			Home About us Contact

Different Guilds (different + guild)

Distribution by Scientific Domains

Life Sciences	50%
Earth and Environmental Science	50%

Selected Abstracts

Intense drilling in the Carboniferous brachiopod Cardiarina cordata Cooper, 1956

LETHAIA, Issue 2 2003
ALAN P. HOFFMEISTER
The brachiopod Cardiarina cordata, collected from a Late Pennsylvanian (Virgilian) limestone unit in Grapevine Canyon (Sacramento Mts., New Mexico), reveals frequent drillings: 32.7% (n = 400) of these small, invariably articulated specimens (<2 mm size) display small (<0.2 mm), round often beveled holes that are typically single and penetrate one valve of an articulated shell. The observed drilling frequency is comparable with frequencies observed in the Late Mesozoic and Cenozoic. The drilling organism displayed high valve and site selectivity, although the exact nature of the biotic interaction recorded by drill holes (parasitism vs. predation) cannot be established. In addition, prey/host size may have been an important factor in the selection of prey/host taxa by the predator/parasite. These results suggest that drilling interactions occasionally occurred at high (Cenozoic-like) frequencies in the Paleozoic. However, such anomalously high frequencies may have been restricted to small prey/host with small drill holes. Small drillings in C. cordata, and other Paleozoic brachiopods, may record a different guild of predators/parasites than the larger, but less common, drill holes previously documented for Paleozoic brachiopods, echinoderms, and mollusks. [source]

Response of waterbird species to fluctuating water levels in tropical coastal wetlands

AFRICAN JOURNAL OF ECOLOGY, Issue 3 2010
Francis Gbogbo
Abstract Recent upsurges in the incidence of dam construction over rivers for farming and hydro electric power in the West African sub-region is a known promoter of fluctuating water levels on tropical coastal wetlands. Waterbirds, being one of the dominant fauna on wetlands, are key species that can be affected by fluctuating water levels. Waterbird census and water level monitoring at four coastal wetlands in Ghana revealed that different guilds (species assemblages) of waterbirds responded differently to fluctuating water levels. The populations density of birds in guilds 1 (ducks and cormorants), 3 (tactile surface foraging waders), 4 (pelagic foraging waders) and 5 (stalking herons and egrets) significantly (P < 0.05) increased linearly with decreasing water levels. The population density of birds in guilds 2 (visual surface foraging waders) and 7 (fishing terns) responded significantly (P < 0.05) in a second order polynomial function with optimum numbers occurring when water levels were neither too high nor too low. As far as farming and energy requirement are met from these dams, it is important that the ecological needs of waterbirds on wetlands are incorporated into the management of these dams so as to maintain appropriate water levels beneficial to waterbird populations. Résumé En Afrique de l'Ouest, la multiplication récente des constructions de barrages sur des cours d'eau pour les exploitations agricoles et la fourniture d'électricité est un facteur connu des fluctuations du niveau d'eau dans les zones humides côtières tropicales. Les oiseaux d'eau, éléments dominants de la faune des zones humides, sont des espèces clés qui peuvent être touchées par la fluctuation du niveau de l'eau. Les recensements des oiseaux d'eau et le suivi du niveau de l'eau dans quatre zones humides côtières du Ghana ont révélé que des guildes (assemblages d'espèces) différentes répondaient différemment à la fluctuation du niveau de l'eau. La densité de population des oiseaux dans les guildes 1 (canards et cormorans), 3 (échassiers se nourrissant en surface grâce aux corpuscules tactiles du bec), 4 (échassiers se nourrissant en profondeur) et 5 (hérons et aigrettes qui pêchent à l'affût) augmentait significativement (P < 0,05) de façon linéaire lorsque le niveau de l'eau baissait. La population des oiseaux des guildes 2 (échassiers chassant à vue à la surface) et 7 (sternes pêcheuses) répondait significativement (P < 0,05) dans une fonction polynômiale du 2d degré, les nombres optimum s'observant lorsque le niveau de l'eau n'est ni trop haut ni trop bas. À partir du moment où les exigences de l'agriculture et de l'énergie sont satisfaites grâce à ces barrages, il est important que les besoins écologiques des oiseaux d'eau des zones humides soient intégrés dans la gestion de ces barrages de façon à maintenir des niveaux d'eau favorables aux populations d'oiseaux d'eau. [source]

Release from foliar and floral fungal pathogen species does not explain the geographic spread of naturalized North American plants in Europe

JOURNAL OF ECOLOGY, Issue 3 2009
Mark Van Kleunen
Summary 1During the last centuries many alien species have established and spread in new regions, where some of them cause large ecological and economic problems. As one of the main explanations of the spread of alien species, the enemy-release hypothesis is widely accepted and frequently serves as justification for biological control. 2We used a global fungus,plant host distribution data set for 140 North American plant species naturalized in Europe to test whether alien plants are generally released from foliar and floral pathogens, whether they are mainly released from pathogens that are rare in the native range, and whether geographic spread of the North American plant species in Europe is associated with release from fungal pathogens. 3We show that the 140 North American plant species naturalized in Europe were released from 58% of their foliar and floral fungal pathogen species. However, when we also consider fungal pathogens of the native North American host range that in Europe so far have only been reported on other plant species, the estimated release is reduced to 10.3%. Moreover, in Europe North American plants have mainly escaped their rare, pathogens, of which the impact is restricted to few populations. Most importantly and directly opposing the enemy-release hypothesis, geographic spread of the alien plants in Europe was negatively associated with their release from fungal pathogens. 4Synthesis. North American plants may have escaped particular fungal species that control them in their native range, but based on total loads of fungal species, release from foliar and floral fungal pathogens does not explain the geographic spread of North American plant species in Europe. To test whether enemy release is the major driver of plant invasiveness, we urgently require more studies comparing release of invasive and non-invasive alien species from enemies of different guilds, and studies that assess the actual impact of the enemies. [source]

Restoring prairie pothole wetlands: does the species pool concept offer decision-making guidance for re-vegetation?

APPLIED VEGETATION SCIENCE, Issue 2 2006
Susan M. Galatowitsch
Anon. (2004) Abstract Question: Do regional species pools, landscape isolation or on-site constraints cause plants from different guilds to vary in their ability to colonize restored wetlands? Location: Iowa, Minnesota, and South Dakota, USA. Methods: Floristic surveys of 41 restored wetlands were made three and 12 years after reflooding to determine changes in local species pools for eight plant guilds. The effect of landscape isolation on colonization efficiency was evaluated for each guild by plotting local species pools against distance to nearby natural wetlands, and the relative importance of dispersal vs. on-site constraints in limiting colonization was explored by comparing the local species pools of restored and natural wetlands within the region. Results: Of the 517 wetland plant taxa occurring in the region, 50% have established within 12 years. The proportion of the regional species pool represented in local species pools differed among guilds, with sedge-meadow perennials, emergent perennials and floating/submersed aquatics least represented (33-36%) and annual guilds most represented (74-94%). Colonization-to-extinction ratios suggest that floating/submersed aquatics have already reached a species equilibrium while sedge-meadow and emergent perennials are still accumulating species. Increasing distance to nearest wetlands decreased the proportion of the regional species pool present in local pools for all guilds except native annuals and woody plants. The maximum proportion predicted, assuming no distance constraint, was comparable to the lowest-diversity natural wetlands for most perennial guilds, and also lower than what was achieved in a planted, weeded restoration. Conclusions: A biotic constraints seem to limit the colonization of floating/submersed aquatics into natural or restored wetlands, whereas all other guilds are potentially constrained by dispersal or biotic factors (i.e. competition from invasive species). Using species pools to evaluate restoration progress revealed that immigration potential varies considerably among guilds, that local species richness does not necessarily correspond to immigration limitations, and that some guilds (e.g. sedge-meadow perennials) will likely benefit more than others from being planted at restoration sites. [source]