scholarly journals Fish beta diversity responses to environmental heterogeneity and flood pulses are different according to reproductive guild

2018 ◽  
Vol 16 (4) ◽  
Author(s):  
Ángela Gutiérrez C ◽  
Jean Carlo Gonçalves Ortega ◽  
Angelo Antonio Agostinho
Keyword(s):  
Parental Care ◽  
Beta Diversity ◽  
Environmental Heterogeneity ◽  
Linear Models ◽  
Fish Assemblages ◽  
Generalized Least Squares ◽  
The Other ◽  
Dispersal Capacity ◽  
Reproductive Guilds ◽  
Reproductive Guild

ABSTRACT In floodplain communities, beta diversity is influenced by different factors; however, environmental heterogeneity and floods are believed to be particularly influential. The influence of environmental heterogeneity and floods on beta diversity may vary among guilds that present different ecological traits. This study evaluated the correlation between the environmental heterogeneity and flood periods and the beta diversity of trophic and reproductive guilds of fish assemblages. Sampling was conducted quarterly between 2000 and 2012 in the upper Paraná River floodplain. The environmental heterogeneity and period (i.e., dry or flood) were associated with the beta diversity of each guild based on the results of generalized least squares linear models. Only guilds with parental care were influenced by the interaction between environmental heterogeneity and period. The beta diversity of the other guilds presented no relationship between environmental heterogeneity and period. It is likely that species with parental care presented less dispersal capacity, which increased the dissimilarity among assemblages. The higher dispersion rates of the other guilds may be responsible for the lack of relationship between the beta diversity and the environmental heterogeneity and period. In sum, these results suggest that reproductive guilds influence how environmental heterogeneity and floods affect beta diversity variation.

scholarly journals Effects of urbanization and environmental heterogeneity on fish assemblages in small streams

2021 ◽  
Vol 19 (3) ◽  
Author(s):  
Jean C. G. Ortega ◽  
Iussa Bacani ◽  
Tainá F. Dorado-Rodrigues ◽  
Christine Strüssmann ◽  
Izaias M. Fernandes ◽  
...  
Keyword(s):  
Fish Species ◽  
Native Species ◽  
Poecilia Reticulata ◽  
Environmental Heterogeneity ◽  
Linear Models ◽  
Fish Assemblages ◽  
Small Streams ◽  
Species Abundances ◽  
Local Contribution ◽  
Negative Impacts

Abstract The structure of freshwater assemblages may be driven directly by urbanization or indirectly by a reduction in environmental heterogeneity (EH). Disentangling the effects of urbanization and EH requires uncorrelated proxies of each of these factors. We assessed the effects of the degree of urbanization and EH on the structure of fish assemblages. We sampled fish in 45 streams located in the urban area of Cuiabá. We assessed the effects of urbanization and EH on rarefied fish species richness (Srarefied), the local contribution to beta diversity (LCBD), and composition with linear models and distance-based redundancy analysis. Our indexes of urbanization and EH were not correlated. We found that both Srarefied and the LCBD decreased with an increasing degree of urbanization, but were not associated with EH. We also noted that few native fish species abundances were associated with the EH. Serrapinnus microdon, S. calliurus, Hemigrammus tridens, and Astyanax lacustris were abundant in streams with a lower degree of urbanization. The non-native Poecilia reticulata was more abundant in streams with a higher degree of urbanization. Our results highlight that urbanization leads in negative impacts on fish assemblages, such as decreases in diversity and the dominance of non-native species.

scholarly journals Environmental heterogeneity explains species turnover but not nestedness in fish assemblages of a Neotropical basin

2017 ◽  
Vol 29 (0) ◽  
Author(s):  
Oscar Eduardo Peláez ◽  
Filipe Manoel Azevedo ◽  
Carla Simone Pavanelli
Keyword(s):  
Species Composition ◽  
Beta Diversity ◽  
Environmental Variables ◽  
Environmental Heterogeneity ◽  
Fish Assemblages ◽  
Environmental Gradients ◽  
Species Turnover ◽  
Paraná River ◽  
Fish Diversity ◽  
Parana River

Abstract Aim: Heterogenous environments can contribute to maintain biodiversity. Traditionally beta diversity studies have focused on determining the effect of environmental variables on the total dissimilarity of species composition. However, decomposing beta diversity in species replacement and nestedness could give new insights on mechanisms affecting spatial patterns of biodiversity. We aimed to answer two main questions about spatial patterns of fish diversity in a Neotropical basin: 1) whether some regions contribute differently to fish diversity, and 2) whether species turnover and nestedness are explained by environmental gradients. Methods Sampling sites in the main channel and tributaries of the Upper Paraná River were sampled between 2013 and 2015. We partitioned beta diversity and tested the relationship of turnover and nestedness with environmental variables. Results 74 species were captured. Some of these species were restricted to different sites, contributing to variation in species composition. Hill numbers showed a trend for higher diversity in the tributaries than in Paraná River sampling sites, and the partition of beta diversity revealed that species replacement drove dissimilarity in species composition. Only total beta diversity and turnover were related to environmental variables, mainly conductivity and turbidity. Conclusions Species diversity and composition of fish assemblages in the Upper Paraná River could be related to environmental gradients. Overall, our results suggest that Paraná River tributaries contribute to increase environmental heterogeneity, and hence to maintain a high diversity and variation in species composition. For that reason, we strongly recommend preserving highly heterogeneous habitats in the region.

Human density, economic level and frequency of canine helminths in Buenos Aires

2021 ◽  
Vol 95 ◽  
Author(s):  
D. Rubel ◽  
N. Flaibani
Keyword(s):  
Linear Models ◽  
Buenos Aires ◽  
Toxocara Canis ◽  
The Other ◽  
Green Spaces ◽  
Cross Sectional ◽  
Independent Variables ◽  
Economic Level ◽  
Faecal Samples ◽  
Human Density

Abstract The aim of this study was to explore through cross-sectional study the variation in the prevalence of parasitic helminths in canine faeces collected from green spaces of Buenos Aires according to the human density (HD) and economic level (EL) in the surroundings. HD and EL were considered as independent variables with three categories each. Twenty public squares (one hectare of surface) were randomly selected for each existing combination of the two independent variables. Ten random samples of fresh canine faeces were obtained in each square and analysed for helminths by the sedimentation and flotation techniques. The prevalence for each of the species was analysed using generalized linear models (GLM). The prevalence was modelled with a binomial error distribution and a logit link function. Helminth eggs were detected in 45 out of the 200 (22.5%) faecal samples collected and in 18 of the 20 green spaces sampled. The species observed were Ancylostoma caninum (13% of samples), Trichuris vulpis (8%) and Toxocara canis (4.5%). The GLM indicated that the prevalence of A. caninum in the slum areas (very high HD and very low EL) was higher than that in the other areas studied. However, the HD seemed to contribute more than the EL to the variations in the prevalence of A. caninum in faecal samples. The GLM showed no differences in the prevalence of the other parasite species for the different levels of the independent variables.

scholarly journals Relationship between Cycling Infrastructure and Transportation Cycling in a Small Urban Area

2021 ◽  
Vol 1 (1) ◽  
pp. 99-112
Author(s):  
Richard Larouche ◽  
Nimesh Patel ◽  
Jennifer L. Copeland
Keyword(s):  
Generalized Linear Models ◽  
Qualitative Data ◽  
Linear Models ◽  
The Other ◽  
Small City ◽  
The Road ◽  
The Past ◽  
Low Prevalence ◽  
The Relationship

The role of infrastructure in encouraging transportation cycling in smaller cities with a low prevalence of cycling remains unclear. To investigate the relationship between the presence of infrastructure and transportation cycling in a small city (Lethbridge, AB, Canada), we interviewed 246 adults along a recently-constructed bicycle boulevard and two comparison streets with no recent changes in cycling infrastructure. One comparison street had a separate multi-use path and the other had no cycling infrastructure. Questions addressed time spent cycling in the past week and 2 years prior and potential socio-demographic and psychosocial correlates of cycling, including safety concerns. Finally, we asked participants what could be done to make cycling safer and more attractive. We examined predictors of cycling using gender-stratified generalized linear models. Women interviewed along the street with a separate path reported cycling more than women on the other streets. A more favorable attitude towards cycling and greater habit strength were associated with more cycling in both men and women. Qualitative data revealed generally positive views about the bicycle boulevard, a need for education about sharing the road and for better cycling infrastructure in general. Our results suggest that, even in smaller cities, cycling infrastructure may encourage cycling, especially among women.

scholarly journals Local-scale determinants of arboreal spider beta diversity in a temperate forest: roles of tree architecture, spatial distance, and dispersal capacity

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5596 ◽  
Author(s):  
Qiongdao Zhang ◽  
Dong He ◽  
Hua Wu ◽  
Wei Shi ◽  
Cong Chen
Keyword(s):  
Beta Diversity ◽  
Environmental Gradient ◽  
Dispersal Limitation ◽  
Local Scale ◽  
Tree Architecture ◽  
Habitat Specialization ◽  
Spatial Distance ◽  
Species Variation ◽  
Dispersal Capacity ◽  
Canopy Volume

Spiders are a functionally important taxon in forest ecosystems, but the determinants of arboreal spider beta diversity are poorly understood at the local scale. We examined spider assemblages in 324 European beech (Fagus sylvatica) trees of varying sizes across three forest stands in Würzburg (Germany) to disentangle the roles of tree architecture, spatial distance, and dispersal capacity on spider turnover across individual trees. A large proportion of tree pairs (66%) showed higher compositional dissimilarity in spider assemblages than expected by chance, suggesting prominent roles of habitat specialization and/or dispersal limitation. Trees with higher dissimilarity in DBH and canopy volume, and to a lesser extent in foliage cover, supported more dissimilar spider assemblages, suggesting that tree architecture comprised a relevant environmental gradient of sorting spider species. Variation partitioning revealed that 28.4% of the variation in beta diversity was jointly explained by tree architecture, spatial distance (measured by principal coordinates of neighbor matrices) and dispersal capacity (quantified by ballooning propensity). Among these, dispersal capacity accounted for a comparable proportion as spatial distance did (6.8% vs. 5.9%). Beta diversity did not significantly differ between high- and low-vagility groups, but beta diversity in species with high vagility was more strongly determined by spatially structured environmental variation. Altogether, both niche specialization, along the environmental gradient defined by tree architecture, and dispersal limitation are responsible for structuring arboreal spider assemblages. High dispersal capacity of spiders appears to reinforce the role of niche-related processes.

scholarly journals High beta diversity among small islands is due to environmental heterogeneity rather than ecological drift

2018 ◽  
Vol 45 (10) ◽  
pp. 2252-2261 ◽  
Author(s):  
Jinliang Liu ◽  
Mark Vellend ◽  
Zuhua Wang ◽  
Mingjian Yu
Keyword(s):  
Beta Diversity ◽  
Environmental Heterogeneity ◽  
Small Islands ◽  
High Beta ◽  
Ecological Drift

scholarly journals Implementation of the mixed linear models in experimental infections with WSSV in the withe shrimp Litopenaeus vannamei

2017 ◽  
Vol 43 (3) ◽  
pp. 557-565
Author(s):  
María Alejandra Ramírez-Ruíz ◽  
Raúl Simá-Álvarez ◽  
Edgar Tórres-Irineo ◽  
Rossanna Rodríguez-Canul
Keyword(s):  
Litopenaeus Vannamei ◽  
Host Response ◽  
White Spot Syndrome Virus ◽  
Linear Models ◽  
Severe Infection ◽  
The Other ◽  
Mixed Linear Models ◽  
Dna Injection ◽  
Shrimp Industry ◽  
Experimental Strategies

The White Spot Syndrome Virus has been very detrimental for the shrimp industry. Up to date there is no cure for the disease, thus, it is necessary to implement reliable experimental strategies to evaluate the effect of drugs and the host response during the prognosis of the disease. In this study, we evaluated two ways of infection with WSSV (200 copies WSSV-DNA) (injection and immersion), at constant temperature (26 ± 0.5ºC), in juveniles of Litopenaeus vannamei (4.8 ± 0.38 g) in intermolt stage. In the infection by injection, the organisms were lethargic with reddish appearance 2 days after infection and mortality (100%) was observed within 2-5 days: 63% organisms with light degree of infection [20 copies of DNA & 1-5 Cowdry A-type inclusions in hypertrophied nuclei (CAI)/200 fields], 21% had moderate infection (200 copies of DNA & 1-2 CAI/20 fields) and 16% severely infected (2000 copies of DNA & more than 10 CAI/field). No mortality was observed in the controls. In the infection by immersion, the signs of WSSV were observed 3 days after infection: 38% of mortality was observed during 3-9 days: 25% of the organism with light degree of infection (20 copies of DNA & 1-2 CAI/20 fields), 5% moderately infected (200 copies of DNA & 1-2 CAI/20 fields) and 8% with severe infection (2000 copies of DNA & 1-5 CAI/2 fields. The other 62% organisms were necropsied at day 12 and tested positive to the WSSV-PCR (light infection = 20 copies of DNA), but did not show CAI by histology. No mortality was observed in the controls. For the statistical analysis, the data did not fit the criteria of independence and linearity needed for the analyses of variance, thus we used instead the mixed linear models and were able to observe a better prediction: in the injected organisms, the mortality reached the highest peak at day 5 after infection. In the organisms infected by immersion, the highest peak or mortality was observed at day 9 after infection. The analysis of variance of Kenward-Roger indicated significant differences between the days of mortality (F = 20.1, P = 0.001), as well as among the ways of infection (Random analysis) (P = 0.007).

scholarly journals Environmental and historical imprints on beta diversity: insights from variation in rates of species turnover along gradients

2013 ◽  
Vol 280 (1768) ◽  
pp. 20131201 ◽  
Author(s):  
Matthew C. Fitzpatrick ◽  
Nathan J. Sanders ◽  
Signe Normand ◽  
Jens-Christian Svenning ◽  
Simon Ferrier ◽  
...  
Keyword(s):  
Beta Diversity ◽  
Linear Models ◽  
Species Turnover ◽  
Ecological Systems ◽  
Climate History ◽  
Northern European ◽  
Species Similarity ◽  
Southwest Australia ◽  
Novel Method ◽  
Curvilinear Relationships

A common approach for analysing geographical variation in biodiversity involves using linear models to determine the rate at which species similarity declines with geographical or environmental distance and comparing this rate among regions, taxa or communities. Implicit in this approach are weakly justified assumptions that the rate of species turnover remains constant along gradients and that this rate can therefore serve as a means to compare ecological systems. We use generalized dissimilarity modelling, a novel method that accommodates variation in rates of species turnover along gradients and between different gradients, to compare environmental and spatial controls on the floras of two regions with contrasting evolutionary and climatic histories: southwest Australia and northern Europe. We find stronger signals of climate history in the northern European flora and demonstrate that variation in rates of species turnover is persistent across regions, taxa and different gradients. Such variation may represent an important but often overlooked component of biodiversity that complicates comparisons of distance–decay relationships and underscores the importance of using methods that accommodate the curvilinear relationships expected when modelling beta diversity. Determining how rates of species turnover vary along and between gradients is relevant to understanding the sensitivity of ecological systems to environmental change.

scholarly journals Beta Diversity Partitioning and Drivers of Variations in Fish Assemblages in a Headwater Stream: Lijiang River, China

Water ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 680 ◽  
Author(s):  
Liangliang Huang ◽  
Jian Huang ◽  
Zhiqiang Wu ◽  
Yuanmin Mo ◽  
Qi Zou ◽  
...  
Keyword(s):  
Species Composition ◽  
Beta Diversity ◽  
Fish Assemblages ◽  
Headwater Streams ◽  
Species Turnover ◽  
Diversity Partitioning ◽  
Spatial Variables ◽  
Lijiang River ◽  
Abiotic Variables ◽  
Hydrological Variables

Beta diversity partitioning has currently received much attention in research of fish assemblages. However, the main drivers, especially the contribution of spatial and hydrological variables for species composition and beta diversity of fish assemblages are less well studied. To link species composition to multiple abiotic variables (i.e., local environmental variables, hydrological variables, and spatial variables), the relative roles of abiotic variables in shaping fish species composition and beta diversity (i.e., overall turnover, replacement, and nestedness) were investigated in the upstream Lijiang River. Species composition showed significant correlations with environmental, hydrological, and spatial variables, and variation partitioning revealed that the local environmental and spatial variables outperformed hydrological variables, and especially abiotic variables explained a substantial part of the variation in the fish composition (43.2%). The overall species turnover was driven mostly by replacement (87.9% and 93.7% for Sørensen and Jaccard indices, respectively) rather than nestedness. Mantel tests indicated that the overall species turnover (ßSOR and ßJAC) and replacement (ßSIM and ßJTU) were significantly related to hydrological, environmental, and spatial heterogeneity, whereas nestedness (ßSNE or ßJNE) was insignificantly correlated with abiotic variables (P > 0.05). Moreover, the pure effect of spatial variables on overall species turnover (ßSOR and ßJAC) and replacement (ßSIM and ßJTU), and the pure effect of hydrological variables on replacement (ßSIM and ßJTU), were not important (P > 0.05). Our findings demonstrated the relative importance of interactions among environmental, hydrological, and spatial variables in structuring fish assemblages in headwater streams; these fish assemblages tend to be compositionally distinct, rather than nested derivatives of one another. Our results, therefore, indicate that maintaining natural flow dynamics and habitat continuity are of vital importance for conservation of fish assemblages and diversity in headwater streams.

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