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Life-history Attributes (life-history + attribute)
Selected AbstractsLatitudinal patterns in abundance and life-history traits of the mole crab Emerita brasiliensis on South American sandy beachesDIVERSITY AND DISTRIBUTIONS, Issue 2 2004Omar Defeo ABSTRACT Demographic and life-history attributes of the mole crab Emerita brasiliensis were analysed along 2700 km of the Atlantic coast of South America, including sandy beaches at the southernmost limit (Uruguay) and at the core of its geographical range (Brazil). Population features varied markedly within this range and exhibited systematic geographical patterns of variation. Abundance significantly increased from temperate to subtropical beaches, and the same held true for the asymptotic weight of males. Conversely, length at maturity and asymptotic weight of females increased from subtropical to temperate beaches, being inversely related to sea water temperature. Macroecological patterns in abundance and body weight showed the first large-scale evidence of scaling of population density to body size for a sandy beach population. Mortality rates (both sexes) followed a nonlinear increase from low-density temperate beaches to high-density subtropical beaches. The effect of habitat quality and availability could explain discontinuities in the species distribution within its range, and also differential responses in life-history attributes at a local scale. Asymmetries and converse latitudinal trends between sexes suggest that there is not a single general factor determining large-scale patterns in life-history traits of this species. Our results reinforce the view that density-dependent and environmental factors operating together regulate sandy beach populations. The need to develop macroecological studies in sandy beach ecology is highlighted, as knowledge acquired from local to large spatial scales throws light on population structure and regulation mechanisms. [source] Host plants and butterfly biology.ECOLOGICAL ENTOMOLOGY, Issue 1 2004Do host-plant strategies drive butterfly status? Abstract., 1.,To determine whether rarity and decline is linked to organism ecology, associations have been examined between butterfly larval host-plant competitive, stress-tolerant, ruderal (C-S-R) strategies and butterfly biology. 2.,Associations have been sought between mean C-S-R scores for larval host plants with butterfly life history, morphology and physiology variables, resource use, population attributes, geography, and conservation status. Comparisons are carried out across species and controlled for phylogenetic patterning. 3.,Butterfly biology is linked to host-plant strategies. An increasing tendency of a butterfly's host plants to a particular strategy biases that butterfly species to functionally linked life-history attributes and resource breadth and type. In turn, population attributes and geography are significantly and substantially affected by host choice and the strategies of these host plants. 4.,The greatest contrast is between butterfly species whose host plants are labelled C and R strategists and those whose host plants are labelled S strategists. Increasingly high host-plant C and R strategy scores bias butterflies to rapid development, short early stages, multivoltinism, long flight periods, early seasonal emergence, higher mobility, polyphagy, wide resource availability and biotope occupancy, open, areally expansive, patchy population structures, denser distributions, wider geographical ranges, resistance to range retractions as well as to increasing rarity in the face of environmental changes. Increasing host-plant S strategy scores have reversed tendencies, biasing those butterfly species to extended development times, fewer broods, short flight periods, smaller wing expanse and lower mobility, monophagy, restricted resource exploitation and biotope occupancy, closed, areally limited populations with typical metapopulation structures, sparse distributions, and limited geographical ranges, range retractions, and increased rarity. 5.,Species with S strategy host plants are species vulnerable to current environmental changes and species of conservation concern. [source] Herbivory in an acid streamFRESHWATER BIOLOGY, Issue 4 2000Mark E. Ledger Summary 1Spatial and temporal variation in the distribution and feeding of non-predatory macroinvertebrates was investigated in a first-order, acid stream in the Ashdown Forest, southern England. 2Stonefly (Nemouridae) and chironomid (Orthocladiinae) larvae were abundant on the upper surfaces of mineral substrata of three sizes (small stones, large stones, bedrock). The density of larvae in each taxonomic group did not vary among substrata of different sizes, although strong seasonal variation existed. 3Nemourids and chironomids (H. marcidus) collected from the upper surfaces of substrata exhibited generalist feeding habits, consuming algae (diatoms, coccoid and filamentous green algae), detritus (biofilm matrix material and fine particulate organic matter (FPOM)) and inorganic debris. 4There was spatial variation in the gut contents of nemourids. The proportion of algae in the guts of larvae often increased with the size of the substratum from which they were collected. Strong temporal variation in the composition of the diet also existed. Nemourids ingested a large quantity of attached algae and biofilm matrix from the biofilm in spring and winter, but consumed loose FPOM and associated microflora in summer and autumn. 5We conclude that, in this acid stream, the trophic linkage between algae and grazers is maintained by ,detritivorous' stonefly and chironomid species. The relationship between the feeding habits of these larvae and other life-history attributes, such as mouthpart morphology and mobility, is discussed. [source] Floral free fall in the Swiss lowlands: environmental determinants of local plant extinction in a peri-urban landscapeJOURNAL OF ECOLOGY, Issue 4 2007IVANA STEHLIK Summary 1Local floras are being depleted by a host of human activities, including habitat destruction and fragmentation, eutrophication, and the intensification of agriculture. Species with particular ecological demands or life-history attributes are more prone to extinction than species with a broader niche. 2We used an old herbarium from the municipality of Küsnacht (Swiss lowlands) as a historical record for comparison with contemporary plant diversity. This comparison revealed that 17% to 28% of all vascular plants that occurred between 1839 and 1915 were extinct by 2003. 3Species of different habitats and life-forms had significantly different rates of extinction: wetlands, disturbed sites and meadows lost most species, whereas forests and rocky habitats were least affected; aquatics and annuals were most prone to extinction, geophytes and hemicryptophytes were intermediate, and phanerophytes and chamaephytes were least affected. 4Species adapted to nutrient-poor soils suffered highest extinction in all habitats, indicating that eutrophication poses an urgent threat to species diversity. Light and soil moisture requirements also had significant effects on extinction, but the direction of the effect varied by habitat. 5When species were grouped into IUCN categories of the red list of Switzerland, the rank order of the observed extinction matched the red list assignment. 6Because many of the remaining species had high estimated extinction probabilities and because extinction is often delayed (extinction debt), a substantial part of the remaining flora of Küsnacht is likely to go extinct in the near future. This will increase the dominance of the common species that already comprise 81% of the local flora. 7The rates and patterns of extinction in Küsnacht are probably representative of surrounding Swiss lowlands and peri-urban landscapes in most developed countries. Studies such as ours can serve as a call for action and form a basis for future monitoring of biodiversity. [source] Spatial patterns of the biological traits of freshwater fish communities in south-west FranceJOURNAL OF FISH BIOLOGY, Issue 2 2005F. Santoul Spatial patterns in the combinations of biological traits of fish communities were studied in the Garonne River system (57 000 km2, south-west France). Fish species assemblages were recorded at 554 sampling sites, and the biological traits of species were described using a fuzzy-coding method. A co-inertia analysis of species distributions and biological traits identified some spatial patterns of species trait combinations. Fish species richness progressively increased from up- to downstream sections, and the longitudinal patterns of fish assemblages partitioned the river into clear biogeographic areas, such as the brown trout Salmo trutta(headwater streams), the grayling Thymallus thymallus, the barbel Barbus barbus and the bream Abramis brama zones (most downstream sections), which fitted with Huet's well-known zonation for western European rivers. Only a few biological traits, chiefly related to life-history attributes, significantly influenced the observed fish distributions. Fecundity, potential size, maximum age and reproductive factor increased from headwater to plain reaches. As a theoretical framework for assessing and predicting the functional organization of stream fish communities, spatial variations in species traits can be related to habitat conditions, thus providing explicit spatial schemes that may be useful to the design of both scientific studies and river management. 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