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 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.

Seasonal Occurrence of Adult Carabid Beetles (Coleoptera: Carabidae) in West-Central Illinois

2020 ◽  
Vol 55 (3) ◽  
pp. 329-343
Author(s):  
Kenneth W. McCravy ◽  
Jason E. Willand
Keyword(s):  
Species Richness ◽  
Species Composition ◽  
Tallgrass Prairie ◽  
Activity Patterns ◽  
Species Abundance ◽  
Abundant Species ◽  
Early Summer ◽  
Carabid Beetles ◽  
West Central ◽  
Central Illinois

Abstract The Carabidae is a diverse family of beetles with many species of interest in conservation and biological control. Carabid beetle adult seasonal activity patterns were studied in a west-central Illinois forest/reconstructed tallgrass prairie matrix over a 2-yr period using pitfall traps. We found a threefold or greater difference in carabid abundance between years. Despite lower abundance, a second year of sampling yielded seven previously undetected species. Abundance and species richness were greatest in May–July and lower in August–October. Relative abundance and species richness were consistent among months between years. Shannon diversity and effective number of species were lowest in June and July. Cyclotrachelus sodalis (LeConte) and Chlaenius platyderus Chaudoir were the two most abundant species, comprising 54.3% of total captures. These species were most abundant in July and June, respectively. Most species showed greatest abundance in spring or early summer, and declined thereafter. Collections of several species were suggestive of bimodal seasonal patterns. Carabid species composition differed significantly among months, but not between years. Our results document seasonal variation in carabid abundance and species composition, and show that sampling throughout the growing season, and multiple sampling years, provide substantial benefits for assessments of carabid diversity in this region.

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 Assemblages of drosophilids (Diptera, Drosophilidae) in mangrove forests: community ecology and species diversity

2010 ◽  
Vol 100 (2) ◽  
pp. 133-140 ◽  
Author(s):  
Hermes J. Schmitz ◽  
Paulo R. P. Hofmann ◽  
Vera L. S. Valente
Keyword(s):  
Species Richness ◽  
Species Composition ◽  
Species Abundance ◽  
Mangrove Forests ◽  
Species Abundance Distribution ◽  
Conservation Areas ◽  
Apparent Lack ◽  
Breeding Sites ◽  
Richness Estimators ◽  
Harsh Conditions

Brazilian fauna of drosophilids has been researched in various ecosystems, but those in mangrove forests remain overlooked in Brazil and elsewhere. The present study attempts to characterise the assemblages of drosophilids of this environment, based on 28 collections taken in three mangrove areas in Santa Catarina Island, southern Brazil. The three mangroves surveyed were different in their surroundings, which varied from highly urbanised areas to conservation areas with natural vegetation. Overall, 69 species were collected, and no remarkable difference was detected in species composition and abundances or in the richness, evenness and heterogeneity between sites. The species abundance distribution observed fitted to a theoretical lognormal distribution in the three mangroves. The species richness scored and the performance of the species richness estimators showed an unexpectedly high diversity, considering the very low floristic diversity and the harsh conditions of the environment. Regarding species composition and abundances, the drosophilid mangrove assemblages were shown to be more similar to those found in open environments, with a marked dominance of exotic species. Finally, considering the apparent lack of feeding and breeding sites, we suggest that mangrove forests are acting as sink habitats for the drosophilids populations.

Influence of the environmental heterogeneity of breeding ponds on anuran assemblages from southeastern Brazil

2009 ◽  
Vol 87 (8) ◽  
pp. 699-707 ◽  
Author(s):  
T. S. Vasconcelos ◽  
T. G. Santos ◽  
D. C. Rossa-Feres ◽  
C.F.B Haddad
Keyword(s):  
Species Richness ◽  
Species Composition ◽  
Beta Diversity ◽  
Environmental Heterogeneity ◽  
Null Model ◽  
Distinct Species ◽  
Southeastern Brazil ◽  
Similar Species ◽  
Anuran Species ◽  
High Beta

We hypothesized that the environmental heterogeneity of breeding ponds influences the species composition and species richness of anuran assemblages from southeastern Brazil, because it provides humidity, shelter, and breeding microhabitats for anuran species, which can result in an increasing number of species in a given habitat. To begin, we tested whether the occurrence of anuran species in each breeding pond is different from a null model of random placement of species in those ponds. We then performed two tests to evaluate which of the five environmental descriptors of breeding ponds influence (1) the species composition and (2) species richness. Species composition of the 38 breeding ponds was correlated with number of edge types, number of plant types along the edges of the breeding ponds, and the hydroperiod. Neither the percentage of vegetation cover on the water’s surface nor the size of the breeding ponds were correlated with species composition. Only the number of edge types was correlated with species richness of breeding ponds. The correlation of three environmental descriptors with species composition and one environmental descriptor with species richness, as well as the high beta diversity among breeding ponds, suggest that the analyses of environmental heterogeneity on species composition was more informative than was the analysis for species richness, because breeding ponds with similar species richness can have distinct species composition among them (high beta diversity).

scholarly journals Variation in Leafhopper Species Abundance and Diversity among Elm Seedlings and Cultivars

HortScience ◽  
2005 ◽  
Vol 40 (5) ◽  
pp. 1389-1393 ◽  
Author(s):  
Jo-Ann Bentz ◽  
Alden M. Townsend
Keyword(s):  
Species Richness ◽  
Species Composition ◽  
Xylella Fastidiosa ◽  
Species Abundance ◽  
Growing Season ◽  
The Other ◽  
Species Similarity ◽  
Abundance And Diversity ◽  
Elm Yellows ◽  
Selection Of

A survey was conducted in the 2001 growing season to determine the leafhopper species composition, abundance, richness, diversity, and evenness among trees of three elm (Ulmus sp.) cultivars, two U.S. National Arboretum (USNA) seedling selections of U. szechuanica Fang, and two USNA seedling selections of U. bergmanniana Schneid. in a mixed stand. Yellow sticky traps were used to qualify and quantify the number of aerial leafhoppers from 1 May 2001 until 4 September 2001. A total of 4,523 individuals, belonging to 39 species within seven leafhopper subfamilies, were trapped. The weekly mean number of leafhoppers collected was significantly higher on traps from `Patriot', followed by `Frontier' and `Prospector', than on traps from the USNA seedling selections. Although the weekly mean species richness for `Prospector' was lower than the other two cultivars, the three cultivars had higher mean species richness than the USNA seedling selections of U. szechuanica and U. bergmanniana. Diversity among cultivars was higher than among the USNA seedling selections. Ulmus bergmanniana 68983 and U. szechuanica 68986 shared the highest percentage of species similarity, while `Frontier' and U. szechuanica 68991 were the most dissimilar. Of the species collected, Agallia quadripunctata, Empoasca fabae and Graphocephala versuta were the most abundant. The other species were mostly rare based on their low abundance. Scaphoideus luteolus, the only confirmed vector of elm yellows in North America, was found among the elm cultivars only. Yet, the Cicadellinae leafhoppers that are vectors of Xylella fastidiosa, the causal agent of bacterial leaf scorch, were found among both the cultivars and USNA seedling selections. Such data could allow for the screening and selection of elms resistant to economically important leafhoppers.

Geographic distribution, large-scale spatial structure and diversity of parasitoids of the seed-feeding beetleAcanthoscelides macrophthalmus

2016 ◽  
Vol 107 (3) ◽  
pp. 322-331 ◽  
Author(s):  
A. Wood ◽  
E.B. Haga ◽  
V.A. Costa ◽  
M.N. Rossi
Keyword(s):  
Species Richness ◽  
Spatial Structure ◽  
Species Composition ◽  
Geographic Distribution ◽  
Large Scale ◽  
Current Knowledge ◽  
Spatial Scales ◽  
Species Abundance ◽  
Geographic Area ◽  
Parasitoid Species

AbstractBruchine beetles are highly host-specific seed feeders during the larval stage. Although some specific parasitoid families have been recorded attacking bruchine beetles, most studies have been done at small spatial scales. Therefore, the current knowledge about the diversity and the geographic distribution of parasitoid species parasitizing bruchines is scarce, especially at a wide geographic area that extends over large distances through a latitudinal cline (i.e. large-scale spatial structure). The present study determined the species richness and evenness of parasitoids attacking the bruchine beetleAcanthoscelides macrophthalmusfeeding onLeucaena leucocephalaseeds, examined their geographic distribution, and characterized the large-scale spatial structure in parasitoid species composition. A total of 1420 parasitoids (all Hymenoptera) belonging to four families, five subfamilies and eight species were collected (genera:Horismenus, Paracrias, Urosigalphus, Stenocorse, Chryseida, Eupelmus). Most parasitoid species showed wide spatial distribution, high evenness in species abundance and the species richness estimators were close to stabilization (approximately eight species). Overall, greater similarity was observed in the species composition of plant populations near to each other than those farther apart, revealing a large-scale spatial structure in parasitoid species composition.

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 17 Years Successional Enrichment Plantation of Tree Recruitment and Restoration in Tropical Forestland

2021 ◽  
Author(s):  
Bernard Eromosele Omomoh ◽  
Victor AJ Adekunle
Keyword(s):  
Species Richness ◽  
Species Diversity ◽  
Species Composition ◽  
Growth Form ◽  
Species Abundance ◽  
Forest Trees ◽  
Tree Species Composition ◽  
Significant Difference ◽  
Result Show ◽  
One Way Anova

Abstract BackgroundWe examine the recruitment drive of overstorey and undergrowth of tropical forested reserve by assessing the tree diversity, species composition, species richness, and growth form of the undergrowth on 17 years of post-disturbance. ResultThe result show an increase in the diversity and even distribution of the species of the overstorey, compared to the undergrowth. Conversely, the overstorey has a lower in species richness as compared to the level of undergrowth. One way ANOVA results shows that there is no significant difference (P = 0.341). However, undergrowth density (individual/ha) is found to be significantly (P = 0.000) higher than the overstorey trees.ConclusionsIt is evident that the forest trees and saplings are dissimilar in species abundance, which implies that sapling recruitment is a key determinant of the tree species composition of the forest. It is then concluded that the method adopted for restoration encouraged species diversity in this successional forest.

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