in 31 wadeable streams in the Etowah River basin in northern Georgia, U.S.A. Streams were stratified into three catchment sizes of approximately 15, 50 and 100 km2, and fishes and geomorphology were sampled at the reach scale (i.e. 20,40 times stream width). 2.,Non-metric multidimensional scaling (NMDS) identified 85% of the among-site variation in fish assemblage structure and identified strong patterns in species composition across sites. Assemblages shifted from domination by centrarchids, and other pool species that spawn in fine sediments and have generalised food preferences, to darter-cyprinid-redhorse sucker complexes that inhabit riffles and runs, feed primarily on invertebrates, and spawn on coarser stream beds. 3.,Richness and density were correlated with basin area, a measure of stream size, but species composition was best predicted (i.e. |r| between 0.60,0.82) by reach-level geomorphic variables (stream slope, bed texture, bed mobility and tractive force) that were unrelated to stream size. Stream slope was the dominant factor controlling stream habitat. Low slope streams had smaller bed particles, more fines in riffles, lower tractive force and greater bed mobility compared with high slope streams. 4.,Our results contrast with the ,River Continuum Concept' which argues that stream assemblages vary predictably along stream size gradients. Our findings support the ,Process Domains Concept', which argues that local-scale geomorphic processes determine the stream habitat and disturbance regimes that influence stream communities. [source]

Assembly rules and functional groups at global biogeographical scales

FUNCTIONAL ECOLOGY, Issue 5 2002
D. R. Bellwood
Summary 1The taxonomic and functional composition of reef fish assemblages are quantified in three biogeographical regions: Great Barrier Reef, French Polynesia and Caribbean. Assemblages are described in three habitats of differing wave exposure. Functional abilities are estimated based on published analyses linking fin morphology and swimming performance. 2Two questions were addressed: (1) To what extent are labrid assemblages similar among habitats and regions? (2) To what extent are functional characteristics of fish assemblages shaped by differences in biodiversity, evolutionary history and species composition? 3All three regions display highly congruent patterns of habitat use, in terms of assemblage structure and functional characteristics, despite a five-fold difference in species richness, limited or no species overlap, and a 3·2-Myear history of isolation. Exposed reef crest assemblages were dominated by fishes with fins reflecting lift-based high-speed locomotion. In contrast to abundance-based patterns, species presence/absence data were uninformative. 4The relationship between swimming ability and habitat use reveals underlying assembly rules at a functional level, emphasizing the utility of functional attributes as a metric for comparing system-level properties in taxonomically distinct faunas. [source]

The hidden record: Late Holocene landscapes and settlement archaeology in the Lower Ohio River Valley

GEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 2 2002
C. Russell Stafford
From extensive backhoe trenching and coring in the Great Miami,Ohio River confluence region, in conjunction with a large suite of radiocarbon ages, we have identified large tracts of late Holocene alluvium. Thick blankets of Historic alluvium (post-settlement) may also cover levees of the Ohio River. In conjunction with other studies in the Outer Bluegrass Region of the lower Ohio River valley, it is possible to document an association between floodplain Mollisols, Inceptisols, and Entisols and late Holocene-aged landforms. Levees appear to have stabilized between 1000 and 2000 yr B.P. Although buried soils are rare, archaeological materials were ubiquitous in late Holocene Landform Sediment Assemblages. Because a substantial volume of valley fill is late Holocene in age, Woodland sites of all types are frequently buried, and Fort Ancient sites may be buried by Historic alluvium. Therefore, if Woodland or later settlement studies in this region are based on surface evidence alone, they are likely to be biased. © 2002 John Wiley & Sons, Inc. [source]

Island Biocultural Assemblages , The Case of Kinmen Island

GEOGRAFISKA ANNALER SERIES B: HUMAN GEOGRAPHY, Issue 4 2003
Huei-Min Tsai
ABSTRACT A growing mass of research contributes to our understanding of how biological and cultural diversity are related in complex and important ways. This paper presents an assembling process of biodiversity and cultural diversity on an island, Kin-men (Quemoy), based on 1600 years of its environmental history. The study shows that the island's biocultural assemblages are a result both of external relations with the island's surrounding environment and internal relations within the island's changing human ecology. Distant political powers and economic forces are the two major external influences that have affected the flow of natural and cultural elements to and from the island, while ,screening effects' and ,isolation effects' are two factors that explain internal interactions. The island's biocultural assembling processes reveal that the openness of the island facilitates increase in the diversity of biocultural elements, while its less disturbed isolated condition fosters natural succession and co-evolution. The study suggests that biocultural assemblages and the associated processes of co-evolution and nature,society interactions are accomplished through the intermittent opportunities purposively provided by or inadvertently found in the openings and closures of boundaries, setting the scene for both boundary crossings and bounded shelter, by intent or chance. [source]

Tubular and Twisted Ni,P Fibers Molded from Morphology-Tunable and Recyclable Organic Templates of Hydrogen-Bonded Supramolecular Assemblages,

ADVANCED MATERIALS, Issue 2 2005
M. Nakagawa
Morphology-controlled nickel, phosphorus hollow microfibers (see Figure) have been fabricated by electroless plating using hydrogen-bonded fibrous molecular aggregates as novel morphology-tunable and recyclable templates. The inner diameter and the tubular morphology are tunable by simply varying the amphoteric azopyridine carboxylic acids forming the fibrous molecular aggregates. [source]

Temporal Variations in Fine Sand Assemblages in the North Aegean Sea (Eastern Mediterranean)

INTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 2 2004
Evdokia Kourelea
Abstract Two sites were selected in the North Aegean Sea for the study of shallow fine sand assemblages, which are poorly known in the Eastern Mediterranean. The biomonitoring of these sites can provide useful information on the impact of human activities on the macrofaunal and meiofaunal composition of these assemblages. In order to examine this impact, sampling took place in five different periods between 2000 and 2001. The qualitative and quantitative compositions of the communities at the two sites showed certain differences, mostly between the sites and the year of sampling rather than between sampling periods, which would be the expected outcome. The communities seem to be affected by a combination of the human activities with the particular hydrodynamics of the studied sites. [source]

Influence of Environmental Heterogeneity on the Structure of Testate Amoebae (Protozoa, Rhizopoda) Assemblages in the Plankton of the Upper Paraná River Floodplain, Brazil

INTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 2 2003
Luiz Felipe Machado Velho
Abstract In freshwater environments, testate amoebae are usually found associated with macrophytes and sediments and many studies have suggested that their occurrence in plankton samples is accidental. This implies that predictable patterns detected in planktonic assemblages should not be observed in testate amoebae assemblages. This hypothesis was tested in this study. Plankton samples were collected from different environments in the Upper Paraná River floodplain. Results show that patterns in species composition and abundance of testate amoebae are predictable, and that dominant species tend to present characteristic shell morphology in hydrologically different environments. We suggest that testate amoebae must be routinely included in plankton ecology studies, at least in floodplain environments. [source]

Assemblages of soil macrofauna across a Scottish land-use intensification gradient: influences of habitat quality, heterogeneity and area

JOURNAL OF APPLIED ECOLOGY, Issue 6 2005
PAUL EGGLETON
Summary 1Land-use intensification strongly influences biodiversity by altering habitat heterogeneity, the distribution of habitat types and their extent. This study explores these effects within mixed semi-natural/agricultural mosaic habitats in Scotland, examining the effect of land-use intensification on the soil macrofauna at point (m2), landscape (km2) and regional (> 1 km2) scales. 2The soil macrofauna in six 1-km2 sampling areas (land-use units; LUU) were sampled using a combined hand-sorting and Winkler bag extraction technique. Within each LUU, 16 1-m2 samples were taken in each of 2 successive years. Each LUU had a mixture of land-use types, representing an agricultural intensification gradient. 3The following hypotheses were tested: (i) the study area sustains a number of distinct habitats as defined by soil macrofaunal composition; (ii) a greater number of restricted range species are found in semi-natural habitats; (iii) local (point) species density is related to habitat type; (iv) overall levels of species richness per habitat at regional scales are related to species-area effects; and (v) landscape-level species density is correlated with habitat heterogeneity. 4Initial analysis revealed five distinct habitat types: Caledonian forest (semi-natural pine forest), closed canopy woodland (pine plantation and broadleaved woodland), riparian habitats (wet woodland and grassland), pasture (improved grassland) and arable (crop fields). 5As hypothesized, the Caledonian habitat contained a greater number of restricted-range species than the other habitats. However, conifer plantations contained more restricted range species than expected, given their anthropogenic origin. Species density per m2 was most strongly affected by habitat type. At the regional level, the size of the species pool was correlated with the size of habitat areas. There were more species overall in LUU with greater habitat heterogeneity. 6Synthesis and applications. Caledonian pine forests have high species densities and contain species of conservation value. Mixed conifer plantations also appear to have a surprisingly high invertebrate conservation value. In contrast, intensively managed agricultural habitats have low species densities and conservation value. Generally, mixed land-use areas have higher species densities than single land-use areas. This emphasizes the need for careful management of forest systems within the matrix of agricultural habitats to maximize landscape diversity. [source]

Spiders as potential indicators of elephant-induced habitat changes in endemic sand forest, Maputaland, South Africa

AFRICAN JOURNAL OF ECOLOGY, Issue 2 2010
Charles R. Haddad
Abstract Elephant impacts on spider assemblages, and the potential use of spiders as indicators of habitat changes was assessed in central Maputaland, South Africa. Three habitats, namely undisturbed sand forest, elephant disturbed sand forest and mixed woodland, were sampled. To ensure a thorough representation of all spider guilds, spiders were collected by tree beating, sweep netting, active searching, leaf litter sifting and pitfall traps. In total, 2808 individual spiders, representing 36 families, 144 determined genera and 251 species were collected. Spider abundance was highest in the undisturbed sand forest (n = 1129, S = 179), followed by elephant disturbed sand forest (n = 1006, S = 165) and mixed woodland (n = 673, S = 171). Assemblages of the two sand forests were more similar than to the mixed woodland assemblage. Active hunting species were indicators of the more open vegetation of elephant disturbed sand forest (six active hunters, no web-builders) and mixed woodland (ten active hunters, one web-builder), whereas web-builders are indicators of the dense, complex vegetation structure of undisturbed sand forest (six web-builders, three active hunters). Elephant-induced changes to the vegetation structure in this high diversity, high endemism region result in changes in the composition of spider assemblages, and may need to be mitigated by management intervention. Résumé L'impact des éléphants sur les assemblages d'araignées, et l'utilisation éventuelle des araignées comme indicateurs de changements des habitats, ont étéévalués dans le centre du Maputaland, en Afrique du Sud. Trois habitats ont étééchantillonnés, à savoir la forêt sableuse intacte, la forêt sableuse perturbée par des éléphants et la forêt mixte. Pour garantir une représentation complète de toutes les guildes d'araignées, on a récolté des araignées en frappant sur les arbres, en agitant des filets, en pratiquant une recherche active, en tamisant la litière de feuilles, et avec des pièges. Au total, on a récolté 2 808 araignées; représentant 36 familles, 144 genres déterminés et 251 espèces. L'abondance d'araignées était la plus grande dans la forêt sableuse non perturbée (n = 1129, S = 179), suivie par la forêt sableuse perturbée par les éléphants (n = 1006, S = 165), puis par la forêt mixte (n = 673, S = 171). Les assemblages des deux forêts sableuses étaient plus semblables entre eux qu'avec celui de la forêt mixte. Les espèces d'araignées qui chassent activement étaient des indicateurs de la végétation plus ouverte de la forêt perturbée par les éléphants (six chasseurs actifs, aucun constructeur de toile) et de la forêt mixte (dix chasseurs actifs, un constructeur de toile), alors que les constructeurs de toile étaient des indicateurs de la structure dense et complexe de la végétation de la forêt sableuse intacte (six constructeurs de toile, trois chasseurs actifs). Les éléphants induisaient des changements dans la structure de la végétation de cette région à la diversitéélevée et d'un fort endémisme, ce qui entraînait des modifications de la composition des assemblages d'araignées. Cela pourrait devoir être atténué par une intervention de la gestion. [source]

High temporal variation in the assemblage of Lepidopteran larvae on a constant resource

AFRICAN JOURNAL OF ECOLOGY, Issue 4 2009
Sini Skippari
Abstract We studied variation in the assemblage of lepidopteran larvae between individual trees, and temporal variation in the diversity and species composition of the assemblage in a medium-altitude rainforest in Kibale National Park, Uganda. Monthly samples of lepidopteran larvae were collected from the leaves of Neoboutonia macrocalyx Pax. between January 1995 and December 1996. During this period, a total of 1961 specimens representing 76 lepidopteran morphospecies were found. The numbers of individuals within species varied enormously, ranging from one to 707 individuals. Assemblages of individual trees were highly similar and dominated by geometrid larvae. Temporal variation in herbivore abundance was high. The number of individuals peaked during the major rainy season in 1995 but not in 1996 and was not correlated significantly with rainfall within these 2 years. In contrast, a negative correlation was found between lepidopteran diversity and rainfall that seems to cause a semi-annual trend in diversity with one or two peaks per year. Furthermore, there was seasonality in the similarity of the assemblage. Consequently, the same species were found in the assemblage during certain times of the year. Our study shows that short-term biodiversity assessments can give a skewed picture of the diversity of tropical forests. Résumé Nous avons étudié la variation de l'assemblage de larves de lépidoptères entre différents arbres, et la variation temporelle de la diversité et de la composition des espèces de l'assemblage dans une forêt pluviale de moyenne altitude du Parc National de Kibale, en Ouganda. Des échantillons de larves de lépidoptères furent récoltés tous les mois sur les feuilles de Neoboutonia macrocalyx Pax entre janvier 1995 et décembre 1996. Pendant cette période, nous avons trouvé un total de 1961 spécimens représentant 76 morphoespèces de Lépidoptères. Le nombre d'individus variait énormément selon les espèces, allant de un à 707 individus. Les assemblages des arbres pris individuellement étaient très comparables et dominés par les larves de géométrides. La variation temporelle de l'abondance des herbivores était importante. Le nombre d'individus a culminé lors de la principale saison des pluies de 1995, mais pas en 1996, et il n'y avait pas de corrélation significative avec les chutes de pluies ces deux années-là. Par contre, nous avons trouvé une corrélation négative entre la diversité des lépidoptères et les chutes de pluies qui semblent causer une tendance semi-annuelle de la diversité, avec un ou deux pics par an. De plus, il y avait une saisonnalité dans la similitude des assemblages. Par conséquent, la même espèce se trouvait dans les assemblages à certaines périodes de l'année. Notre étude montre que les évaluations de courte durée de la biodiversité peuvent donner une image faussée de la diversité des forêts tropicales. [source]