scholarly journals Environmental conditions promote local segregation, but functional distinctiveness allow aggregation of catfishes in the Amazonian estuary

2020 ◽  
Author(s):  
Bruno Soares ◽  
Naraiana Loureiro Benone ◽  
Ronaldo Borges Barthem ◽  
Alexandre Pires Marceniuk ◽  
Luciano Fogaça de Assis Montag
Keyword(s):  
Environmental Variables ◽  
Environmental Filtering ◽  
River Mouth ◽  
Niche Overlap ◽  
Limiting Similarity ◽  
Lower Salinity ◽  
Salinity Levels ◽  
Dry Seasons ◽  
Occurrence Patterns ◽  
Local Segregation

Cooccurrence patterns of species can appear through niche-related processes such as (i) environmental filtering matching specific sets of traits to a given environment, and (ii) limiting similarity selecting divergent functional traits to reduce niche overlap. Locally, both processes should act together to shape the distribution of species. We evaluated the importance of environmental variables and functional distinctiveness to the co-occurrence patterns of nine marine catfishes in the inner estuary of the Amazon River mouth. Sampling was carried out in the dry seasons of 1996 and 1997, and the rainy season of 1996 by nearly 120 standardized bottom trawls per expedition. We observed 13 significant pairs of segregated species and two pairs of aggregated species, which sum 41.7% of all combinations. Amphiarius phrygiatus and Sciades couma segregated from all the remaining marine catfishes by occupying shallower areas with lower salinity levels. Aggregated pairs were strongly associated with higher functional distinctiveness. We concluded that environmental filtering is the main force structuring the co-occurrence patterns by promoting spatial segregation, but functional distinctiveness allowed some species to aggregate.

scholarly journals Local Segregation of Realised Niches in Lizards

2020 ◽  
Vol 9 (12) ◽  
pp. 764
Author(s):  
Neftalí Sillero ◽  
Elena Argaña ◽  
Cátia Matos ◽  
Marc Franch ◽  
Antigoni Kaliontzopoulou ◽  
...  
Keyword(s):  
Environmental Variables ◽  
Ecological Niche ◽  
Species Coexistence ◽  
Niche Overlap ◽  
R Package ◽  
Abundant Species ◽  
Ecological Niche Models ◽  
Changes Over Time ◽  
Local Segregation ◽  
Niche Models

Species can occupy different realised niches when sharing the space with other congeneric species or when living in allopatry. Ecological niche models are powerful tools to analyse species niches and their changes over time and space. Analysing how species’ realised niches shift is paramount in ecology. Here, we examine the ecological realised niche of three species of wall lizards in six study areas: three areas where each species occurs alone; and three areas where they occur together in pairs. We compared the species’ realised niches and how they vary depending on species’ coexistence, by quantifying niche overlap between pairs of species or populations with the R package ecospat. For this, we considered three environmental variables (temperature, humidity, and wind speed) recorded at each lizard re-sighting location. Realised niches were very similar when comparing syntopic species occurring in the same study area. However, realised niches differed when comparing conspecific populations across areas. In each of the three areas of syntopy, the less abundant species shift its realised niche. Our study demonstrates that sympatry may shift species’ realised niche.

scholarly journals Co-occurrences of tropical trees in eastern South America: disentangling abiotic and biotic forces

Plant Ecology ◽  
2021 ◽  
Author(s):  
Emma-Liina Marjakangas ◽  
Otso Ovaskainen ◽  
Nerea Abrego ◽  
Vidar Grøtan ◽  
Alexandre A. de Oliveira ◽  
...  
Keyword(s):  
South America ◽  
Tree Species ◽  
Large Scale ◽  
Environmental Filtering ◽  
Limiting Similarity ◽  
Phylogenetic Relatedness ◽  
Biogeographical Regions ◽  
Dependent Processes ◽  
Occurrence Of Species

AbstractSpecies co-occurrences in local communities can arise independent or dependent on species’ niches. However, the role of niche-dependent processes has not been thoroughly deciphered when generalized to biogeographical scales, probably due to combined shortcomings of data and methodology. Here, we explored the influence of environmental filtering and limiting similarity, as well as biogeographical processes that relate to the assembly of species’ communities and co-occurrences. We modelled jointly the occurrences and co-occurrences of 1016 tropical tree species with abundance data from inventories of 574 localities in eastern South America. We estimated species co-occurrences as raw and residual associations with models that excluded and included the environmental effects on the species’ co-occurrences, respectively. Raw associations indicate co-occurrence of species, whereas residual associations indicate co-occurrence of species after accounting for shared responses to environment. Generally, the influence of environmental filtering exceeded that of limiting similarity in shaping species’ co-occurrences. The number of raw associations was generally higher than that of the residual associations due to the shared responses of tree species to the environmental covariates. Contrary to what was expected from assuming limiting similarity, phylogenetic relatedness or functional similarity did not limit tree co-occurrences. The proportions of positive and negative residual associations varied greatly across the study area, and we found a significant tendency of some biogeographical regions having higher proportions of negative associations between them, suggesting that large-scale biogeographical processes limit the establishment of trees and consequently their co-occurrences.

scholarly journals Environmental filtering and spillover explain multi-species edge responses across agricultural boundaries in a biosphere reserve

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
J. van Schalkwyk ◽  
J. S. Pryke ◽  
M. J. Samways ◽  
R. Gaigher
Keyword(s):  
Species Richness ◽  
Species Composition ◽  
Habitat Quality ◽  
Environmental Variables ◽  
Natural Habitat ◽  
Environmental Filtering ◽  
Biosphere Reserve ◽  
Natural Habitats ◽  
Habitat Specificity ◽  
Induced Changes

Abstract To ensure integrity of protected areas we need to understand how species respond to anthropogenic borders. We investigate, from a metacommunity perspective, the direct and indirect mechanisms by which transformed areas affect distribution patterns of ground-living arthropod assemblages inhabiting an extensive protected area adjacent to fruit orchards in an important biosphere reserve. Arthropods and environmental variables were sampled along transects perpendicular to natural-orchard edges. Influence of distance from orchard boundary, degree of impermeability of the boundary, orchard habitat quality (local scale land-use intensity), and edge-induced changes in local environmental variables on arthropod species richness and composition in non-crop habitats were assessed. Arthropod groups were assessed in terms of habitat fidelity: species associated with natural habitat (stenotopic species), those within crop habitat (cultural species), and those showing no preference for either habitat (ubiquitous species). Spillover resulted in higher cultural species richness near edges, but not higher overall species richness. Environmental filtering was important for stenotopic species composition, which was influenced by edge-induced changes in environmental variables. Ubiquitous species composition was determined by orchard impermeability. Increased orchard habitat quality was associated with higher cultural and ubiquitous species richness. The effects of orchards on assemblages in natural habitats can be variable, but predictable when using species habitat specificity in conjunction with a metacommunity framework. High intensity orchards may act as sink habitats, especially for species that readily disperse between crop and natural habitats. Here we recommend that local buffer strips are > 85 m wide, which will reduce the influence of cultural species spillover on sensitive natural ecosystems.

scholarly journals Nymphal feeding habits of two Anacroneuria species (Plecoptera, Perlidae) from Sierra Nevada de Santa Marta, Colombia

2018 ◽  
Vol 78 (1) ◽  
Author(s):  
Yesely M. Hurtado ◽  
Cesar E. Tamaris-Turizo ◽  
Manuel J. López Rodriguez ◽  
J. Manuel Tierno de Figueroa
Keyword(s):  
Sierra Nevada ◽  
Rainy Season ◽  
Feeding Habits ◽  
Niche Overlap ◽  
Trophic Niche ◽  
Freshwater Ecosystems ◽  
Use Of Resources ◽  
Trophic Resources ◽  
Tropical Areas ◽  
Dry Seasons

The knowledge of the diet of aquatic insects is important to assess the use of resources and overlap of trophic niche between species, as well as to understand their role in the food web of the freshwater ecosystems they inhabit. This is particularly necessary in tropical areas where information on this topic is scarce. The aim of the present work is to describe the feeding habits of the species Anacroneuria marta Zúñiga and Stark, 2002 and Anacroneuria caraca Stark, 1995 in the middle section of the Gaira River (Sierra Nevada de Santa Marta, Colombia). We performed three samplings during the rainy and dry seasons in the two main different microhabitats of the reach (leaf packs and gravel) in 2014. The diet of a total of 87 and 90 individuals of A. caraca and A. marta, respectively, was studied. With this information, niche breadth for each species and niche overlap between them in terms of trophic resources were calculated. The main trophic resource for both species in the dry and rainy season was the animal matter. In the dry season, FPOM was also important in the diet of A. caraca, and A. marta ingested a great quantity of CPOM in the rainy season. Larvae of Trichoptera, were the most ingested prey in both species, followed by Chironomidae, Coleoptera Hydrophilidae, and Ephemeroptera. No differences in diet between both species were detected, so this could favor the niche overlap in terms of trophic resources and could lead to competition between them. The possible ecological scenarios are discussed.

scholarly journals Large-scale patterns in the community structure and biodiversity of freeliving nematodes in the Bohai Sea, China

2001 ◽  
Vol 81 (5) ◽  
pp. 755-763 ◽  
Author(s):  
Y. Guo ◽  
P.J. Somerfield ◽  
R.M. Warwick ◽  
Z. Zhang
Keyword(s):  
Community Structure ◽  
Environmental Variables ◽  
Large Scale ◽  
Bohai Sea ◽  
Yellow River ◽  
River Mouth ◽  
Sediment Surface ◽  
Similar Species ◽  
Taxonomic Distinctness ◽  
The Bohai Sea

Freeliving marine nematodes were sampled on two occasions from an extensive grid of 20 stations in the Bohai Sea and its approaches. Differences within stations between sampling periods were small, resulting from small changes in abundance of dominant species. Differences between stations were significant, and were used to cluster stations into groups with similar species composition. These station groupings revealed a weak faunal gradient leading from the mouth of the Huanghe (Yellow River) to the Bohai Strait. Analyses relating faunal composition to environmental variables showed that there were significant differences in environmental variables between faunally-defined groups of stations. The variables most closely correlated with community structure were silt/clay and sand, depth, phaeopigment concentrations below the sediment surface, organic content and arsenic. These reflect natural processes within the Bohai Sea. A suite of univariate measures were related to distance from the river mouth, with a major discontinuity about 120 km into the Bohai Sea. Comparison of values of the biodiversity measures average taxonomic distinctness (Δ+) and variation in taxonomic distinctness (Λ+) suggest that the meiobenthos of the Bohai Sea as a whole is not under major pollution stress.

The principle of equal opportunity: a test with desert rodents

1982 ◽  
Vol 60 (8) ◽  
pp. 1968-1972 ◽  
Author(s):  
Robert T. M'Closkey
Keyword(s):  
Basic Assumption ◽  
Equal Opportunity ◽  
Niche Overlap ◽  
Rodent Species ◽  
Limited Resources ◽  
Limiting Similarity ◽  
Desert Rodents ◽  
Desert Rodent ◽  
Coexisting Species ◽  
Microhabitat Structure

A basic assumption of the theory of niche overlap and limiting similarity is that the use of limited resources by coexisting species is proportional to resource availability. I provide a test of this assumption with desert rodents using microhabitat structure as a resource. Utilized and available microhabitat frequencies were compared in four desert rodent species. Some rodent species departed significantly in utilized microhabitats from that expected on the basis of availability. However, cumulative utilization frequencies for all four rodent species corresponded closely to the frequency of available microhabitats. Therefore, the assumption of constant ratios of utilization/availability of resources (microhabitats) was not falsified for the entire guild, although individual rodent species used some microhabitats disproportionately.

scholarly journals Functional niche occupation and species richness in herbaceous plant communities along experimental gradients of stress and disturbance

2019 ◽  
Vol 124 (5) ◽  
pp. 861-867
Author(s):  
Yuanzhi Li ◽  
Bill Shipley
Keyword(s):  
Species Richness ◽  
Environmental Gradients ◽  
Experimental System ◽  
Niche Overlap ◽  
Functional Trait ◽  
Limiting Similarity ◽  
Herbaceous Plant ◽  
Habitat Filtering ◽  
Intraspecific Trait Variation ◽  
Different Levels

Abstract Background and Aims The patterns of niche occupation in functional trait space have been widely studied to understand the processes of community assembly, but are rarely linked to environmental conditions (here, stress and disturbance). In this study, we investigate (1) how the pattern of functional niche occupation, incorporating intraspecific trait variation and covariation, varies along experimental gradients of stress and disturbance, (2) whether habitat filtering and/or limiting similarity modify the pattern, and (3) whether their strength varies as a function of species richness or levels of stress and disturbance. Methods We constructed an experimental system consisting of 24 herbaceous plant mesocosms under different levels of stress and disturbance, and measured ten traits on five individuals for each species in each mesocosm. We quantified the total functional niche volume occupied by an entire mesocosm, the functional niche overlap among species within a mesocosm and the average functional niche volume occupied per species, and investigated how these metrics varied from species-poor to species-rich mesocosms along gradients of stress and disturbance. Key Results Species richness and functional niche overlap correlated positively to disturbance at low and medium levels of stress, but peaked at the intermediate level of disturbance when stress was high. The total functional niche volume and average functional niche volume did not change significantly along these gradients. Compared to null models, each mesocosm occupied a smaller total functional niche volume (habitat filtering) and the species within each mesocosm overlapped less and were more functionally specialized (limiting similarity). Moreover, the standardized metrics (to the null expectations) did not change significantly under different levels of stress and disturbance. Conclusions This experimental evidence shows that both habitat filtering and limiting similarity determine the patterns of functional niche occupation and species richness, but their strength does not change along environmental gradients of stress and disturbance.

scholarly journals Dynamics of ammonium and pH in the solution of soils with different salinity levels, growing irrigated rice

2012 ◽  
Vol 36 (2) ◽  
pp. 401-409
Author(s):  
Felipe de Campos Carmona ◽  
Ibanor Anghinoni ◽  
Eduardo Giacomelli Cao
Keyword(s):  
Soil Solution ◽  
Field Experiments ◽  
N Uptake ◽  
Coastal Region ◽  
Rio Grande Do Sul ◽  
Irrigated Rice ◽  
Lower Salinity ◽  
Salinity Levels ◽  
Pronounced Reduction ◽  
Over Time

Rice in Rio Grande do Sul State is grown mostly under flooding, which induces a series of chemical, physical and biological changes in the root environment. These changes, combined with the presence of rice plants, affect the availability of exchangeable ammonium (NH4+) and pH of soil solution, whereas the dynamics of both variables can be influenced by soil salinity, a common problem in the coastal region. This study was conducted to evaluate the dynamics of exchangeable NH4+ and pH in the soil solution, and their relation in the solution of Albaqualf soils with different salinity levels, under rice. Four field experiments were conducted with soils with exchangeable Na percentage (ESP) of 5.6, 9.0, 21.2, and 32.7 %. Prior to flooding, soil solution collectors were installed at depths of 5, 10 and 20 cm. The soil solution was collected weekly, from 7 to 91 days after flooding (DAF), to analyze exchangeable NH4+ and pH in the samples. Plant tissue was sampled 77 DAF, to determine N uptake and estimate the contribution of other N forms to rice nutrition. The content of exchangeable NH4+ decreased over time at all sites and depths, with a more pronounced reduction in soils with lower salinity levels, reaching values close to zero. A possible contribution of non-exchangeable NH4+ forms and N from soil organic matter to rice nutrition was observed. Soil pH decreased with time in soils with ESP 5.6 and 9.0 %, being positively correlated with the decreasing NH4+ levels at these sites.

Seasonal group characteristics and occurrence patterns of Indo-Pacific humpback dolphins (Sousa chinensis) in Xiamen Bay, Fujian Province, China

2016 ◽  
Vol 97 (4) ◽  
pp. 1026-1032 ◽  
Author(s):  
Xianyan Wang ◽  
Fuxing Wu ◽  
Samuel T. Turvey ◽  
Massimiliano Rosso ◽  
Qian Zhu
Keyword(s):  
River Estuary ◽  
Wet Season ◽  
Jiulong River Estuary ◽  
Xiamen Bay ◽  
Encounter Rates ◽  
Dry Seasons ◽  
Sousa Chinensis ◽  
Peripheral Areas ◽  
Occurrence Patterns ◽  
Group Characteristics

Abstract Monthly field surveys were conducted between August 2010 and July 2015 to explore seasonal group characteristics and occurrence patterns of Indo-Pacific humpback dolphins (Sousa chinensis) in Xiamen Bay, China. Dolphins formed larger groups in winter and spring (dry seasons) than in summer and autumn (wet seasons; U = 1,564.00, P < 0.001). Sighting encounter rates were higher during the wet season than during the dry season (U = 181.00, P < 0.001), while individual encounter rates were not significantly different between seasons (F = 0.494, d.f. = 3, P = 0.688). Dolphin sightings and the foraging events were mainly found in inner harbors (Western Harbour and Tongan Bay) during the dry seasons and in peripheral areas (Jiulong River Estuary, Wuyu, and Dadeng-Xiaodeng) during the wet seasons. Seasonal occurrence patterns may be associated with the seasonal prey shifts between these different environments.

scholarly journals Is coexistence between non-native and native Erythrinidae species mediated by niche differentiation or environmental filtering? A case study in the upper Paraná River floodplain

2017 ◽  
Vol 15 (2) ◽  
Author(s):  
Larissa S. Pereira ◽  
Fábio T. Mise ◽  
Luiz F. C. Tencatt ◽  
Matheus T. Baumgartner ◽  
Angelo A. Agostinho
Keyword(s):  
Introduced Species ◽  
Functional Traits ◽  
Native Species ◽  
Species Coexistence ◽  
Niche Breadth ◽  
Similarity Theory ◽  
Environmental Filtering ◽  
Niche Differentiation ◽  
Limiting Similarity ◽  
Environmental Filters

ABSTRACT The limiting similarity theory predicts that divergence in the functional traits of native and introduced species is an essential component in species establishment, as introduced species must occupy a niche that is unoccupied by resident species. On the other hand, the environmental filtering hypothesis predicts convergence between introduced and native species, as both possess traits that make them adapted to the local abiotic environment. Morphology, spatial co-occurrence, diet, feeding selectivity, and niche breadth and overlap of Erythrinidae were evaluated to detect possible mechanisms acting in the coexistence between non-native and native species. Native (Hoplias sp. B and Hoplias cf. malabaricus) and non-native (Hoplerythrinus unitaeniatus and Hoplias mbigua) species presented differences in morphological traits, spatial co-occurrence, diet, selectivity, and niche breadth and overlap. The mechanisms mediating species coexistence seem to vary according to species. The absence of spatial and feeding overlap suggests that non-native species H. unitaeniatus occupy a different niche than native species, supporting its successful establishment without eliminating the native species. However, low feeding overlap and similar morphologies between non-native and native species of Hoplias point to environmental filters; in this case, the non-native H. mbigua is able to establish due to similarities in functional traits.

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