scholarly journals Microalgae colonization of different microplastic polymers in experimental mesocosms across an environmental gradient

2021 ◽  
Author(s):  
Veronica Nava ◽  
Miguel Graça Matias ◽  
Andreu Castillo‐Escrivà ◽  
Beata Messyasz ◽  
Barbara Leoni
Keyword(s):  
Environmental Gradient ◽  
Experimental Mesocosms

scholarly journals Fish community shifts along a strong fluvial environmental gradient revealed by eDNA metabarcoding

2021 ◽  
Author(s):  
Erik García‐Machado ◽  
Martin Laporte ◽  
Eric Normandeau ◽  
Cecilia Hernández ◽  
Guillaume Côté ◽  
...  
Keyword(s):  
Fish Community ◽  
Environmental Gradient ◽  
Community Shifts

scholarly journals Adaptive Divergence under Gene Flow along an Environmental Gradient in Two Coexisting Stickleback Species

Genes ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 435
Author(s):  
Thijs M. P. Bal ◽  
Alejandro Llanos-Garrido ◽  
Anurag Chaturvedi ◽  
Io Verdonck ◽  
Bart Hellemans ◽  
...  
Keyword(s):  
Gene Flow ◽  
Brackish Water ◽  
Environmental Gradient ◽  
Spatial Scales ◽  
Morphological Differentiation ◽  
Genotyping By Sequencing ◽  
Adaptive Divergence ◽  
Linkage Groups ◽  
Closely Related Species ◽  
Genomic Patterns

There is a general and solid theoretical framework to explain how the interplay between natural selection and gene flow affects local adaptation. Yet, to what extent coexisting closely related species evolve collectively or show distinctive evolutionary responses remains a fundamental question. To address this, we studied the population genetic structure and morphological differentiation of sympatric three-spined and nine-spined stickleback. We conducted genotyping-by-sequencing and morphological trait characterisation using 24 individuals of each species from four lowland brackish water (LBW), four lowland freshwater (LFW) and three upland freshwater (UFW) sites in Belgium and the Netherlands. This combination of sites allowed us to contrast populations from isolated but environmentally similar locations (LFW vs. UFW), isolated but environmentally heterogeneous locations (LBW vs. UFW), and well-connected but environmentally heterogenous locations (LBW vs. LFW). Overall, both species showed comparable levels of genetic diversity and neutral genetic differentiation. However, for all three spatial scales, signatures of morphological and genomic adaptive divergence were substantially stronger among populations of the three-spined stickleback than among populations of the nine-spined stickleback. Furthermore, most outlier SNPs in the two species were associated with local freshwater sites. The few outlier SNPs that were associated with the split between brackish water and freshwater populations were located on one linkage group in three-spined stickleback and two linkage groups in nine-spined stickleback. We conclude that while both species show congruent evolutionary and genomic patterns of divergent selection, both species differ in the magnitude of their response to selection regardless of the geographical and environmental context.

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.

Genotype by environment interaction for yearling weight in Nellore cattle applying reaction norms models

2018 ◽  
Vol 58 (11) ◽  
pp. 1996
Author(s):  
S. Ribeiro ◽  
J. P. Eler ◽  
V. B. Pedrosa ◽  
G. J. M. Rosa ◽  
J. B. S. Ferraz ◽  
...  
Keyword(s):  
Genetic Correlation ◽  
Environmental Gradient ◽  
Genotype By Environment Interaction ◽  
Reaction Norms ◽  
Breeding Value ◽  
Environment Interaction ◽  
Genotype By Environment ◽  
Genotype Environment Interaction ◽  
Nellore Cattle ◽  
Gradient Variation

In the present study, a possible existence of genotype × environment interaction was verified for yearling weight in Nellore cattle, utilising a reaction norms model. Therefore, possible changes in the breeding value were evaluated for 46 032 animals, from three distinct herds, according to the environmental gradient variation of the different contemporary groups. Under a Bayesian approach, analyses were carried out utilising INTERGEN software resulting in solutions of contemporary groups dispersed in the environmental gradient from –90 to +100 kg. The estimates of heritability coefficients ranged from 0.19 to 0.63 through the environmental gradient and the genetic correlation between intercept and slope of the reaction norms was 0.76. The genetic correlation considering all animals of the herds in the environmental gradient ranged from 0.83 to 1.0, and the correlation between breeding values of bulls in different environments ranged from 0.79 to 1.0. The results showed no effect of genotype × environment interaction on yearling weight in the herds of this study. However, it is important to verify a possible influence of the genotype × environment in the genetic evaluation of beef cattle, as different environments might cause interference in gene expression and consequently difference in phenotypic response.

Competitive and facilitative interactions within and between two species of coastal dune perennials

2003 ◽  
Vol 81 (4) ◽  
pp. 330-337 ◽  
Author(s):  
Steven J Franks
Keyword(s):  
Environmental Gradient ◽  
Coastal Dune ◽  
Positive Interactions ◽  
Substantial Evidence ◽  
Species Identity ◽  
Uniola Paniculata ◽  
Disturbed Zone ◽  
As Stress ◽  
Facilitative Interactions ◽  
Target Plant

While there is substantial evidence for facilitation, the effects of such factors as stress and species identity on positive interactions remain controversial. At two coastal dune sites, I tested the hypotheses that facilitative interactions increase with increasing stress and disturbance along an environmental gradient and that facilitative interactions are stronger among heterospecific than among conspecific individuals. I transplanted Uniola paniculata and Iva imbricata plants into plots along with four conspecific neighbors, four heterospecific neighbors, or no neighbors across an environmental gradient. Neighbors increased target plant survival, suggesting facilitation, but biomass of targets was reduced by the presence of neighbors, suggesting competition. Unexpectedly, competition was greatest in the purportedly most stressful and disturbed zone. In this study, the outcome of neighbor interactions differed for biomass and survival and depended on position along the environmental gradient, but was independent of neighbor identity.Key words: competition, disturbance, facilitation, Iva imbricata, stress, Uniola paniculata.

Basalt weathering and pedogenesis across an environmental gradient in the southern Cascade Range, California, USA

Geoderma ◽  
2010 ◽  
Vol 154 (3-4) ◽  
pp. 473-485 ◽  
Author(s):  
Craig Rasmussen ◽  
Randy A. Dahlgren ◽  
Randal J. Southard
Keyword(s):  
Environmental Gradient ◽  
Cascade Range ◽  
Basalt Weathering

Color lightness of velvet ants (Hymenoptera: Mutillidae) follows an environmental gradient

2021 ◽  
pp. 103030
Author(s):  
Vinicius Marques Lopez ◽  
Thaína Aparecida Azevedo Tosta ◽  
Guilherme Gonzaga da Silva ◽  
Pedro Reck Bartholomay ◽  
Kevin Andrew Williams ◽  
...  
Keyword(s):  
Environmental Gradient
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