scholarly journals Structural and Functional Variations of the Macrobenthic Community of the Adige Basin along the River Continuum

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 451
Author(s):  
Mattias Gaglio ◽  
Vassilis Aschonitis ◽  
Alexandra Nicoleta Muresan ◽  
Fabio Vincenzi ◽  
Giuseppe Castaldelli ◽  
...  
Keyword(s):  
Environmental Gradients ◽  
Environmental Parameters ◽  
Taxonomic Diversity ◽  
Macrobenthic Community ◽  
River Continuum ◽  
Local Conditions ◽  
General Validity ◽  
Functional Richness ◽  
Functional Features ◽  
Community Complexity

Since the publication of the River Continuum Concept (RCC), the capacity of the longitudinal dimension to predict the distribution of species and ecological functions in river networks was discussed by different river theories. The taxonomic structures and functional attributes of macrobenthic communities were investigated along the river continuum in the river Adige network (Northern Italy), with the aim to test the reliability of RCC theory and clarify the relation between structural and functional features in lotic systems. Distance from the spring was found to be most representative proxy among environmental parameters. The analysis highlighted the decrease of biodiversity levels along the river continuum. The decrease of taxonomic diversity corresponded to the loss in functional richness. The abundances of predator and walker taxa, as well as semelparous organisms, declined along the longitudinal gradient, suggesting variations in community complexity and granulometry. Regression models also depicted the presence of disturbed communities in the central section of the basin, where intensive agricultural activities occur, that affected environmental gradients. Overall, results offered evidences that the river continuum may predict macrobenthic community structures in terms of taxonomic diversity, thus confirming the general validity of RCC. Nonetheless, the functional analysis did not provide equally clear evidences to support the theory. After four decades from its postulation, the RCC is still a reliable model to predict the general macroinvertebrates distribution. However, community functions may respond to a number of local factors not considered in RCC, which could find a declination in other theories. The relations between structural and functional features confirmed to be complex and sensitive to disturbances and local conditions.

scholarly journals Lokale Anpassung bei Waldbaumarten: genetische Prozesse und Bedeutung im Klimawandel

2016 ◽  
Vol 167 (6) ◽  
pp. 333-340
Author(s):  
Christian Rellstab ◽  
Andrea R. Pluess ◽  
Felix Gugerli
Keyword(s):  
Local Adaptation ◽  
Environmental Gradients ◽  
Management Strategies ◽  
Environmental Parameters ◽  
Forest Trees ◽  
Local Conditions ◽  
Genetic Changes ◽  
Association Analyses ◽  
Temperature And Precipitation ◽  
Technological Advances

Local adaptation in forest trees: genetic processes and relevance under climate change Forest trees will have to adapt to future climatic changes, a process that will comprise genetic changes as a key component. Owing to technological advances it is now possible to identify the signature of natural selection and local adaptation in the genome. Environmental association analyses aim at associating adaptive genetic patterns with environmental parameters describing the local habitat. On the basis of such studies – including own investigations using oak and beech in Switzerland –, we show that forest trees are genetically differentiated along various environmental gradients, especially temperature and precipitation. Numerous genes could be found that presumably play a role in the adaptation to such environmental factors. Based on these findings, one could identify trees or stands that are adapted to future local conditions, and respective seed material could be considered in silviculture. Because such approaches are still in their infancy and because genome-environment interactions are complex, management strategies should focus on the preservation of (adaptive) genetic diversity, natural regeneration, and connectivity among stands. This would set the basis for the local adaptation of forest stands to altered environmental conditions by natural processes.

scholarly journals Seasonal Analysis of Taxonomic and Functional Diversity of Poneromorph Ant Assemblages in the Amazon Forest

Sociobiology ◽  
2016 ◽  
Vol 63 (3) ◽  
pp. 941 ◽  
Author(s):  
Luana Priscila de Carvalho Pereira ◽  
Fábio Souto Almeida ◽  
André Barbosa Vargas ◽  
Marcel Santos de Araújo ◽  
Antônio José Mayhé-Nunes ◽  
...  
Keyword(s):  
Functional Groups ◽  
Functional Diversity ◽  
Taxonomic Diversity ◽  
Native Forest ◽  
Amazon Forest ◽  
Functional Richness ◽  
Significant Difference ◽  
Seasonal Analysis ◽  
Ant Diversity ◽  
Dry And Rainy Seasons

The present study aimed at assessing the effects of climate seasonality on poneromorph ants in the Brazilian Amazon, by studying variations in composition, richness, and taxonomic and functional diversity. The study was carried out in the Tapirapé-Aquiri National Forest, southeastern Pará State. We collected poneromorph ants in three areas of native forest with pitfall traps and sardine baits on the ground and vegetation, in two dry and rainy seasons. We collected 46 species of poneromorph ants, which belong to two subfamilies and eleven genera. The species composition, richness and taxonomic diversity did not vary significantly between seasons. There was no significant difference in the frequency of species of functional groups between dry and rainy seasons. There was no significant difference in the average richness and average diversity of functional groups between the dry and rainy seasons. In our study we found no seasonal differences in composition, taxonomic and functional richness and diversity of poneromorph ants in the Amazon, which is useful for future studies that aim at using those ants as bioindicators. In addition, the identification of the species made in the present study has special relevance as it contributes to advance the knowledge of poneromorph ant diversity in the Amazon.

scholarly journals The cryptic impacts of invasion: Functional homogenization of tropical ant communities by invasive fire ants

2019 ◽  
Author(s):  
Mark K. L. Wong ◽  
Benoit Guénard ◽  
Owen T. Lewis
Keyword(s):  
Functional Diversity ◽  
Taxonomic Diversity ◽  
Individual Species ◽  
Ecological Communities ◽  
Ant Communities ◽  
Invasive Insects ◽  
Tropical Grasslands ◽  
Functional Richness ◽  
Functional Identities ◽  
Functional Homogenization

AbstractInvasive insects represent major threats to ecosystems worldwide. Yet their effects on the functional dimension of biodiversity, measured as the diversity and distribution of traits, are overlooked. Such measures often determine the resilience of ecological communities and the ecosystem processes they modulate. The fire ant Solenopsis invicta is a highly problematic invasive species occurring on five continents. Its impacts on the taxonomic diversity of native ant communities have been studied but its impacts on their functional diversity are unknown. Comparing invaded and uninvaded plots in tropical grasslands of Hong Kong, we investigated how the presence of S. invicta affects the diversity and distribution of ant species and traits within and across communities, the functional identities of communities, and functionally unique species. We calculated the functional diversity of individual species, including the trait variation from intraspecific polymorphisms, and scaled up these values to calculate functional diversity at the community level. Invasion had only limited effects on species richness and functional richness, which were 13% and 8.5% lower in invaded communities respectively. In contrast, invasion had pronounced effects on taxonomic and functional composition due to turnover in species and trait values. Furthermore, invaded communities were functionally more homogeneous, displaying 23% less turnover and 56% more redundancy than uninvaded communities, as well as greater clustering and lower divergence in trait values. Invaded communities had fewer functionally-unique individuals and were characterized by ant species with narrower heads and bodies and shorter mandibles. Our results suggest that studies based only on taxonomic measures of diversity or indices describing trait variety risk underestimating the full ramifications of invasions. Investigating the diversity and distributions of traits at species, community and landscape levels can reveal the cryptic impacts of alien species which, despite causing little taxonomic change, may substantially modify the structure and functioning of ecological communities.

Temperature and vegetation complexity structure mixed-species flocks along a gradient of elevation in the tropical Andes

The Auk ◽  
2021 ◽  
Author(s):  
Flavia A Montaño-Centellas ◽  
Harrison H Jones
Keyword(s):  
Species Richness ◽  
Abiotic Stress ◽  
Environmental Gradients ◽  
Bird Community ◽  
Taxonomic Diversity ◽  
High Elevation ◽  
Tropical Andes ◽  
Mixed Species ◽  
Mixed Species Flocks ◽  
Species Flocks

Abstract Mixed-species flocks constitute community modules that can help test mechanisms driving changes to community composition across environmental gradients. Here, we examined elevational patterns of flock diversity (species richness, taxonomic diversity, species, and guild composition) and asked if these patterns were reflections of the full bird community at a given elevation (open-membership hypothesis), or if they were instead structured by environmental variables. We surveyed both the overall avian community and mixed-species flocks across an undisturbed elevational gradient (~1,350–3,550 m) in the Bolivian Andes. We then tested for the role of temperature (a surrogate for abiotic stress), resource diversity (arthropods, fruits), and foraging niche diversity (vegetation vertical complexity) in structuring these patterns. Patterns for the overall and flocking communities were similar, supporting our open-membership hypothesis that Andean flocks represent dynamic, unstructured aggregations. Membership openness and the resulting flock composition, however, also varied with elevation in response to temperature and vegetation complexity. We found a mid-elevation peak in flock species richness, size, and Shannon’s diversity at ~2,300 m. The transition of flocking behavior toward a more open-membership system at this elevation may explain a similar peak in the proportion of insectivores joining flocks. At high elevations, increasing abiotic stress and decreasing fruit diversity led more generalist, gregarious tanagers (Thraupidae) to join flocks, resulting in larger yet more even flocks alongside a loss of vegetation structure. At lower elevations, flock species richness increased with greater vegetation complexity, but a greater diversity of foraging niches resulted in flocks that were more segregated into separate canopy and understory sub-types. This segregation likely results from increased costs of interspecific competition and activity matching (i.e., constraints on movement and foraging rate) for insectivores. Mid-elevation flocks (~2,300 m) seemed, therefore, to benefit from both the open-membership composition of high-elevation flocks and the high vegetation complexity of mid- and low-elevation forests.

scholarly journals Ecological Divergence of a Novel Group of Chloroflexus Strains along a Geothermal Gradient

2012 ◽  
Vol 79 (4) ◽  
pp. 1353-1358 ◽  
Author(s):  
Michael L. Weltzer ◽  
Scott R. Miller
Keyword(s):  
16S Rrna ◽  
Carbon Fixation ◽  
Hot Spring ◽  
Environmental Gradients ◽  
Geothermal Gradient ◽  
Geothermal Systems ◽  
Local Conditions ◽  
Content Type ◽  
Thermal Niche ◽  
Coa Reductase

ABSTRACTEnvironmental gradients are expected to promote the diversification and coexistence of ecological specialists adapted to local conditions. Consistent with this view, genera of phototrophic microorganisms in alkaline geothermal systems generally appear to consist of anciently divergent populations which have specialized on different temperature habitats. At White Creek (Lower Geyser Basin, Yellowstone National Park), however, a novel, 16S rRNA-defined lineage of the filamentous anoxygenic phototrophChloroflexus(OTU 10, phylumChloroflexi) occupies a much wider thermal niche than other 16S rRNA-defined groups of phototrophic bacteria. This suggests thatChloroflexusOTU 10 is either an ecological generalist or, alternatively, a group of cryptic thermal specialists which have recently diverged. To distinguish between these alternatives, we first isolated laboratory strains ofChloroflexusOTU 10 from along the White Creek temperature gradient. These strains are identical for partial gene sequences encoding the 16S rRNA and malonyl coenzyme A (CoA) reductase. However, strains isolated from upstream and downstream samples could be distinguished based on sequence variation atpcs, which encodes the propionyl-CoA synthase of the 3-hydroxypropionate pathway of carbon fixation used by the genusChloroflexus. We next demonstrated that strains have diverged in temperature range for growth. Specifically, we obtained evidence for a positive correlation between thermal niche breadth and temperature optimum, with strains isolated from lower temperatures exhibiting greater thermal specialization than the most thermotolerant strain. The study has implications for our understanding of both the process of niche diversification of microorganisms and how diversity is organized in these hot spring communities.

scholarly journals Effects of area and available energy on fish assemblages of tropical streams

2017 ◽  
Vol 68 (4) ◽  
pp. 772 ◽  
Author(s):  
Bruno Bastos Gonçalves ◽  
Francisco Leonardo Tejerina-Garro ◽  
Rodrigo Assis de Carvalho
Keyword(s):  
River Basin ◽  
Fish Assemblages ◽  
Regional Scale ◽  
Drainage Area ◽  
Taxonomic Richness ◽  
Local Conditions ◽  
Available Energy ◽  
Functional Richness ◽  
Araguaia River ◽  
Species Area

A central issue in fish community ecology is to understand how the size of the drainage area and the available energy influence fish species diversity and their spatial distribution. In the present study, we tested whether the species–area relationship (represented by drainage area) and species–energy association (represented by algal biomass and organic matter) drive taxonomic and functional richness in a regional scale. The results indicated that fish assemblages of the two tropical neighbouring basins sampled responded differently to the size of drainage area. Whereas taxonomic richness was influenced by the size of the drainage area in Tocantins River basin streams, it was not affected in Araguaia River basin streams. Both taxonomic richness and functional richness of the fish assemblages were affected by available energy in the system. A possible explanation for these different responses is related to local conditions, such as the percentage of natural vegetation cover encountered in each basin.

Effect of tropical rainfall in structuring the macrobenthic community of Mandovi estuary, west coast of India

2013 ◽  
Vol 93 (7) ◽  
pp. 1727-1738 ◽  
Author(s):  
Udaykumar V. Gaonkar ◽  
Sanitha K. Sivadas ◽  
Baban S. Ingole
Keyword(s):  
West Coast ◽  
Temporal Dynamics ◽  
Environmental Parameters ◽  
Macrobenthic Community ◽  
Tropical Estuary ◽  
West Coast Of India ◽  
Run Off ◽  
Macrobenthic Assemblages ◽  
Macrofaunal Community ◽  
Mandovi Estuary

Macrofaunal community structure is determined by a number of environmental variables. The riverine run-off during the monsoon brings about drastic changes in the physico-chemical parameters of a tropical estuary. The aim of the present study was to investigate the influence of rainfall in structuring the benthic macrofaunal community of a tropical estuary. The temporal dynamics of the macrobenthic community in the monsoon dominated Mandovi estuary (central west coast of India) was studied fortnightly from June 2007 to June 2009. A fixed location, downstream of the Madovi river, was sampled for benthic and water parameters. Ten replicates were collected during each sampling date using a Van Veen grab (0.04 m2). The macrofaunal abundance showed temporal fluctuation. The multivariate analysis showed the clustering of the samples linked to the environmental parameters (CCA and LINKTREE). The temporal variation observed in the macrofaunal abundance was basically due to changes in abundance of the dominant species. The variation in macrofaunal abundance was brought about by the recruitment and settling of re-suspended adults. It can be concluded that the macrofaunal structuring is influenced by temporal changes in the environment associated with the annual monsoon rainfall. Hence climate induced changes in the monsoonal pattern may affect the macrobenthic assemblages of tropical estuaries.

scholarly journals Limits to adaptation along environmental gradients

2014 ◽  
Author(s):  
Jitka Polechová ◽  
Nick Barton
Keyword(s):  
Gene Flow ◽  
Genetic Drift ◽  
Environmental Gradients ◽  
Single Species ◽  
Local Conditions ◽  
Deterministic Theory ◽  
Range Margin ◽  
Abrupt Changes ◽  
Analytical Tools ◽  
Range Fragmentation

Why do species not adapt to ever-wider ranges of conditions, gradually expanding their ecological niche and geographic range? Gene flow across environments has two conflicting effects: while it increases genetic variation, which is a prerequisite for adaptation, gene flow may swamp adaptation to local conditions. In 1956, Haldane proposed that when the environment varies across space, ?swamping? by gene flow creates a positive feedback between low population size and maladaptation, leading to a sharp range margin. Yet, current deterministic theory shows that when variance can evolve, there is no such limit. Using simple analytical tools and simulations, we show that genetic drift can generate a sharp margin to a species' range, by reducing genetic variance below the level needed for adaptation to spatially variable conditions. Aided by separation of ecological and evolutionary time scales, the identified effective dimensionless parameters reveal a simple threshold that predicts when adaptation at the range margin fails. Two observable parameters determine the threshold: i) the effective environmental gradient, which can be measured by the loss of fitness due to dispersal to a different environment, and ii) the efficacy of selection relative to genetic drift. The theory predicts sharp range margins even in the absence of abrupt changes in the environment. Furthermore, it implies that gradual worsening of conditions across a species' habitat may lead to a sudden range fragmentation, when adaptation to a wide span of conditions within a single species becomes impossible.

scholarly journals Thermal Comfort Assessment and Heat-Related Illnesses among Sellers in Periodic Local Markets: A Case Study in Hot and Dry Climate of Iran

2021 ◽  
Author(s):  
Hoda Rahimifard ◽  
Hamidreza Heidari ◽  
Abolfazl Mohamadbeigi ◽  
Ahmad Soltanzadeh ◽  
Mohsen Mahdinia ◽  
...  
Keyword(s):  
Thermal Comfort ◽  
Environmental Parameters ◽  
Thermal Conditions ◽  
Tympanic Temperature ◽  
Thermal Indices ◽  
Local Conditions ◽  
Environmental Indices ◽  
Local Markets ◽  
Hot Climate ◽  
Globe Temperature

Background:This study aims to evaluate the thermal conditions of periodic local markets and determine the thermal comfort and sensation of sellers, as well as the prevalence of heat-related diseases in the hot and dry climate of Iran. Methods:In this study, thermal comfort and sensation of 330 sellers from periodic markets in Qom city, a dry and hot climate in Iran, were evaluated. Measurements were performed for 15 days, from July 16 to August 1. To assess environmental thermal condition, wet bulb globe temperature (WBGT) index and discomfort index (DI) were determined, and participants' tympanic temperature was determined to consistency assessment with thermal indices. Finally, the effects of environmental, personal, and working conditions on the prevalence of heat-related diseases among sellers were determined. Results:The environmental indices, including DI and WBGT index, had the most association with heat-related illnesses and tympanic temperature (P<0.05). The sellers perceived the environmental conditions as warm to hot after 1:00 pm. Besides, they expressed an uncomfortable or very uncomfortable situation after 12:00 pm. The findings showed that environmental parameters play a more important role in the prevalence of heat-related diseases and heat strain than individual and occupational factors. Conclusion:The sellers may be at risk of heat stress in outdoor markets in nearly half of the workday in the summer months. Therefore, it is very important that these people receive the necessary training in the prevention of heat illness in order to take appropriate protective measures in accordance with local conditions.

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