scholarly journals Numerical Extrapolation of the Species Abundance Distribution Unveils the True Species Richness and the Hierarchical Structuring of a Partially Sampled Marine Gastropod Community in the Andaman Islands (India)

2018 ◽  
Vol 6 (4) ◽  
pp. 1-23
Author(s):  
Jean Béguinot
Keyword(s):  
Species Richness ◽  
Species Abundance ◽  
Andaman Islands ◽  
Species Abundance Distribution ◽  
Abundance Distribution ◽  
Marine Gastropod ◽  
Hierarchical Structuring

scholarly journals Disentangling and Quantifying the Functional Determinants of Species Abundance Unevenness in Ecological Communities

2019 ◽  
pp. 1-14
Author(s):  
Jean Béguinot
Keyword(s):  
Species Richness ◽  
Functional Organization ◽  
Species Abundance ◽  
Practical Implementation ◽  
Ecological Communities ◽  
Species Abundance Distribution ◽  
Abundance Distribution ◽  
Hierarchical Structuring ◽  
The Difference ◽  
The One

Species richness and species abundance unevenness are two major synthetic descriptors of the internal organization within ecological communities. Yet, while the former is a simple concept in essence, the unevenness of species abundance distribution is less so, being partly linked (negatively) to species richness as a general trend while, yet, more or less deviating from this average trend according to idiosyncratic specificities of each community (a bit similar to the size among individuals of a same species, which depend on age but more or less deviates due to inter-individual differences in growth rate which singularizes each individual). I argue that for abundance unevenness it is therefore relevant to consider and quantify separately these two aspects – the overall trend on the one hand and the idiosyncratic deviation from this trend on the other hand. In particular, comparing abundance unevenness levels between communities differing in species richness requires considering separately what has to be directly assigned to the difference in species richness and what can be relevantly attributed to some genuine, idiosyncratic difference in the hierarchical structuring of abundances between the compared communities. The appropriate formalism arising from this approach is detailed for practical implementation, thereby allowing for a deeper understanding of the ins and outs of the functional organization within ecological communities.

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.

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.

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

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.

scholarly journals Disentangling Environmental Effects on the Tree Species Abundance Distribution and Richness in a Subtropical Forest

2021 ◽  
Vol 12 ◽  
Author(s):  
Guang Feng ◽  
Jihong Huang ◽  
Yue Xu ◽  
Junqing Li ◽  
Runguo Zang
Keyword(s):  
Species Richness ◽  
Species Diversity ◽  
Soil Nutrients ◽  
Abiotic Factors ◽  
Species Abundance ◽  
Species Abundance Distribution ◽  
Abundance Distribution ◽  
Negative Effects ◽  
Diversity Patterns ◽  
Positive Effects

As a transitional vegetation type between evergreen broadleaved forest and deciduous broadleaved forest, evergreen-deciduous broadleaved mixed forest is composed of diverse plant species. This distinctive forest is generally distributed in mountainous areas with complex landforms and heterogeneous microenvironments. However, little is known about the roles of environmental conditions in driving the species diversity patterns of this forest. Here, based on a 15-ha plot in central China, we aimed to understand how and to what extent topographical characteristics and soil nutrients regulate the number and relative abundance of tree species in this forest. We measured environmental factors (terrain convexity, slope, soil total nitrogen, and phosphorus concentrations) and species diversity (species abundance distribution and species richness) in 20 m × 20 m subplots. Species abundance distribution was characterized by skewness, Berger–Parker index, and the proportion of singletons. The generalized additive model was used to examine the variations in diversity patterns caused by environmental factors. The structural equation model was used to assess whether and how topographical characteristics regulate species diversity via soil nutrients. We found that soil nutrients had significant negative effects on species richness and positive effects on all metrics of species abundance distribution. Convexity had significant positive effects on species richness and negative effects on all metrics of species abundance distribution, but these effects were mostly mediated by soil nutrients. Slope had significant negative effects on skewness and the Berger–Parker index, and these effects were almost independent of soil nutrients. Soil nutrients and topographical characteristics together accounted for 9.5–17.1% of variations in diversity patterns and, respectively, accounted for 8.9–13.9% and 3.3–10.7% of the variations. We concluded that soil nutrients were more important than topographical factors in regulating species diversity. Increased soil nutrient concentration led to decreased taxonomic diversity and increased species dominance and rarity. Convexity could be a better proxy for soil nutrients than slope. Moreover, these abiotic factors played limited roles in regulating diversity patterns, and it is possible that the observed patterns are also driven by some biotic and abiotic factors not considered here.

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