scholarly journals An Algebraic Derivation of Chao’s Estimator of the Number of Species in a Community Highlights the Condition Allowing Chao to Deliver Centered Estimates

2014 ◽  
Vol 2014 ◽  
pp. 1-6
Author(s):  
Jean Béguinot
Keyword(s):  
Species Richness ◽  
Lower Bound ◽  
Species Abundance ◽  
Nonparametric Estimator ◽  
Species Abundance Distribution ◽  
Abundance Distribution ◽  
Limited Size ◽  
Total Species Richness ◽  
Log Normal ◽  
Total Species

Anne Chao proposed a very popular, nonparametric estimator of the species richness of a community, on the basis of a limited size sampling of this community. This expression was originally derived on a statistical basis as a lower-bound estimate of the number of missing species in the sample and provides accordingly a minimal threshold for the estimation of the total species richness of the community. Hereafter, we propose an alternative, algebraic derivation of Chao’s estimator, demonstrating thereby that Chao’s formulation may also provide centered estimates (and not only a lower bound threshold), provided that the sampled communities satisfy a specific type of SAD (species abundance distribution). This particular SAD corresponds to the case when the number of unrecorded species in the sample tends to decrease exponentially with increasing sampling size. It turns out that the shape of this “ideal” SAD often conforms approximately to the usually recorded types in nature, such as “log-normal” or “broken-stick.”. Accordingly, this may explain why Chao’s formulation is generally recognized as a particularly satisfying nonparametric estimator.

scholarly journals Variations in Total Species Richness and the Unevenness of Species Abundance Distribution between Two Distant Conus Communities (Neogastropoda): A Case Study in Mannar Gulf (India)

2019 ◽  
pp. 1-18
Author(s):  
Jean Béguinot
Keyword(s):  
Species Richness ◽  
Species Composition ◽  
Species Abundance ◽  
Species Abundance Distribution ◽  
Abundance Distribution ◽  
Marine Gastropods ◽  
Total Species Richness ◽  
Species Recruitment ◽  
Total Species

The genus Conus forms a conspicuous and rather homogeneous group within marine Gastropods. This makes it all the more interesting to focus on the sub-communities formed by Conus species and to analyze the potential specificities in the internal organization of species in these communities, in particular species richness, species abundance distribution and the effect of geographical distance between communities on differences in their respective species composition. Accordingly, two Conus communities along the coast in Mannar Gulf (India), separated by 80 km, are considered. Reliable analysis requires, first, to treat exhaustive data from complete samplings or, else – as here – to implement an appropriate extrapolation procedure to complete numerically the partial samplings. After numerical completion, substantial differences were highlighted between the two communities, not only in terms of true (total) species richness but, even more, as regards the profile and the average unevenness of the distributions of species abundance. Also, significant dissimilarity in species composition was found between the two communities, that may be tentatively attributed to either deterministic distance decay in similarity of species composition or, alternatively, to the persistence in the stochastic process of species recruitment from the regional stock of Conus planktonic larvae. This preliminary study yet requests to be complemented by other similar case studies, before drawing any safer interpretative conclusions.

Species richness in the Phanerozoic: an investigation of sampling effects

Paleobiology ◽  
1978 ◽  
Vol 4 (4) ◽  
pp. 394-406 ◽  
Author(s):  
Philip W. Signor
Keyword(s):  
Species Richness ◽  
Species Abundance ◽  
Strongly Correlated ◽  
Species Abundance Distribution ◽  
Sediment Volume ◽  
Total Species Richness ◽  
Cenozoic Sediments ◽  
The Impact ◽  
The Relationship ◽  
Total Species

Given estimates of the variation in total standing species richness through the periods of the Phanerozoic, mean species duration, and the relative intensity of the sampling of the fauna from each of the periods, the expected number of described species can be predicted for each period of the Phanerozoic using an analytic sampling model. This model is based on the assumption that the relative abundances of species in any geologic period can be approximated by the canonical (lognormal) species-abundance distribution.Three commonly cited models of standing species richness (Valentine, 1973; Gould et al., 1977; Bambach, 1977) each suggest different patterns of species richness in the Phanerozoic. By assuming that sampling of the fossil record is proportionate to sediment volume, it can be shown with the sampling model that the Empirical, Equilibrium, and Species-Richness Models each predict that the number of described species will be strongly correlated with sediment volume. Equally high correlations are predicted if it is assumed that sampling is proportionate to sediment area or to paleontological interest. The correlations predicted for each of the three models are remarkably similar. The impact of sampling effects is so strong that the variations in species richness postulated by these three models are almost completely obscured. Preservational biases will probably only further obscure the relationship between the number of described species and total species richness. Therefore, it seems likely that analysis of trends in the total number of described species will be of little use in determining trends in worldwide species richness in the Phanerozoic.Comparison of the actual patterns of variation in the number of described species and the expected numbers of described species predicted by the sampling model reveals that more species are known from the Cenozoic than would be predicted from the abundance of Cenozoic sediments or from the amount of paleontological interest in the Cenozoic. This might have resulted from the Cenozoic sediments remaining relatively free of diagenetic effects which might have destroyed the fossils entombed in the sediments.

scholarly journals Power laws from the bird species abundance distribution

2021 ◽  
Author(s):  
Sergio Da Silva ◽  
Raul Matsushita
Keyword(s):  
Extinction Risk ◽  
Species Abundance ◽  
Bird Species ◽  
Power Laws ◽  
Large Species ◽  
Species Abundance Distribution ◽  
Power Law Distribution ◽  
Abundance Distribution ◽  
The Hierarchical Structure ◽  
Log Normal

A recent study found that bird species with fewer individuals are abundant, but large species are rare. We show that this new data strongly suggests a power-law distribution rather than the most accepted log-normal. Moreover, we discuss extinction risk across the bird phylogeny and future conservation efforts by profiting from the hierarchical structure revealed by the new data.

Post-fire succession during the long-term absence of fire in coastal heathland and a test of the chronosequence survey method

2015 ◽  
Vol 63 (7) ◽  
pp. 572 ◽  
Author(s):  
Marc Freestone ◽  
Timothy J. Wills ◽  
Jennifer Read
Keyword(s):  
Species Richness ◽  
Fire History ◽  
Species Abundance ◽  
Tree Cover ◽  
Survey Method ◽  
Total Species Richness ◽  
Historical Factor ◽  
Declining Species ◽  
Total Species

Post-fire vegetation succession in long-unburnt heathland in south-east Australia is not well understood. In the present study we investigated temporal change in vegetation along a 37-year post-fire chronosequence in coastal heathland in the Gippsland Lakes Coastal Park, Victoria, Australia. Fourteen sites were surveyed for vegetation characteristics approximately 10 years after an initial chronosequence survey, enabling an extension of the chronosequence to cover a longer fire-free interval as well as testing predictions of declining species richness and diversity from the initial chronosequence study. Total species richness, mean species richness, mean diversity and mean evenness declined with time since fire across the 14 sites. However, only diversity (H) and evenness (E) decreased within sites as predicted in the original chronosequence study. No decrease in species richness within sites was observed. The chronosequence correctly predicted changes in species abundance but not the number of species present. Tree cover also increased, suggesting that the heathland was becoming a woodland in the long-term absence of fire. Fire history, which is an uncontrolled historical factor, provides the most likely explanation for why species richness did not decrease as predicted by the initial chronosequence. This study advocates caution in using the chronosequence method to predict species richness during post-fire succession.

Diversity, abundance and distribution of grasshopper species (Orthoptera: Acrididea) in three different types of vegetation with different levels of anthropogenic disturbances in the Littoral Region of Cameroon

2020 ◽  
Vol 14 (1) ◽  
pp. 16-33 ◽  
Author(s):  
YETCHOM-FONDJO JEANNE AGRIPPINE ◽  
KEKEUNOU - SÉVILOR ◽  
KENNE - MARTIN ◽  
MISSOUP ALAIN DIDIER ◽  
SHENG-QUAN XU
Keyword(s):  
Species Richness ◽  
Species Abundance ◽  
Anthropogenic Disturbances ◽  
Species Abundance Distribution ◽  
Abundance Distribution ◽  
Distribution Models ◽  
Eyprepocnemis Plorans ◽  
Grasshopper Species ◽  
Littoral Region ◽  
Abundance And Distribution

Grasshoppers have been identified as excellent monitors of landscape use. Despite their importance, their composition and distribution in the highly disturbed Littoral Cameroon is still unknown. The aim of this study was to determine the effect of human activities on diversity, abundance and distribution of grasshopper species in the Littoral region of Cameron. We investigated three types of vegetation differing remarkably on the level of anthropogenic impact (farmlands, fallows and forests), using sweep netting. The eight non-parametric estimators for specific richness, abundance, α and β diversity indices and species abundance distribution models, were used to compare the structure of communities among vegetation. Overall, 38 species belonging to three families and ten subfamilies were recorded. The Acrididae was the most diverse family. The species richness, abundance and diversity were higher in farmlands than in fallows and in forests. Five species occurred exclusively in farmlands, one in fallows and four in forests. Eyprepocnemis plorans, Coryphosima stenoptera, Serpusia opacula were overall the most abundant species respectively in cultivated farms, fallows and forests. Species abundance distribution fitted the Motomura model in all sites. Serpusia opacula is considered as a useful indicator since its presence and abundance significantly depend on the rate of forest naturalness. The farmlands were characterized by short vegetation while the fallows and forests were dominated by tall grasses and tall trees respectively. Anthropogenic disturbances promote the species richness, diversity and abundance of open meadow species, while it is detrimental to forest species which are sensitive, specialized and have limited dispersal abilities. Key words: Grasshopper, diversity, abundance, distribution, bioindicator

Combining counts and incidence data: an efficient approach for estimating the log-normal species abundance distribution and diversity indices

Oecologia ◽  
2012 ◽  
Vol 170 (2) ◽  
pp. 477-488 ◽  
Author(s):  
Edwige Bellier ◽  
Vidar Grøtan ◽  
Steinar Engen ◽  
Ann Kristin Schartau ◽  
Ola H. Diserud ◽  
...  
Keyword(s):  
Species Abundance ◽  
Diversity Indices ◽  
Species Abundance Distribution ◽  
Abundance Distribution ◽  
Efficient Approach ◽  
Incidence Data ◽  
Log Normal

Rarefaction and rarefiction—the use and abuse of a method in paleoecology

Paleobiology ◽  
1979 ◽  
Vol 5 (4) ◽  
pp. 423-434 ◽  
Author(s):  
John C. Tipper
Keyword(s):  
Species Richness ◽  
Species Abundance ◽  
Species Abundance Distribution ◽  
Abundance Distribution ◽  
Rarefaction Curve ◽  
Rarefaction Curves ◽  
Species Abundance Distributions

Rarefaction is a method for comparing community diversities that has consistently been abused by paleoecologists: here its assumptions are clarified and advice given on its application. Rarefaction should be restricted to comparison of collections from communities that are taxonomically similar and from similar habitats: the collections should have been obtained by using standardised procedures. The rarefaction curve is a graph of the estimated species richness of sub-samples drawn from a collection, plotted against the size of sub-sample: it is a deterministic transform of the collection's species-abundance distribution. Although rarefaction curves can be compared statistically, it may be more efficient to compare the species-abundance distributions directly. Both types of comparison are discussed in detail.

scholarly journals MoB (Measurement of Biodiversity): a method to separate the scale-dependent effects of species abundance distribution, density, and aggregation on diversity change

2018 ◽  
Author(s):  
Daniel J. McGlinn ◽  
Xiao Xiao ◽  
Felix May ◽  
Nicholas J. Gotelli ◽  
Thore Engel ◽  
...  
Keyword(s):  
Species Richness ◽  
Spatial Scale ◽  
Species Abundance ◽  
Simulated Data ◽  
Spatial Arrangement ◽  
Plant Species Richness ◽  
List Type ◽  
Species Abundance Distribution ◽  
Abundance Distribution ◽  
Rarefaction Curves

AbstractLittle consensus has emerged regarding how proximate and ultimate drivers such as productivity, disturbance, and temperature may affect species richness and other aspects of biodiversity. Part of the confusion is that most studies examine species richness at a single spatial scale and ignore how the underlying components of species richness can vary with spatial scale.We provide an approach for the measurement of biodiversity (MoB) that decomposes changes in species rarefaction curves into proximate components attributed to: 1) the species abundance distribution, 2) density of individuals, and 3) the spatial arrangement of individuals. We decompose species richness by comparing spatial and nonspatial sample- and individual-based species rarefaction curves that differentially capture the influence of these components to estimate the relative importance of each in driving patterns of species richness change.We tested the validity of our method on simulated data, and we demonstrate it on empirical data on plant species richness in invaded and uninvaded woodlands. We integrated these methods into a new R package (mobr).The metrics that mobr provides will allow ecologists to move beyond comparisons of species richness in response to ecological drivers at a single spatial scale towards a dissection of the proximate components that determine species richness across scales.

Sign in / Sign up

Export Citation Format

Share Document