I.e. Species (i.e + species)

Distribution by Scientific Domains

Selected Abstracts

Temporal dynamics and nestedness of an oceanic island bird fauna

GLOBAL ECOLOGY, Issue 4 2006
Ermias T. Azeria
ABSTRACT Aim, To examine temporal variation in nestedness and whether nestedness patterns predict colonization, extinction and turnover across islands and species. Location, Dahlak Archipelago, Red Sea. Method, The distributions of land birds on 17 islands were recorded in two periods 30 years apart. Species and islands were reordered in the Nestedness Temperature Calculator, software for assessing degrees of nestedness in communities. The occupancy probability of each cell, i.e. species,island combinations, was calculated in the nested matrix and an extinction curve (boundary line) was specified. We tested whether historical and current nested ranks of species and islands were correlated, whether there was a relationship between occupancy probability (based on the historical data) and number of extinctions or colonizations (regression analyses) and whether the boundary line could predict extinctions and colonizations (chi-square analyses). Results, Historical and current nested ranks of islands and species were correlated but changes in occupancy patterns were common, particularly among bird species with intermediate incidence. Extinction and turnover of species were higher for small than large islands, and colonization was negatively related to isolation. As expected, colonizations were more frequent above than below the boundary line. Probability of extinction was highest at intermediate occupancy probability, giving a quadratic relationship between extinction and occupancy probability. Species turnover was related to the historical nested ranks of islands. Colonization was related negatively while extinction and occupancy turnover were related quadratically to historical nested ranks of species. Main conclusions, Some patterns of the temporal dynamics agreed with expectations from nested patterns. However, the accuracy of the predictions may be confounded by regional dynamics and distributions of idiosyncratic, resource-limited species. It is therefore necessary to combine nestedness analysis with adequate knowledge of the causal factors and ecology of targeted species to gain insight into the temporal dynamics of assemblages and for nestedness analyses to be helpful in conservation planning. [source]

Recent innovations in marine biology

Ferdinando Boero
Abstract Modern ecology arose from natural history when Vito Volterra analysed Umberto D'Ancona's time series of Adriatic fisheries, formulating the famous equations describing the linked fluctuations of a predator,prey system. The shift from simple observation to careful sampling design, and hypothesis building and testing, often with manipulative approaches, is probably the most relevant innovation in ecology, leading from descriptive to experimental studies, with the use of powerful analytical tools to extract data (from satellites to molecular analyses) and to treat them, and modelling efforts leading to predictions. However, the historical component, time, is paramount in environmental systems: short-term experiments must cope with the long term if we want to understand change. Chaos theory showed that complex systems are inherently unpredictable: equational, predictive science is only feasible over the short term and for a small number of variables. Ecology is characterized by a high number of variables (e.g. species) interacting over wide temporal and spatial scales. The greatest recent conceptual innovation, thus, is to have realized that natural history is important, and that the understanding of complexity calls for humility. This is not a return to the past, because now we can give proper value to statistical approaches aimed at formalizing the description and the understanding of the natural world in a rigorous way. Predictions can only be weak, linked to the identification of the attractors of chaotic systems, and are aimed more at depicting scenarios than at forecasting the future with precision. Ecology was originally split into two branches: autecology (ecology of species) and synecology (ecology of species assemblages, communities, ecosystems). The two approaches are almost synonymous with the two fashionable concepts of today: ,biodiversity' and ,ecosystem functioning'. A great challenge is to put the two together and work at multiple temporal and spatial scales. This requires the identification of all variables (i.e. species and their ecology: biodiversity, or autoecology) and of all connections among them and with the physical world (i.e. ecosystem functioning, or synecology). Marine ecosystems are the least impacted by human pressures, compared to terrestrial ones, and are thus the best arena to understand the structure and function of the natural world, allowing for comparison between areas with and areas without human impact. [source]

Sexual size dimorphism in Asian colobines revisited

Cyril C. Grueter
Abstract Asian colobines exhibit a wide range of sexual dimorphism in body mass. Some species are monomorphic, whereas others are strongly dimorphic. Strong sexual dimorphism is generally viewed as the consequence of intense male contest competition over access to mates, but this idea appears not to explain variation in sexual dimorphism in Asian colobines. Our results show that modular colobines, i.e. species in which social units aggregate into higher-level bands or often associate, have significantly higher levels of sexual dimorphism in body mass than the nonmodular ones. This finding was corroborated by means of phylogenetically controlled methods and multiple regression analyses. The results suggest that living in a modular society intensifies the contest competition among males, which is further exacerbated by the continuous presence of all-male units. Am. J. Primatol. 71:609,616, 2009. 2009 Wiley-Liss, Inc. [source]

Ecoregional planning in marine environments: identifying priority sites for conservation in the northern Gulf of Mexico

Michael W. Beck
Abstract 1.,The overall aim of this work was to identify sites within the northern Gulf of Mexico that, if protected, would fully represent the biological diversity of the nearshore waters of this ecoregion. In this paper, we focus on the eastern subregion, northwest Florida, to illustrate the process of ecoregional planning in marine environments. 2.,The basic steps in ecoregional planning include: identification of conservation targets, i.e. species and habitats; collection of data on their ecology and distribution; determination of conservation goals for the amount of targets that must be protected; and identification of a set of sites that meets these goals for all targets. 3.,As a preliminary goal, it was determined that the set of priority sites should contain at least 20% of the current distribution of each target habitat and species. 4.,Two primary tools were used to choose a set of priority sites: a reserve selection program, SITES, and interviews and a workshop with scientists and managers. The final set of priority sites integrated information from these various sources. 5.,The goals were exceeded for all conservation targets in the priority sites. On average, 75 and 58% of the distributions of the habitat targets were contained within the priority and high priority sites, respectively. These priority and high priority sites only occupied 29 and 17% of the study area, respectively. 6.,One of the first steps in the conservation of the bays identified as priority sites is the recognition that they are integrally linked by important processes to the surrounding terrestrial and aquatic environments. Conservation in a part of these estuarine landscapes will benefit biodiversity across environments. Copyright 2001 John Wiley & Sons, Ltd. [source]