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Species richness

About: Species richness is a research topic. Over the lifetime, 61672 publications have been published within this topic receiving 2183796 citations.


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Journal ArticleDOI
TL;DR: In this paper, the authors focus on the changes in vegetation in abandoned pastures ranging in age from 0 to 60 years or more in two replicate chronosequences and find that the initial colonizing species are not typical pioneer species (e.g. Cecropia sp., Scheffleria morotononi), but a group of shrubs and treelets in the Rubiaceae, Melastomataceae, and Myrtaceae.

376 citations

Journal ArticleDOI
03 Sep 2010-Science
TL;DR: Future assemblies of animals following mass extinction cannot be predicted by analyses of Phanerozoic fossils, and the current global crisis may permanently alter the biosphere’s taxonomic composition by changing the rules of evolution.
Abstract: The fossil record demonstrates that each major taxonomic group has a consistent net rate of diversification and a limit to its species richness. It has been thought that long-term changes in the dominance of major taxonomic groups can be predicted from these characteristics. However, new analyses show that diversity limits may rise or fall in response to adaptive radiations or extinctions. These changes are idiosyncratic and occur at different times in each taxa. For example, the end-Permian mass extinction permanently reduced the diversity of important, previously dominant groups such as brachiopods and crinoids. The current global crisis may therefore permanently alter the biosphere's taxonomic composition by changing the rules of evolution.

376 citations

Journal ArticleDOI
TL;DR: A cascading series of effects of elevation on soil fertility, anti-herbivore defences, and the level of density-dependent mortality may account for the observed drop in diversity with elevation, and would be consistent with lower β diversity and greater basal area at higher elevation.
Abstract: 1 Data on the composition, structure and diversity of plant communities were gathered along a 1000-m altitudinal transect from tropical seasonal dry forest to cloud forest on calcareous Cerro Grande in Jalisco, Mexico. 2 A total of 470 species, 292 genera and 103 families of vascular plants occurred in 43 samples of 0.1 ha, stratified at 100-m elevational intervals between 1500 and 2500 m a.s.1. There were 97 tree species, 76 shrubs, 70 vines, 181 terrestrial herbs, 39 epiphytes, 3 hemiparasites, 3 succulent rosette shrubs and 1 saprophyte. 3 Forest composition varied continuously with altitude, based on the Shipley & Keddy (1987) test, ordination via reciprocal averaging, and elevational trends in the Sorenson similarities of samples at adjacent altitudes. supporting the individualistic hypothesis of plant community organization. 4 Understorey herbs, shrubs and vines showed the greatest decline in species number with increasing altitude. This pattern is hypothesized to result from the more open, more frequently disturbed, and more completely deciduous canopies at lower, drier elevations. The proportion of evergreen woody plants was greater at higher altitudes, reflecting less seasonal aridity and greater soil leaching. The proportion of endozoochorous species increased with altitude, while the proportion of pterochorous and ectozoochorous species decreased, reflecting trends in the hypothesized efficacy of these mechanisms of seed dispersal. 5 Total basal area of woody plants > 2.5 cm d.b.h. and basal area per tree both increased roughly fourfold between 1500 and 2500 m. 6 Species richness decreased sharply with altitude, due mainly to decreases in terrestrial herbs, and (to a lesser extent) shrubs and vines. The average number of species per 0.1 ha declined from 134 at 1500 m to 43 at 2500 m. The numbers of species, genera and families per sample declined linearly with elevation. Species composition of samples within an altitudinal band showed greater horizontal turnover (β diversity) at lower elevations, showing that low-elevation forests are not only locally more diverse, but spatially more patchy. Community composition varies roughly six times as rapidly with elevation as with the same distance horizontally. 7 A cascading series of effects of elevation on soil fertility, anti-herbivore defences, and the level of density-dependent mortality may account for the observed drop in diversity with elevation, and would be consistent with lower β diversity and greater basal area at higher elevations.

375 citations

Journal ArticleDOI
01 Jul 1995-Ecology
TL;DR: The observed diversity patterns are consistent with the idea that high diversity is maintained in these habitats by an interaction between low levels of disturbance and habitat patchiness, and Huston's dynamic equilibrium model may have some validity, at least at the level of the patch.
Abstract: Invertebrate diversity patterns were examined in 11 freshwater habitats (10 streams and a windswept lake shore) of similar physicochemical nature but different thermal and hydrologic stability in the Cass-Craigieburn region, New Zealand. Species richness and density were markedly higher at the more stable sites, but species evenness peaked at sites of intermediate stability. Of the 20 environmental variables examined, a multivariate instability index incorporating temporal variation in depth, temporal variation in current speed, substrate stability, the Pfankuch channel stability index, temperature range, and stream reach tractive force was the single best predictor of the number of species, whereas epilithic pigment concentration was the single best predictor of invertebrate density. The pattern in species richness did not support any of three diversity hypotheses considered. In contrast, the pattern in species evenness suggested competitive exclusion may be occurring patchily and that Huston's dynamic equilibrium model may have some validity, at least at the level of the patch. However, the strong link between productivity and stability apparent in these habitats, and a lack of information on the effects of increased productivity on competition in stream benthic communities makes any firm assessment of the latter model difficult. The observed diversity patterns are, however, consistent with the idea that high diversity is maintained in these habitats by an interaction between low levels of disturbance and habitat patchiness.

375 citations

Journal ArticleDOI
TL;DR: A simple approach to constructing theoretical null models of bacterial species abundance provides detailed descriptions of soil bacterial community structure that can be used to guide experimental design and estimate the required survey scale to document specified fractions of community diversity.
Abstract: Understanding patterns of biodiversity in microbial communities is severely constrained by the difficulty of adequately sampling these complex systems. We illustrate the problem with empirical data from small surveys (200-member 16S rRNA gene clone libraries) of four bacterial soil communities from two locations in Arizona. Among the four surveys, nearly 500 species-level groups (Dunbar et al., Appl. Environ. Microbiol. 65:662-1669, 1999) and 21 bacterial divisions were documented, including four new candidate divisions provisionally designated SC1, SC2, SC3, and SC4. We devised a simple approach to constructing theoretical null models of bacterial species abundance. These null models provide, for the first time, detailed descriptions of soil bacterial community structure that can be used to guide experimental design. Models based on a lognormal distribution were consistent with the observed sizes of the four communities and the richness of the clone surveys. Predictions from the models showed that the species richness of small surveys from complex communities is reproducible, whereas the species composition is not. By using the models, we can now estimate the required survey scale to document specified fractions of community diversity. For example, documentation of half the species in each model community would require surveys of 16,284 to 44,000 individuals. However, quantitative comparisons of half the species in two communities would require surveys at least 10-fold larger for each community.

375 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20243
20232,454
20225,118
20213,510
20203,287
20193,254