scholarly journals Indicator environmental variables in regulating the distribution patterns of small freshwater fish Amblypharyngodon mola in India and Bangladesh

2021 ◽  
Vol 120 ◽  
pp. 106906
Author(s):  
Sangeeta Roy ◽  
Santanu Ray ◽  
Surjya Kumar Saikia
Keyword(s):  
Freshwater Fish ◽  
Environmental Variables ◽  
Distribution Patterns

scholarly journals Distribution Patterns of Odonate Assemblages in Relation to Environmental Variables in Streams of South Korea

Insects ◽  
2018 ◽  
Vol 9 (4) ◽  
pp. 152 ◽  
Author(s):  
Da-Yeong Lee ◽  
Dae-Seong Lee ◽  
Mi-Jung Bae ◽  
Soon-Jin Hwang ◽  
Seong-Yu Noh ◽  
...  
Keyword(s):  
Land Use ◽  
Ecosystem Services ◽  
Environmental Factors ◽  
South Korea ◽  
Habitat Heterogeneity ◽  
Environmental Variables ◽  
Environmental Changes ◽  
Distribution Patterns ◽  
Self Organizing Map ◽  
Factors Affecting

Odonata species are sensitive to environmental changes, particularly those caused by humans, and provide valuable ecosystem services as intermediate predators in food webs. We aimed: (i) to investigate the distribution patterns of Odonata in streams on a nationwide scale across South Korea; (ii) to evaluate the relationships between the distribution patterns of odonates and their environmental conditions; and (iii) to identify indicator species and the most significant environmental factors affecting their distributions. Samples were collected from 965 sampling sites in streams across South Korea. We also measured 34 environmental variables grouped into six categories: geography, meteorology, land use, substrate composition, hydrology, and physicochemistry. A total of 83 taxa belonging to 10 families of Odonata were recorded in the dataset. Among them, eight species displayed high abundances and incidences. Self-organizing map (SOM) classified sampling sites into seven clusters (A–G) which could be divided into two distinct groups (A–C and D–G) according to the similarities of their odonate assemblages. Clusters A–C were characterized by members of the suborder Anisoptera, whereas clusters D–G were characterized by the suborder Zygoptera. Non-metric multidimensional scaling (NMDS) identified forest (%), altitude, and cobble (%) in substrata as the most influential environmental factors determining odonate assemblage compositions. Our results emphasize the importance of habitat heterogeneity by demonstrating its effect on odonate assemblages.

Climate Defined but Not Soil-restricted: The Distribution of a Neotropical tree through Space and Time

2021 ◽  
Author(s):  
Facundo Alvarez ◽  
Paulo S Morandi ◽  
Ben Hur Marimon-Junior ◽  
Reginal Exavier ◽  
Igor Araújo ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Environmental Variables ◽  
Distribution Patterns ◽  
Distribution Models ◽  
Climatic Fluctuations ◽  
Space And Time ◽  
Predictive Variables ◽  
Soil Variables ◽  
Neotropical Tree ◽  
Edaphic Variables

Abstract AimsBrosimum rubescens, a tree species with a Neotropical distribution, can achieve local monodominance in Southern Amazonia forests. Understanding how and why this species varies across space and time is important because the monodominance of some species alters ecosystems complexity. Here we evaluate the fundamental ecological niche of B. rubescens by species distribution models (SDM), combining predictive environmental variables with occurrence points. We specifically aim to 1) determine how the spatial distribution patterns of B. rubescens vary with different environmental predictive variables, and 2) evaluate the temporal and spatial persistence of B. rubescens in the Neotropics. MethodsTo generate the SDMs, the predictive environmental variables were incorporated as main components of climatic, hydric and soil variables. ResultsAll algorithms show higher performance in spatial predictions for hydric variables and for the combination of climatic, hydric and edaphic variables. We identified that the potential niches of B. rubescens seem to be defined by climatic fluctuations, with the edaphic conditions being predictive variables that are not restrictive of their presence on the evaluated spatial scale. From the LMG (Last Glacial Maximum) to the present, the species seems to have increased its spatial amplitude; however, from the present to the future, predictions suggest that B. rubescens will experience a considerable loss of its range. ConclusionsOur findings show the independent and combined effects of different environmental variables, allowing us to identify which limit or facilitate the spatial distribution of B. rubescens. We corroborate the spatial persistence and geographical fidelity of the species' spatial patterns over time.

scholarly journals Diversity and Distribution Patterns of Geometrid Moths (Geometridae, Lepidoptera) in Mongolia

Diversity ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 186
Author(s):  
Khishigdelger Enkhtur ◽  
Bazartseren Boldgiv ◽  
Martin Pfeiffer
Keyword(s):  
Species Richness ◽  
Environmental Variables ◽  
Environmental Changes ◽  
Distribution Patterns ◽  
Maximum Temperature ◽  
Forest Steppe ◽  
Global Biodiversity Information Facility ◽  
Scientific Papers ◽  
Geometrid Moth ◽  
Biodiversity Information

Geometrids are a species-rich group of moths that serve as reliable indicators for environmental changes. Little is known about the Mongolian moth fauna, and there is no comprehensive review of species richness, diversity, and distribution patterns of geometrid moths in the country. Our study aims to review the existing knowledge on geometrid moths in Mongolia. We compiled geometrid moth records from published scientific papers, our own research, and from the Global Biodiversity Information Facility (GBIF) to produce a checklist of geometrid moths of Mongolia. Additionally, we analyzed spatial patterns, species richness, and diversity of geometrid moths within 14 ecoregions of Mongolia and evaluated environmental variables for their distribution. In total, we compiled 1973-point records of 388 geometrid species. The most species-rich ecoregion in Mongolia was Daurian Forest Steppe with 142 species. Annual precipitation and maximum temperature of the warmest month were the most important environmental variables that correlated with NMDS axes in an analysis of geometrid assemblages of different ecoregions in Mongolia.

scholarly journals River density and landscape roughness are universal determinants of linguistic diversity

2014 ◽  
Vol 281 (1784) ◽  
pp. 20133029 ◽  
Author(s):  
Jacob Bock Axelsen ◽  
Susanna Manrubia
Keyword(s):  
Environmental Variables ◽  
Biological Diversity ◽  
Linguistic Diversity ◽  
Distribution Patterns ◽  
Spatial Diversity ◽  
Heterogeneous Distribution ◽  
Changing Environments ◽  
The Pacific ◽  
Geographical Regions ◽  
Alternative Scenarios

Global linguistic diversity (LD) displays highly heterogeneous distribution patterns. Though the origin of the latter is not yet fully understood, remarkable parallelisms with biodiversity distribution suggest that environmental variables should play an essential role in their emergence. In an effort to construct a broad framework to explain world LD and to systematize the available data, we have investigated the significance of 14 variables: landscape roughness, altitude, river density, distance to lakes, seasonal maximum, average and minimum temperature, precipitation and vegetation, and population density. Landscape roughness and river density are the only two variables that universally affect LD. Overall, the considered set accounts for up to 80% of African LD, a figure that decreases for the joint Asia, Australia and the Pacific (69%), Europe (56%) and the Americas (53%). Differences among those regions can be traced down to a few variables that permit an interpretation of their current states of LD. Our processed datasets can be applied to the analysis of correlations in other similar heterogeneous patterns with a broad spatial distribution, the clearest example being biological diversity. The statistical method we have used can be understood as a tool for cross-comparison among geographical regions, including the prediction of spatial diversity in alternative scenarios or in changing environments.

scholarly journals Spatial scales of interannual recruitment variations of marine, anadromous, and freshwater fish

1997 ◽  
Vol 54 (6) ◽  
pp. 1400-1407 ◽  
Author(s):  
R A Myers ◽  
G Mertz ◽  
J Bridson
Keyword(s):  
Spatial Scale ◽  
Freshwater Fish ◽  
Marine Environment ◽  
Environmental Variables ◽  
Large Scale ◽  
Spatial Scales ◽  
Marine Species ◽  
Freshwater Species ◽  
Environmental Agents

We examine the spatial scale of variability in recruitment for 11 marine, three anadromous, and five freshwater species. Generally the spatial scale of recruitment correlations for marine species is approximately 500 km, compared with less than 50 km for freshwater; anadromous species fall between these two scales. The scale for marine species is comparable with (but less than) that of the largest-scale environmental variables (and is compatible with the idea that large-scale environmental agents influence recruitment). Our results are consistent with the hypothesis that predation is a more important factor in determining recruitment in freshwater than it is in the marine environment.

Dietary Variation in a Freshwater Fish Species: Relative Contributions of Biotic Interactions, Abiotic Factors, and Spatial Structure

1994 ◽  
Vol 51 (12) ◽  
pp. 2856-2865 ◽  
Author(s):  
Pierre Magnan ◽  
Marco A. Rodríguez ◽  
Pierre Legendre ◽  
Sylvain Lacasse
Keyword(s):  
Spatial Structure ◽  
Freshwater Fish ◽  
Fish Species ◽  
Environmental Variables ◽  
Brook Trout ◽  
Diet Composition ◽  
Abiotic Factors ◽  
Biotic Interactions ◽  
Relative Contribution ◽  
Dietary Variation

We used multivariate analyses to examine which variables among the environmental and spatial components can best account for dietary variation in a freshwater fish, brook trout, Salvelinus fontinalis. The diet composition of brook trout was quantified in 37 lakes of the Laurentian Shield, Québec, Canada. Among the 25 measured environmental variables, fish species composition, sampling date, macrophyte abundance, and trout body length were the best predictors of diet composition. The total variation in diet composition was partitioned into four components: pure environmental 21.6%, pure spatial 23.2%, shared 19.9%, and unexplained 35.3%. A significant spatial trend in diet composition existed even after accounting for the main effects measured by the environmental variables. The two sets of spatial variables, when combined with the environmental descriptors, extracted different components of the dietary variation. The study allowed us to (1) highlight the role of spatial structure in diet variation of brook trout, (2) determine the relative contribution of both environmental and spatial components, and (3) generate testable hypotheses concerning mechanisms underlying the observed structure. Dependent variables other than diet composition, such as the density of different species at different sampling sites, can be used within the same statistical framework in studies of community ecology.

Composition and distribution patterns of eukaryotic microbial plankton in the ultra-oligotrophic Eastern Mediterranean Sea

2020 ◽  
Vol 84 ◽  
pp. 155-173
Author(s):  
I Santi ◽  
P Kasapidis ◽  
S Psarra ◽  
G Assimakopoulou ◽  
A Pavlidou ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Deep Sea ◽  
Environmental Variables ◽  
Eastern Mediterranean ◽  
Distribution Patterns ◽  
Eastern Mediterranean Sea ◽  
Operational Taxonomic Units ◽  
Microbial Eukaryotes ◽  
Levantine Basin ◽  
Microbial Plankton

Marine microbial eukaryotes play crucial roles in water-column ecosystems; however, there are regional gaps in the investigation of natural microbial eukaryote communities, and uncertainties concerning their distribution persevere. This study combined 18S rRNA metabarcoding, biomass measurements and statistical analyses of multiple environmental variables to examine the distribution of planktonic microbial eukaryotes at different sites and water layers in the ultra-oligotrophic Eastern Mediterranean Sea (Western Levantine Basin). Our results showed that microbial eukaryotic communities were structured by depth. In surface waters, different sites shared high percentages of molecular operational taxonomic units (MOTUs), but this was not the case for deep-sea communities (≥1000 m). Plankton biomass was significantly different among sites, implying that communities of a similar composition may not support the same activity or population size. The deep-sea communities showed high percentages of unassigned MOTUs, highlighting the sparsity of the existing information on deep-sea plankton eukaryotes. Water temperature and dissolved organic matter significantly affected community distribution. Micro-eukaryotic distribution was additionally affected by the nitrogen to phosphorus ratio and viral abundance, while nano- and pico-communities were affected by zooplankton. The present study explores microbial plankton eukaryotes in their natural oligotrophic environment and highlights that, even within restricted oceanic areas, marine plankton may follow distribution patterns that are largely controlled by environmental variables.

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