scholarly journals Many More Consumers Not Always Induce Stronger Competition: Weaker Interspecific Competition Despite Higher Species Richness in Secondary Feeding Guild, as Compared to Primary

Author(s):  
Jean Béguinot

The species functional structuration (specifically in terms of species richness and average intensity of interspecific competition) is widely varying among species communities and this point is now very well documented in literature. But, what about the species functional structuration within the different feeding guilds that coexist in a same local community – in particular the primary and the secondary feeding guilds? Are there significant differences – or not – between them in this respect? This rather fundamental issue does not seem having been addressed yet, at least using appropriate investigative tools. However, a series of recently published case studies, precisely implementing such an adequate investigative approach, now deserves full consideration in this regard and makes the subject of the present review. Substantially, it results from this preliminary survey of the question that marked differences in the patterns of species functional structuration clearly singularize the secondary from the primary feeding guilds, within a same local community. More precisely, a consistent trend seems to arise, highlighting both: (i) a markedly greater species richness and, yet somewhat unexpectedly, (ii) a significantly reduced intensity in interspecific competition within secondary feeding guild as compared to primary. The point is discussed and interpreted as being the consequence of the fact that secondary feeders (typically carnivores) have obviously evolve quite more diversified feeding behaviors than did the primary feeders (typically herbivores).

Author(s):  
Jean Béguinot

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.


Diversity ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 387
Author(s):  
Beanélri B. Janecke

Catenas are undulating hillslopes on a granite geology characterised by different soil types that create an environmental gradient from crest to bottom. The main aim was to determine mammal species (>mongoose) present on one catenal slope and its waterholes and group them by feeding guild and body size. Species richness was highest at waterholes (21 species), followed by midslope (19) and sodic patch (16) on the catena. Small differences observed in species presence between zones and waterholes and between survey periods were not significant (p = 0.5267 and p = 0.9139). In total, 33 species were observed with camera traps: 18 herbivore species, 10 carnivores, two insectivores and three omnivores. Eight small mammal species, two dwarf antelopes, 11 medium, six large and six mega-sized mammals were observed. Some species might not have been recorded because of drought, seasonal movement or because they travelled outside the view of cameras. Mammal presence is determined by food availability and accessibility, space, competition, distance to water, habitat preferences, predators, body size, social behaviour, bound to territories, etc. The variety in body size and feeding guilds possibly indicates a functioning catenal ecosystem. This knowledge can be beneficial in monitoring and conservation of species in the park.


Author(s):  
Jean Béguinot

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.


Author(s):  
Emilia Grzędzicka ◽  
Jiří Reif

AbstractPlant invasions alter bird community composition worldwide, but the underlying mechanisms still require exploration. The investigation of feeding guild structure of bird communities can be informative in respect to the potential impact of invasion features on the availability of food for birds. For this purpose, we focused on determining the influence of the invasive Sosnowsky’s Hogweed Heracleum sosnowskyi on the abundance of birds from various feeding guilds. In spring and summer 2019, birds were counted three times on 52 pairs of sites (control + Heracleum) in southern Poland, at various stages of Sosnowsky’s Hogweed development (i.e. sprouting, full growth and flowering, all corresponding to respective bird counts). We have shown that the presence of invader negatively affected the abundance of birds from all feeding guilds. However, a closer examination of the invaded sites uncovered that responses of particular guilds differed in respect to development stages expressed by a set of characteristics of the invader. Ground and herb insectivores were more common on plots with a higher number of the invader, while the abundance of bush and tree insectivores was negatively correlated with hogweeds’ height. Granivores were not affected by the invader’s features, while the abundance of omnivores was negatively related to the number of flowering hogweeds. Besides showing the general negative impact of the invader on different feeding guilds, our research has shown that certain aspects of Sosnowsky’s Hogweed invasion may support or depress occurrence of different birds on invaded plots. Knowledge of these aspects may facilitate our capacity for coping with challenges the invasive plants put in front of bird conservationists.


2012 ◽  
Vol 33 (2) ◽  
pp. 181-197 ◽  
Author(s):  
Krzysztof Pabis ◽  
Jacek Siciński

Is polychaete diversity in the deep sublittoral of an Antarctic fiord related to habitat complexity?Seventy-six species of Polychaeta were found in 19 quantitative samples collected in the deep sublittoral (200-500 m) of Admiralty Bay (South Shetlands). Three assemblages were distinguished by similarity analysis (clustering, nMDS). The soft bottom in depths from 200 to 300m was strongly dominated byMaldane sarsi antarcticaand had very low species richness and diversity. The second assemblage was distinguished in the areas of the sea floor in the same depth range but with aggregations of Ascidiacea and Bryozoa. It was again characterized by high abundance ofMaldane sarsi antarctica, but showed significantly higher species richness and diversity. Diversity of polychaete feeding guilds was also high in these areas. This pattern was probably associated with an increased habitat complexity due to the presence of dense aggregations of large suspension feeders. High species richness and diversity was also noted in the third assemblage, associated with the deepest sublittoral (400-500 m) of Admiralty Bay. This is the area characterized by very stable environmental conditions, where the assemblage was dominated byTharyx cincinnatus, Sternaspissp.,Maldane sarsi antarctica, andAsychis amphiglypta.


Author(s):  
Вячеслав Иванович Моисеев

В статье даётся краткий очерк антиномической природы биоэтического дискурса и возможностей его геометрической визуализации. Рассматриваются два варианта визуализации. Первый связан с представлением той или иной ситуации как системы полярностей, которая в свою очередь моделируется в рамках векторной модели. В простейшем случае тезис и антитезис рассматриваются как два перпендикулярных вектора, а синтез – как их векторная сумма. В этом случае можно ввести и более количественную оценку «меры многомерности» полярной системы – как величины проекции её векторного представления на суммарный вектор. С использованием этих конструкций разбирается один пример из биоэтики, связанный со столкновением принципов милосердия и правдивости (проблема «лжи во спасение»). Деяние (действие или бездействие) интерпретируется как своеобразный оператор на событиях, который переводит одни события в другие. Предполагается, что субъект в своих деяниях рассматривает различные возможности и выбирает те из них, которые максимизируют ту или иную ценностную меру субъекта, в данном случае – меру векторной проекции полярного вектора ситуации на суммарный вектор – вектор синтеза базисных полярностей. Второй вариант визуализации связан с понятием антиномий в биоэтике – таких противоречий, которые не являются формально-логическими ошибками. В отличие от последних, в антиномиях как тезис, так и антитезис имеют свой момент оправдания в рамках тех или иных условий. Используется также понятие «антинома» – логического субъекта антиномии, который предицируется тезисом и антитезисом антиномии. Редукции антиномии соответствуют двум крайним аспектам антинома, которые называются его «редуктами» – по аналогии с редукцией волновой функции в квантовой механике. Приводятся различные примеры антиномов: биоэты, глоболоки, холомеры. В биоэтах один редукт выражает в большей мере биологические (биоредукт), второй – этические (эторедукт) определения антинома. В глоболоках выделяются глобальный (глоборедукт) и локальный (локоредукт) виды редуктов: первый выражает более глобальные (универсальные) этические определения, второй – более локальные, связанные с ценностями и нормами того или иного сообщества. Наконец, холомеры – вид антиномов, где антиномически соединяются определения целого (холоредукт) и части (мероредукт). Даётся их интерпретация как многомерных ментальных объектов в некотором обобщённом пространстве, так что крайние их аспекты (редукции антиномии) можно представить как проекции более многомерного состояния. В заключении делается предположение о связи биоэтических проблем с идеей ментальной многомерности, что составляет основу возможной визуализации как интерпретации ментальной многомерности на векторном её представлении. The article provides a brief outline of the antinomic nature of bioethical discourse and the possibilities of its geometric visualization. Two visualization options are considered. The first is associated with the representation of a particular situation as a system of polarities, which in turn is modeled in the framework of a vector model. In the simplest case, the thesis and the antithesis are considered as two orthogonal vectors P1 and P2, and the synthesis is considered as their vector sum S = P1+P2. In this case, we can also introduce a more quantitative estimate of the “measure of multidimensionality” M(P) of the polar system – as the magnitude of the projection of its vector representation P on the sum vector S, i.e. M(P) = (P,es), where es = S/|S| is the unit vector of the vector S, and (P,es) is the scalar product of the vectors P and es. Using these constructs, the author analyzes one example from bioethics related to the clash of the principles of mercy and truthfulness (the problem of “lying for salvation”). An act (action or omission) is interpreted as a kind of an operator on events that transforms some events into others. It is assumed that the subject considers various possibilities in their actions and chooses those that maximize a particular value measure of the subject, in our case, the measure M(P) of the vector projection of the polar vector P of the situation on the sum vector S – the vector of synthesis of basic polarities. The second version of visualization is related to the concept of antinomies – such contradictions that are not formal logical errors – in bioethics. In contrast to errors, in antinomies, both the thesis and the antithesis have their moment of justification within the framework of certain conditions. The concept “antinome” is also used; it is the logical subject of antinomy, which is predicated by the thesis and the antithesis of antinomy. Antinomy reductions correspond to two extreme aspects of the antinome, which are called its “reducts” – by analogy with the reduction of the wave function in quantum mechanics. Various examples of antinomes are given: bioets, globolocs, and holomers. In bioets, one reduct expresses the biological (bioreduct) definition of the antinome, another the ethical (ethoreduct) one. In globolocs, global (globoreduct) and local (locoreduct) types of reducts are distinguished: the former expresses more global (universal) ethical definitions, the latter more local ones, related to the values and norms of a particular local community. Finally, holomers are a kind of antinomes in which the definitions of the whole (holoreduct) and the part (meroreduct) are antinomically connected. They are interpreted as multidimensional mental objects in some generalized space, so that their extreme aspects (antinomy reductions) can be represented as generalized projections of a more multidimensional state within certain constricted conditions (reduction intervals). In this case, it is possible to geometrically visualize such states as, for example, three-dimensional objects in space, through which antinomes can be modeled, and their reducts as two-dimensional projections of a three-dimensional body on certain projection planes (intervals of reducts). In this case, one of the central tasks of bioethics is to determine the boundaries of the demarcation of some intervals from others. For example, in solving the problem of abortion and the status of the human embryo, such a demarcation is expressed in the search for a time point that would separate the phase of a more biological definition (bioreduct) of the embryo from its more ethical state (ethoreduct). In conclusion, the author suggests that bioethical problems are connected with the idea of mental multidimensionality, which forms the basis of a possible visualization as an interpretation of mental multidimensionality in its vector representation.


2018 ◽  
Vol 8 (2) ◽  
pp. 259-274
Author(s):  
Ichsan Habibi

Positive contributions and trends in the tourism sector on Bangka Island, especially in the Matras Tourism Village, need to receive appreciation and support from all stakeholders through the management of environmentally friendly and sustainable tourist objects / attractions. To realize this mission, it is necessary to do ecological propaganda (religious values ​​originating from the Qur'an and Hadith) that are in accordance with the sociocultural characteristics of society. This issue is the subject of discussion in this study, especially regarding the values ​​of ecological preaching implemented in the development program of the Mattress Tourism Village. For this reason, a descriptive-qualitative study was conducted by collecting purposive-snowball data from the sample. Furthermore, the collected data was analyzed descriptively-qualitatively so that the values ​​of ecological preaching that had been implemented were identified and the form and process of implementation by the Matras Tourism Village community. The findings show that there are five types of ecological preaching values ​​that have been implemented, namely al-Is (justice), al-Tawazun (balance), al-Intifa 'wa laa al-Fasad (taking benefits without damage), ar-Riayah wa laa al -Israf (nurturing without exaggeration), and al-Tahdits wa al-Istikhlaf (renewal). Unfortunately, the value of al-Tahdits wa al-Istikhlaf is still not optimal due to the quality of science and technology. However, the local community has become more aware and intelligent about the importance of ecological preaching values ​​in the development of Mattress Tourism Village. In the future, besides needing to intensify and harmonize the role of ulama and Umara, it must also be carried out to increase the capacity of religious institutions, knowledge and appropriate technology for program implementers, and to involve community participation in planning, implementing and evaluating the Matras Tourism Village development program.


Zoodiversity ◽  
2021 ◽  
Vol 55 (6) ◽  
pp. 451-458
Author(s):  
G. Kopij

The line transect method has been employed to assess species diversity, population densities and community structure of birds breeding in a mosaic of Kalahari Woodland and farmland, NE Namibia. The transect, 4.5 km long, was surveyed in 2014 and 2015. The total annual rainfall in 2014 was much higher than in 2015 (427 mm vs. 262 mm). In total, 40 breeding species in 2014, and 46 in 2015 were recorded. Six species were dominant in 2014 (Cape Turtle Dove, Laughing Dove, Emerald-spotted Dove, Blue Waxbill, and White-browed Scrub Robin) and only three species in 2015 (Cape Turtle Dove and Blue Waxbill and Yellow-fronted Canary). Although the cumulative dominance in 2014 almost doubled that in 2015, the Community Index in both years was almost identical. Also diversity indices and evenness index were very similar in both years compared. Granivorous birds were the most numerous feeding guild. Their contribution was similar in 2014 and 2015 (46.7 % vs. 43.4 %). Two other feeding guilds, insectivores and frugivores, comprised together more than 50 % in both years. The number of bird species and species diversity were not influenced by the differential rainfall. However, contrary to expectations, population densities of most bird species (at least the more numerous ones) were higher in the year with lower than in the year with higher rainfall. The number of species and species diversity was similar in the farmland and in neighbouring Kalahari Woodland in a pristine stage. However, population densities of most species were lower in the farmland than in the pristine woodland.


2013 ◽  
Vol 13 (2) ◽  
pp. 4989-5038
Author(s):  
E. Solazzo ◽  
A. Riccio ◽  
I. Kioutsioukis ◽  
S. Galmarini

Abstract. We explicitly address the fundamental issue of member diversity in multi-model ensembles. To date no attempts in this direction are documented within the air quality (AQ) community, although the extensive use of ensembles in this field. Common biases and redundancy are the two issues directly deriving from lack of independence, undermining the significance of a multi-model ensemble, and are the subject of this study. Shared biases among models will determine a biased ensemble, making therefore essential the errors of the ensemble members to be independent so that bias can cancel out. Redundancy derives from having too large a portion of common variance among the members of the ensemble, producing overconfidence in the predictions and underestimation of the uncertainty. The two issues of common biases and redundancy are analysed in detail using the AQMEII ensemble of AQ model results for four air pollutants in two European regions. We show that models share large portions of bias and variance, extending well beyond those induced by common inputs. We make use of several techniques to further show that subsets of models can explain the same amount of variance as the full ensemble with the advantage of being poorly correlated. Selecting the members for generating skilful, non-redundant ensembles from such subsets proved, however, non-trivial. We propose and discuss various methods of member selection and rate the ensemble performance they produce. In most cases, the full ensemble is outscored by the reduced ones. We conclude that, although independence of outputs may not always guarantee enhancement of scores (but this depends upon the skill being investigated) we discourage selecting the members of the ensemble simply on the basis of scores, that is, independence and skills need to be considered disjointly.


Author(s):  
Gustavo Mattos ◽  
Ricardo S. Cardoso ◽  
André Souza Dos Santos

Several studies have been conducted to explain patterns of the abundance, richness and diversity of sandy-beach macrofauna; however, such analyses have ignored the overall functional structure of macrofauna communities. Few studies have examined polychaete feeding guilds on sandy beach environments. To examine the effects of environmental factors on polychaete feeding guilds on sandy beaches, 12 sandy beaches from five islands in Sepetiba Bay were sampled. A total of 24 polychaete morphospecies, grouped among 21 families, were identified in these sandy beaches. The polychaete species were classified into 10 feeding guilds, and the SDT guild (suspended-deposit feeders, discretely motile, with tentacles) was the most abundant feeding guild, with 34.2% of total number of organisms. The highest trophic importance index and index of trophic diversity values were recorded on the sheltered beaches. A canonical correspondence analysis showed that the exposure rate, beach length, and grain size of the beach sediment significantly affected the polychaete feeding guild distribution and abundance. We can conclude that sheltered beaches have a higher diversity of feeding guilds than exposed beaches and that the biological descriptors of the feeding guilds are directly associated with the grain size of the sediment.


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