Interactions between transplants of Phragmites australis and Juncus acutus in Mediterranean coastal marshes: The modulating role of environmental gradients

2015 ◽  
Vol 124 ◽  
pp. 29-38 ◽  
Author(s):  
Efrem Batriu ◽  
Josep M. Ninot ◽  
Joan Pino
Keyword(s):  
Phragmites Australis ◽  
Environmental Gradients ◽  
Coastal Marshes ◽  
Juncus Acutus

Dryland legumes: perspectives and problems

2003 ◽  
Vol 11 ◽  
pp. 27-36
Author(s):  
D. Scott
Keyword(s):  
Root Nodule ◽  
Fine Root ◽  
Animal Feed ◽  
Environmental Gradients ◽  
N Fixation ◽  
Indigenous Species ◽  
Nodule Bacteria ◽  
Pastoral Systems ◽  
Fertility Gradient

The different perspectives or concepts involved in developing legumes for dryland pastoral systems is commented on in relation to: N-fixation versus animal feed; root nodule bacteria requirements; large introduced legume flora compared with indigenous; species niche in relation to environmental gradients of moisture, temperature, fertility, and grazing; species adaptation along the decreasing fertility gradient from fine-root nutrient scavenging grasses, N-fixers, mycorrhiza, and proteoid roots; interaction of N- fixation with soil organic matter; establishment; determinants of pastures legume composition; and the possible role of allelopathy. Key words: dryland, environmental gradients, legumes, N-fixation, pasture composition

Shell variations in the gastropod, Monodonta labio, in the North-western Pacific: the important role of temperature in the evolution process

2019 ◽  
Vol 99 (7) ◽  
pp. 1591-1599
Author(s):  
Dan Zhao ◽  
Ling-Feng Kong ◽  
Takenori Sasaki ◽  
Qi Li
Keyword(s):  
Environmental Gradients ◽  
Ecological Factors ◽  
Local Maximum ◽  
Morphological Diversity ◽  
Shell Shape ◽  
Shape Variation ◽  
Genetic Structuring ◽  
Morphological Variations ◽  
China Sea

AbstractMolluscan shells showing phenotypic variations are ideal models for studying evolution and plasticity. In north-eastern Asia, genetic and morphological diversity of the gastropod, Monodonta labio, were assumed to be influenced by both palaeoclimatic changes and current ecological factors. In this study, we examined spatial variations in shell shape of M. labio using general measurement and geometric morphometric analysis. We also investigated whether shell shape variation is best explained by environmental gradients or by genetic structuring, based on our prior molecular phylogeographic study. Two common morphological forms were observed among Chinese populations and in the adjacent Asian areas. Both the analyses revealed separation patterns in morphological variations of shell shape among the clades and populations. Environmental modelling analysis showed a significant correlation between shape variations and local maximum temperatures of the warmest month, indicating the role of natural selection in the evolution of this species. Data obtained in this study, combined with the cytochrome oxidase subunit I (COI) molecular phylogenetic data from the prior study, showed that morphological variations in M. labio were constrained by both local adaptation and phenotypic plasticity. We hypothesized that geographic separation by the Dongshan Landbridge was the first step towards its diversification, and that the temperature gradient between the East China Sea and South China Sea probably was the selective force driving the divergence of its morphological variations.

scholarly journals Range-wide spatial mapping reveals convergent character displacement of bird song

2019 ◽  
Vol 286 (1902) ◽  
pp. 20190443 ◽  
Author(s):  
Alexander N. G. Kirschel ◽  
Nathalie Seddon ◽  
Joseph A. Tobias
Keyword(s):  
Spatial Patterns ◽  
Evolutionary Biology ◽  
Environmental Gradients ◽  
Empirical Studies ◽  
Remote Sensing Data ◽  
Character Displacement ◽  
Similar Species ◽  
Interspecific Territoriality ◽  
Coexisting Species

A long-held view in evolutionary biology is that character displacement generates divergent phenotypes in closely related coexisting species to avoid the costs of hybridization or ecological competition, whereas an alternative possibility is that signals of dominance or aggression may instead converge to facilitate coexistence among ecological competitors. Although this counterintuitive process—termed convergent agonistic character displacement—is supported by recent theoretical and empirical studies, the extent to which it drives spatial patterns of trait evolution at continental scales remains unclear. By modelling the variation in song structure of two ecologically similar species of Hypocnemis antbird across western Amazonia, we show that their territorial signals converge such that trait similarity peaks in the sympatric zone, where intense interspecific territoriality between these taxa has previously been demonstrated. We also use remote sensing data to show that signal convergence is not explained by environmental gradients and is thus unlikely to evolve by sensory drive (i.e. acoustic adaptation to the sound transmission properties of habitats). Our results suggest that agonistic character displacement driven by interspecific competition can generate spatial patterns opposite to those predicted by classic character displacement theory, and highlight the potential role of social selection in shaping geographical variation in signal phenotypes of ecological competitors.

scholarly journals Trophic Features, Benthic Recovery, and Dominance of the Invasive Mytilopsis Sallei in the Yundang Lagoon (Xiamen, China) Following Long-Term Restoration

Water ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1692 ◽  
Author(s):  
Paolo Magni ◽  
Serena Como ◽  
Maria Flavia Gravina ◽  
Donghui Guo ◽  
Chao Li ◽  
...  
Keyword(s):  
Land Reclamation ◽  
Environmental Gradients ◽  
Oxygen Demand ◽  
Current Status ◽  
Pest Species ◽  
Future Evolution ◽  
Mytilopsis Sallei ◽  
Biological Tool

A comprehensive set of physicochemical variables in near-bottom water and surface sediments, as well as the soft-bottom macrozoobenthic assemblages were investigated at six sites across the Yundang Lagoon (Southeast China) in November 2012. This lagoon was severely damaged in the 1970s due to domestic and industrial pollution and land reclamation and underwent a massive restoration effort over the past 30 years. Our objectives were to: (1) assess the current trophic and environmental condition of the lagoon; (2) investigate the pattern of spatial variation in the macrozoobenthic assemblages; and (3) assess the benthic recovery in relation to the main environmental gradients and the presence of invasive alien species. Nutrient, chlorophyll-a, biological oxygen demand (BOD5), chemical oxygen demand (CODMn), and total organic carbon (TOC) concentrations were lower than those reported in previous decades, yet organically-enriched conditions occurred at an inner site. From azoic conditions in the 1980s and a few benthic species reported prior to this study, we found a significant increase in benthic diversity with 43 species heterogeneously distributed across the lagoon. The invasive bivalve Mytilopsis sallei was the dominant species, which was associated with the richest benthic assemblage. However, M. sallei is a pest species, and its spatiotemporal distribution should be carefully monitored. These results highlight the central role of the macrozoobenthos in providing important ecological information on the current status of the Yundang Lagoon and as an effective biological tool to follow the recovery’s progress and the future evolution of this highly valued ecosystem.

scholarly journals The Effect of Artificial Mowing on the Competition of Phragmites australis and Spartina alterniflora in the Yangtze Estuary

Scientifica ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Yue Yuan ◽  
Chao Zhang ◽  
Dezhi Li
Keyword(s):  
Spartina Alterniflora ◽  
Phragmites Australis ◽  
Native Species ◽  
Interspecific Interactions ◽  
Interaction Strength ◽  
Yangtze Estuary ◽  
The Yangtze Estuary ◽  
Neighbor Effect ◽  
Index Effect

Spartina alterniflora Loisel. is one of the most invasive species in the world. However, little is known about the role of artificial mowing in its invasiveness and competiveness. In this work, we studied the effect of mowing on its interspecific interactions with native species Phragmites australis (Cav.) Trin ex Steud of the Yangtze Estuary, China. We calculated their relative neighbor effect (RNE) index, effect of relative crowding (Dr) index, and interaction strength (I) index. The results showed that the RNE of Phragmites australis and Spartina alterniflora was 0.354 and 0.619, respectively, and they have competitive interactions. The mowing treatments can significantly influence the RNE of Phragmites australis and Spartina alterniflora on each other. Concretely, the RNE of Spartina alterniflora in the removal treatments was significantly higher than the value in the controls. But the RNE of Phragmites australis in the removal treatments was significantly lower than the value in the controls. Meanwhile, Dr of the two species on the targets was higher in the removal treatments than that in the controls, and the opposite was for I. We concluded that artificial mowing could promote the invasion of Spartina alterniflora by increasing its competitive performance compared with native species.

Functional Role of Bacteria from Invasive Phragmites australis in Promotion of Host Growth

2016 ◽  
Vol 72 (2) ◽  
pp. 407-417 ◽  
Author(s):  
M. A. Soares ◽  
H-Y. Li ◽  
K. P. Kowalski ◽  
M. Bergen ◽  
M. S. Torres ◽  
...  
Keyword(s):  
Phragmites Australis ◽  
Functional Role ◽  
Host Growth

Stress tolerance mechanisms in Juncus: responses to salinity and drought in three Juncus species adapted to different natural environments

2016 ◽  
Vol 43 (10) ◽  
pp. 949 ◽  
Author(s):  
Mohamad Al Hassan ◽  
María del Pilar López-Gresa ◽  
Monica Boscaiu ◽  
Oscar Vicente
Keyword(s):  
Salt Tolerance ◽  
Stress Tolerance ◽  
Sugar Content ◽  
Natural Environments ◽  
Tolerance Mechanisms ◽  
Juncus Acutus ◽  
Osmotic Balance ◽  
Ion Contents ◽  
Response To Water

Comparative studies on the responses to salinity and drought were carried out in three Juncus species, two halophytes (Juncus maritimus Lam. and Juncus acutus L.) and one more salt-sensitive (Juncus articulatus L.). Salt tolerance in Juncus depends on the inhibition of transport of toxic ions to the aerial part. In the three taxa studied Na+ and Cl– accumulated to the same extent in the roots of salt treated plants; however, ion contents were lower in the shoots and correlated with the relative salt sensitivity of the species, with the lowest levels measured in the halophytes. Activation of K+ transport at high salt concentration could also contribute to salt tolerance in the halophytes. Maintenance of cellular osmotic balance is mostly based on the accumulation of sucrose in the three species. Yet, neither the relative salt-induced increase in sugar content nor the absolute concentrations reached can explain the observed differences in salt tolerance. In contrast, proline increased significantly in the presence of salt only in the salt-tolerant J. maritimus and J. acutus, but not in J. articulatus. Similar patterns of osmolyte accumulation were observed in response to water stress, supporting a functional role of proline in stress tolerance mechanisms in Juncus.

scholarly journals Ecotones: Marginal or central areas of transition?

2006 ◽  
Vol 52 (1) ◽  
pp. 29-53 ◽  
Author(s):  
Salit Kark ◽  
Berndt J. van Rensburg
Keyword(s):  
Environmental Gradients ◽  
Spatial Scales ◽  
Small Scale ◽  
Biodiversity Hotspots ◽  
Ecological Communities ◽  
Marginal Populations ◽  
Multiple Spatial Scales ◽  
Scientific Attention

Areas of environmental transition, where ecological communities coincide, are sometimes termed ecotones. These regions often correspond with sharp environmental gradients. Ecotones occur at multiple spatial scales, ranging from transitions between biomes to local small-scale transitions. In recent years ecotones have received increasing scientific attention after being neglected for years, as studies historically often focused on distinct communities. However, it is still debatable whether these transitional regions are speciation and biodiversity hotspots that deserve special conservation interest or are actually areas that hold marginal populations that depend on other parts of the range for the maintenance of their biodiversity and therefore should not deserve primary investment. This paper discusses some of the recent advancements in our understanding of the role of ecotones in ecology, evolution, and conservation.

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