scholarly journals A New, Ecologically Self-Significant Metric of Species-Abundance Unevenness, Reliably Highlighting the Intensity of Interspecific Competition

2021 ◽  
pp. 48-71
Author(s):  
Jean Béguinot
Keyword(s):  
Species Richness ◽  
Interspecific Competition ◽  
Species Abundance ◽  
Point Of View ◽  
Distribution Model ◽  
Conventional Measure ◽  
Species Abundances ◽  
Stick Model ◽  
Descriptive Purpose ◽  
Intensity Of Competition

A wide series of commonly used metrics of abundance-evenness (or -unevenness) have been proposed to characterize synthetically the distributions of species-abundances, accounting for the hierarchic-like organization of species within natural communities. Among them, most – if not all–have been relevantly criticized on their serious limitations regarding both their “descriptive” and their “interpretative” capacities. From the descriptive point of view, many authors have already repeatedly emphasized the formal non-independenceof conventional (un-)evenness metrics with respect to species-richness, leading, in particular, to unacceptable bias when comparing communities differing by their species-richness, thus making these metrics unreliable descriptors in this respect. Now, as regards the capacity to provide relevant ecological interpretations, especially in terms of the intensity of competition among co-occurring species, the weakness of conventional (un-)evenness metrics is readily highlighted by the usual absence of any associated interpretation of this kind in the literature: the conventional (un-)evenness metrics beingrestricted to purely descriptive purpose only. Accordingly, a newly designed abundance-unevenness metric – the “standardized abundance-unevenness” index is proposed, positively addressing both kinds of limitations evoked above. By standardizing a conventional measure,U,of abundance-unevenness to the corresponding measure, U’, of the abundance-unevenness in the well-known “broken-stick” model, the resulting “standardized unevenness” index (Istr = U/U’) proves to be efficient against both themajor limitations pointed-out above:indeed,the new index does benefit by being both (i) formally independent from species-richness, thereby allowing reliable,unbiased comparisons of abundance unevenness between species-communities, whatever their difference in species-richness; (ii) able to relevantly quantify the mean intensity of interspecific-competition within community, in term of its direct outcomeuponthe degree of species-abundance unevenness. This double success being, of course, the direct consequences of the properties of the “broken-stick” distribution model, originally putforth in a well-known, yet insufficiently thoroughly exploited paper by the regretted Robert MacArthur.

scholarly journals Influence of Environmental Heterogeneity on the Species Composition, Species Richness and Species Abundances Unevenness in Reef-associated Conus Communities (Neogastropoda) from Papua New-Guinea

2019 ◽  
pp. 1-21
Author(s):  
Jean Béguinot
Keyword(s):  
Species Richness ◽  
Species Composition ◽  
Environmental Heterogeneity ◽  
Species Abundance ◽  
Jaccard Index ◽  
Point Of View ◽  
Fundamental Issue ◽  
Marine Communities ◽  
Surrounding Environment ◽  
Species Abundances

To what extent differences in species composition, species richness and species abundance unevenness between marine communities are attributable to heterogeneities of the surrounding environment and/or to inter-community distance is a fundamental issue to be addressed, in order to more deeply understand the functioning of marine ecosystems. A comparison between six reef-associated Conus communities, differing more or less in both their surrounding environment and their mutual geographical distance, offers a relevant opportunity to address these questions. As expected, environmental heterogeneities prove having a significant influence on the dissimilarity in species composition, whereas distance-decay in similarity reveals comparatively negligible, at least within the investigated range of distances, up to 60 km. Less expectedly, more homogeneous surrounding environments between communities tend, here, to increase the dissimilarity in species richness. At last, here, difference in species abundance unevenness between communities seems unrelated to either environmental heterogeneity or inter-community distance. From a methodological point of view, these results could not have been reliably established without the prior implementation of a least-biased procedure of numerical extrapolation applied to the available incomplete samplings. Also, the relevant assessment of dissimilarity in species composition required using a modified Jaccard index, rendered insensitive to bias-induced differences in communities species richness.

scholarly journals Progressive Recovery of a Marine Gastropod Community Following Atmospheric Nuclear Tests in French- Polynesia: A Socio-ecological Interpretation

2021 ◽  
pp. 77-110
Author(s):  
Jean Béguinot
Keyword(s):  
Species Richness ◽  
Interspecific Competition ◽  
Metastable Phase ◽  
Species Abundance ◽  
French Polynesia ◽  
Positive Contribution ◽  
Large Spatial Scale ◽  
Species Abundances ◽  
Nuclear Tests ◽  
Niche Diversification

Aims: The way species-richness is accommodated and how species-abundance distribution is organized in a hierarchic pattern is central to community ecology. Yet, the process by which species-richness and species-abundances are progressively accommodated can hardly be monitored, in practice, at a sufficiently large spatial scale. Fortunately, the progressive recovery of marine communities, after their complete destruction by atmospheric nuclear tests, yet offered unique opportunity to monitor the full process of accommodation of increasing species-richness and the associated, transient development of strong interspecific competition, all along the process of recovery. Methods: Taking full advantage of such monitoring yet requires, first, to relevantly overcome two important practical issues: 1) achieving reliable numerical extrapolations of the usually unavoidably incomplete samplings in order to accurately estimate both the true species-richness and the completed distribution of species-abundances, including the abundance of undetected species and 2) disentangling (i) the positive contribution of improved niche-diversification to species-richness and species-abundance evenness from (ii) the negative contribution of increasing interspecific-competition, all along the recovery progress. This, indeed, is a rather tricky challenge, yet relevantly solved by using the newly developed “standardized unevenness index”, conceptually based upon MacArthur approach to interspecific-contest at niche overlaps. Results: Applying both tools above to the monitored recovery of a reef-associated Gastropod community, entirely wiped-out previously by severe nuclear blasts, had allowed a deeper understanding of the dynamic interplay between species-recruitment, niche-diversification and interspecific-competition in the regeneration of the community. In particular, along the recovery process, a transient, metastable phase – involving severe interspecific-competition at niche-overlaps – precedes a gradual return to dynamic stability, with the virtual extinction of interspecific competition

scholarly journals Analyzing the Role of Increasing Water Pollution on Species-Richness, Interspecific-Competition and Abundance-Unevenness in Reef-Associated Fish Communities, off Jakarta Bay (Indonesia)

2021 ◽  
pp. 18-43
Author(s):  
Jean Béguinot
Keyword(s):  
Species Richness ◽  
Interspecific Competition ◽  
Fish Assemblages ◽  
Fish Communities ◽  
Empirical Support ◽  
Feeding Guilds ◽  
Common Trend ◽  
Total Species Richness ◽  
Species Abundances ◽  
The One

Not far from the exceptionally rich ‘Coral Triangle’ on the one hand but, on the other hand, exposed to strongly varying degree of anthropogenic environmental stresses, the reef-associated fish assemblages all along ‘Seribu Islands’ (off Jakarta Bay) are, thus, confronted to both positive and negative ecological influences. As such, these fish assemblages offer especially interesting opportunities to analyze these opposite ecological influences, at both the descriptive and the functional points of views. The least-biased numerical extrapolation of a series of recently reported – yet incomplete – samplings has allowed a sub-exhaustive account of both the estimated total species-richness and the completed distribution of species abundances – including the set of those rarer species which had remained unrecorded. Thanks to this numerically completed information, it became possible to tackle some important issues – which otherwise would have remained difficult to address properly. First, a remarkably good correlation was highlighted between the distance of fish assemblages to Jakarta Bay (distance considered as a reliable surrogate to the improvement of environmental conditions for fish assemblages) and a theoretically derived index characterizing the accommodation capacity of sites for fish assemblages. This good correlation suggests that this index offer a way to reliably accounts for the “environmental quality” of marine waters, as appreciated by fish communities. In quite another respect, comparing primary and secondary-feeding guilds, provides still further empirical support to a seemingly common trend according to which the guild of secondary-feeders features usually more species-rich, while exhibiting less interspecific competition intensity at niche overlaps, than does the primary-feeders guild.

Species abundance, accumulation and diversity data.

2021 ◽  
pp. 200-217
Author(s):  
Donald L. J. Quicke ◽  
Buntika A. Butcher ◽  
Rachel A. Kruft Welton
Keyword(s):  
Species Richness ◽  
Papua New Guinea ◽  
Niche Partitioning ◽  
Species Abundance ◽  
Diversity Indices ◽  
Estimation Methods ◽  
Summary Statistics ◽  
Accumulation Curves ◽  
Global Patterns ◽  
Stick Model

Abstract Ecologists in particular are often interested in the species richness and diversity of groups of organisms, ranging from studies of small ecosystems to global patterns. In most cases it is not possible to count every individual or to detect every species, and so they use a variety of estimation methods and summary statistics that will be briefly introduce in this chapter. This chapter covers estimating species abundance and species richness by looking at accumulation curves. Analyzing diversity using tests such as the Shannon and Simpson diversity indices are also discussed. Finally, patterns of niche partitioning using the broken stick model are created. An example is shown, using transect surveys of butterflies in Papua New Guinea.

Species abundance, accumulation and diversity data.

2021 ◽  
pp. 200-217
Author(s):  
Donald L. J. Quicke ◽  
Buntika A. Butcher ◽  
Rachel A. Kruft Welton
Keyword(s):  
Species Richness ◽  
Papua New Guinea ◽  
Niche Partitioning ◽  
Species Abundance ◽  
Diversity Indices ◽  
Estimation Methods ◽  
Summary Statistics ◽  
Accumulation Curves ◽  
Global Patterns ◽  
Stick Model

Abstract Ecologists in particular are often interested in the species richness and diversity of groups of organisms, ranging from studies of small ecosystems to global patterns. In most cases it is not possible to count every individual or to detect every species, and so they use a variety of estimation methods and summary statistics that will be briefly introduce in this chapter. This chapter covers estimating species abundance and species richness by looking at accumulation curves. Analyzing diversity using tests such as the Shannon and Simpson diversity indices are also discussed. Finally, patterns of niche partitioning using the broken stick model are created. An example is shown, using transect surveys of butterflies in Papua New Guinea.

scholarly journals Interspecific-Competition Strongly Constrains Species-Richness and Species-Abundance Evenness in a Tropical Marine Molluscan Community Inhabiting Caulerpa Beds, as Compared to Coral-Reefs

2021 ◽  
pp. 26-46
Author(s):  
Jean Béguinot
Keyword(s):  
Species Richness ◽  
Interspecific Competition ◽  
Local Community ◽  
Species Abundance ◽  
Positive Contribution ◽  
Habitat Features ◽  
Colonizing Species ◽  
The Stability ◽  
Taxonomic Groups ◽  
Niche Diversification

Increasing species-richness at the local scale (within species communities) is accommodated, first, by the diversification of the niches respectively associated to species. Yet, in case of excessive supply in colonizing species issued from the regional pool, the corresponding increase in the number of solicited niches may lead to some “niche-overcrowding” resulting in significant niche-overlaps. Then, second, strong interspecific competition for shared resource can arise, triggered by the density in individuals among those species co-occurring at niche-overlaps. Accordingly, the accommodation of species-richness within a local community involves a balance between (i) the positive contribution of improved niche-diversification and (ii) the negative consequence of induced interspecific-competition at increasing niche-overlaps once the number of colonizing species becomes too large. This balance can strongly differ according to the local ecological conditions, since the latter are expected to strongly influence the range of “overcrowding-free” diversification of niches. So that, concretely, each community requires a specific analysis, in order to disentangle and quantify the respective contributions of the niche-diversification and the intensity of interspecific-competition to this balance. And, in particular, their respective roles upon both the species-richness and the degree of unevenness of species abundance within community. Beyond its speculative interest, this deeper understanding of the process involved in the hierarchic-like organization of species within community also answers more practical concerns, in particular the stability of species-richness, partly dependent on the intensity of interspecific-competition. In this perspective, we quantify and compare how species-richness accommodation proceeds in two major taxonomic groups, Bivalves and Gastropods respectively, both belonging to a same molluscan community inhabiting Caulerpa beds, in the intertidal-zone of Siquijor Island (Philippines). Then, after having compared these two different taxonomic groups, the influence of environmental conditions on species-richness accommodation is addressed, showing that “Caulerpa-beds” habitat features far-less rewarding to Gastropods communities than can be the classical “coral-reef” habitat.

scholarly journals Native Species Abundance Buffers Non-Native Plant Invasibility following Intermediate Forest Management Disturbances

2019 ◽  
Vol 65 (3) ◽  
pp. 336-343 ◽  
Author(s):  
Donald P Chance ◽  
Johannah R McCollum ◽  
Garrett M Street ◽  
Bronson K Strickland ◽  
Marcus A Lashley
Keyword(s):  
Species Richness ◽  
Loblolly Pine ◽  
Native Species ◽  
Biotic Resistance ◽  
Species Abundance ◽  
Data Sets ◽  
Native Plant ◽  
Species Abundances ◽  
Intermediate Disturbances ◽  
Native Species Richness

Abstract The biotic resistance hypothesis (BRH) was proposed to explain why intermediate disturbances lead to greater resistance to non-native invasions proposing communities that are more diverse provide greater resistance. However, several empirical data sets have rejected the BRH because native and non-native species richness often have a positive relation. We tested the BRH in a mature loblolly pine (Pinus taeda) forest with a gradient of disturbance intensities including canopy reduction, canopy reduction + fire, and canopy reduction + herbicide and fire. We analyzed data from the study using a combination of Pearson’s correlation and beta regressions. Using species richness, we too would reject BRH because of a positive correlation in species richness between native and non-native plants. However, native species abundance was greatest, and non-native species abundance was lowest following intermediate disturbances. Further, native and non-native species abundances were negatively correlated in a quadratic relation across disturbance intensities, suggesting that native species abundance, rather than richness, may be the mechanism of resistance to non-native invasions. We propose that native species abundance regulates resistance to non-native invasions and that intermediate disturbances provide the greatest resistance because they promote the greatest native species abundance.

scholarly journals Patterns of Odonata Assemblages in Lotic and Lentic Systems in the Ankasa Conservation Area, Ghana

2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
Issah Seidu ◽  
Collins Ayine Nsor ◽  
Emmanuel Danquah ◽  
Paul Tehoda ◽  
Samuel K. Oppong
Keyword(s):  
Species Richness ◽  
Predictive Factors ◽  
Sampling Site ◽  
Species Abundance ◽  
Water Systems ◽  
Water Bodies ◽  
Freshwater Biodiversity ◽  
Sampling Protocol ◽  
Conservation Area ◽  
Stick Model

Our study examined Odonata assemblages distribution pattern and the predictive factors that accounted for this in the lotic and lentic water systems within the Ankasa Conservation Area (Ghana). A total of 23 sites with sampling protocol of 2 researchers per hour per sampling site were used to survey Odonata species over two seasons in the three water bodies (streams, rivers, and ponds). Broken stick model, individual-based rarefaction, and Renyi diversity ordering were employed to quantify community assemblages. Ordination technique was also used to determine the Odonata-environmental relationship. A total of 1403 individuals, belonging to 47 species (22 Zygoptera and 25 Anisoptera) in six families, were recorded. Species richness (Hc = 3.414, p = 0.169) and diversity (Hc = 1.661, p = 0.44) generally did not differ among the three water systems. However, from individual sites, ponds appeared mostly diverse (α-scale = 0.04, Renyi index (r) = 5.86 to α = 3.5, r = 3.12), in spite of their lowest species abundance and richness. At the suborder level, ponds equally exhibited the highest Anisoptera species richness (9.90 ± SE 0.640) compared with Zygopterans (0.80± SE 0.291). Overall, Anisopterans (K= 16.51, p= 0.00026) and Zygopterans richness (K= 16.39, p= 0.00023) differed significantly among the three subsystems, while Odonata composition also differed significantly among the various water bodies (ANOSIM: global R= 0.94, p<0.001). Flow rate, water temperature, channel width, and turbidity were the key predictive factors that influence the structure of Odonata species assemblages. The results highlight the need to improve the functional status of the lentic and lotic systems, with the ultimate goal of conserving diverse Odonata fauna and other sympatric freshwater biodiversity.

Dominance determines fish community biomass in a temperate seagrass ecosystem

2019 ◽  
Author(s):  
Aaron Matthius Eger ◽  
Rebecca J. Best ◽  
Julia Kathleen Baum
Keyword(s):  
Species Richness ◽  
Ecosystem Function ◽  
Fish Community ◽  
Prey Capture ◽  
Fish Communities ◽  
Functional Trait ◽  
Ecosystem Functions ◽  
Community Biomass ◽  
Ecosystem Valuation ◽  
Species Abundances

Biodiversity and ecosystem function are often correlated, but there are multiple hypotheses about the mechanisms underlying this relationship. Ecosystem functions such as primary or secondary production may be maximized by species richness, evenness in species abundances, or the presence or dominance of species with certain traits. Here, we combined surveys of natural fish communities (conducted in July and August, 2016) with morphological trait data to examine relationships between diversity and ecosystem function (quantified as fish community biomass) across 14 subtidal eelgrass meadows in the Northeast Pacific (54° N 130° W). We employed both taxonomic and functional trait measures of diversity to investigate if ecosystem function is driven by species diversity (complementarity hypothesis) or by the presence or dominance of species with particular trait values (selection or dominance hypotheses). After controlling for environmental variation, we found that fish community biomass is maximized when taxonomic richness and functional evenness is low, and in communities dominated by species with particular trait values – those associated with benthic habitats and prey capture. While previous work on fish communities has found that species richness is positively correlated with ecosystem function, our results instead highlight the capacity for regionally prevalent and locally dominant species to drive ecosystem function in moderately diverse communities. We discuss these alternate links between community composition and ecosystem function and consider their divergent implications for ecosystem valuation and conservation prioritization.

scholarly journals Complex community responses underpin biodiversity change following invasion

2021 ◽  
Author(s):  
Alessandra R. Kortz ◽  
Anne E. Magurran
Keyword(s):  
Invasive Species ◽  
Species Richness ◽  
Spatial Scales ◽  
Species Abundance ◽  
Ecological Systems ◽  
Multi Scale ◽  
Mechanistic Approach ◽  
Α Diversity ◽  
Biodiversity Change ◽  
Insight Into

AbstractHow do invasive species change native biodiversity? One reason why this long-standing question remains challenging to answer could be because the main focus of the invasion literature has been on shifts in species richness (a measure of α-diversity). As the underlying components of community structure—intraspecific aggregation, interspecific density and the species abundance distribution (SAD)—are potentially impacted in different ways during invasion, trends in species richness provide only limited insight into the mechanisms leading to biodiversity change. In addition, these impacts can be manifested in distinct ways at different spatial scales. Here we take advantage of the new Measurement of Biodiversity (MoB) framework to reanalyse data collected in an invasion front in the Brazilian Cerrado biodiversity hotspot. We show that, by using the MoB multi-scale approach, we are able to link reductions in species richness in invaded sites to restructuring in the SAD. This restructuring takes the form of lower evenness in sites invaded by pines relative to sites without pines. Shifts in aggregation also occur. There is a clear signature of spatial scale in biodiversity change linked to the presence of an invasive species. These results demonstrate how the MoB approach can play an important role in helping invasion ecologists, field biologists and conservation managers move towards a more mechanistic approach to detecting and interpreting changes in ecological systems following invasion.

Sign in / Sign up

Export Citation Format

Share Document