Species richness

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

Global patterns of diversity and community structure in marine bacterioplankton

Abstract: Because of their small size, great abundance and easy dispersal, it is often assumed that marine planktonic microorganisms have a ubiquitous distribution that prevents any structured assembly into local communities. To challenge this view, marine bacterioplankton communities from coastal waters at nine locations distributed world-wide were examined through the use of comprehensive clone libraries of 16S ribosomal RNA genes, used as operational taxonomic units (OTU). Our survey and analyses show that there were marked differences in the composition and richness of OTUs between locations. Remarkably, the global marine bacterioplankton community showed a high degree of endemism, and conversely included few cosmopolitan OTUs. Our data were consistent with a latitudinal gradient of OTU richness. We observed a positive relationship between the relative OTU abundances and their range of occupation, i.e. cosmopolitans had the largest population sizes. Although OTU richness differed among locations, the distributions of the major taxonomic groups represented in the communities were analogous, and all local communities were similarly structured and dominated by a few OTUs showing variable taxonomic affiliations. The observed patterns of OTU richness indicate that similar evolutionary and ecological processes structured the communities. We conclude that marine bacterioplankton share many of the biogeographical and macroecological features of macroscopic organisms. The general processes behind those patterns are likely to be comparable across taxa and major global biomes.

Toward a Mechanistic Understanding and Prediction of Biotic Homogenization

Abstract: The widespread replacement of native species with cosmopolitan, nonnative species is homogenizing the global fauna and flora. While the empirical study of biotic homogenization is substantial and growing, theoretical aspects have yet to be explored. Consequently, the breadth of possible ecological mechanisms that can shape current and future patterns and rates of homogenization remain largely unknown. Here, we develop a conceptual model that describes 14 potential scenarios by which species invasions and/or extinctions can lead to various trajectories of biotic homogenization (increased community similarity) or differentiation (decreased community similarity); we then use a simulation approach to explore the model’s predictions. We found changes in community similarity to vary with the type and number of nonnative and native species, the historical degree of similarity among the communities, and, to a lesser degree, the richness of the recipient communities. Homogenization is greatest when simil...

Measuring and Estimating Species Richness, Species Diversity, and Biotic Similarity from Sampling Data

Abstract: This article reviews modern statistical approaches to estimating species diversity and biotic similarity from empirical samples of species abundance or incidence Key methods include rarefaction, extrapolation, and non-parametric estimation of the asymptote of species richness Hill numbers are presented as unifying indices of species diversity that take into account the relative abundance of different species Species richness estimators, Hill numbers, and measures of biotic similarity can be extended to account for phylogenetic, taxonomic, and functional diversity of biological assemblages These statistical methods control for sampling effects in biodiversity data and can be applied to many important questions in ecology

Species divergence and the measurement of microbial diversity

Abstract: Diversity measurement is important for understanding community structure and dynamics, but has been particularly challenging for microorganisms. Microbial community characterization using small subunit rRNA (SSU rRNA) gene sequences has revealed an extensive, previously unsuspected diversity that we are only now beginning to understand, especially now that advanced sequencing technologies are producing datasets containing hundreds of thousands of sequences from hundreds of samples. Efforts to quantify microbial diversity often use taxon-based methods that ignore the fact that not all species are equally related, which can therefore obscure important patterns in the data. For example, α-diversity (diversity within communities) is often estimated as the number of species in a community (species richness), and β-diversity (partitioning of diversity among communities) is often based on the number of shared species. Methods for measuring α- and β-diversity that account for different levels of divergence between individuals have recently been more widely applied. These methods are more powerful than taxon-based methods because microorganisms in a community differ dramatically in sequence similarity, which also often correlates with phenotypic similarity in key features such as metabolic capabilities. Consequently, divergence-based methods are providing new insights into microbial community structure and function.

The Role of Habitat Complexity and Heterogeneity in Structuring Tropical Mammal Communities

Abstract: The relationship between mammal community structure and vertical variation in habitat physiognomy (complexity) and horizontal variation in habitat form (heterogeneity) was examined on five study areas in the llanos of Venezuela. Data on the small mammal ( 38 000 trap nights from 1976—1978. Data on the distribution of large, nonvolant mammals were obtained during 24 mo of field observation. Measures of habitat complexity and habitat heterogeneity were derived using principal components analysis. There was little association between habitat structure and the richness, diversity, abundance, and biomass of small mammals. Abiotic factors, such as the degree of wet—season flooding, probably play an important role in patterns of small mammal distribution and abundance. The total number of mammal species was positively correlated with habitat complexity but not correlated with habitat heterogeneity. Increasing species richness across the complexity gradient was probably accommodated by increasing potential food resources. New species were added to complex communities primarily through guild expansion rather than guild addition.