scholarly journals Ecological Gradients (West-East) and Vegetation of the Central Great Caucasus

Bocconea ◽  
2021 ◽  
Vol 29 ◽  
Keyword(s):  
Ecological Gradients

scholarly journals Local adaptation stops where ecological gradients steepen or are interrupted

2019 ◽  
Vol 12 (7) ◽  
pp. 1449-1462 ◽  
Author(s):  
Jon R. Bridle ◽  
Masakado Kawata ◽  
Roger K. Butlin
Keyword(s):  
Local Adaptation ◽  
Ecological Gradients

scholarly journals Testing the potential of pollen assemblages to capture composition, diversity and ecological gradients of surrounding vegetation in two biogeographical regions of southeastern Europe

2021 ◽  
Author(s):  
Maria Papadopoulou ◽  
Ioannis Tsiripidis ◽  
Sampson Panajiotidis ◽  
Georgios Fotiadis ◽  
Daniel Veres ◽  
...  
Keyword(s):  
Vegetation Structure ◽  
Diversity Indices ◽  
Life Forms ◽  
Ecological Gradients ◽  
Vegetation Diversity ◽  
North Central ◽  
Plant Life Forms ◽  
Pollen Diagrams ◽  
Biogeographical Regions ◽  
Species Specific

AbstractDue to the complex relationship between pollen and vegetation, it is not yet clear how pollen diagrams may be interpreted with respect to changes in floristic diversity and only a few studies have hitherto investigated this problem. We compare pollen assemblages from moss samples in two southeastern European forests with the surrounding vegetation to investigate (a) their compositional similarity, (b) the association between their diversity characteristics in both terms of richness and evenness, and (c) the correspondence of the main ecological gradients that can be revealed by them. Two biogeographical regions with different vegetation characteristics, the Pieria mountains (north central Greece) and the slopes of Ciomadul volcano (eastern Romania), were chosen as divergent examples of floristic regions, vegetation structure and landscape openness. Pollen assemblages are efficient in capturing the presence or absence, rather than the abundance in distribution of plants in the surrounding area and this bias increases along with landscape openness and vegetation diversity, which is higher in the Pieria mountains. Pollen assemblages and vegetation correlate better in terms of richness, that is, low order diversity indices. Relatively high correlation, in terms of evenness, could be potentially found in homogenous and species poor ecosystems as for Ciomadul. Composition and diversity of woody, rather than herb, vegetation is better reflected in pollen assemblages of both areas, especially for Pieria where a direct comparison of the two components was feasible, although this depends on the species-specific pollen production and dispersal, the openness of landscape and the overall diversity of vegetation. Gradients revealed by pollen assemblages are highly and significantly correlated with those existing in vegetation. Pollen assemblages may represent the vegetation well in terms of composition, diversity (mainly richness) and ecological gradients, but this potential depends on land use, vegetation structure, biogeographical factors and plant life forms.

scholarly journals Effects of Ecological Gradients on Tropical Avian Hemoparasites

2020 ◽  
pp. 349-377
Author(s):  
Leonardo Chapa-Vargas ◽  
Nubia E. Matta ◽  
Santiago Merino
Keyword(s):  
Ecological Gradients

scholarly journals Contributions to the research of ecological gradients in the treatment of floristic data (Oran, Algeria)

2020 ◽  
Vol 11 (2) ◽  
pp. 383-388
Author(s):  
Mustapha Ainad Tabet ◽  
Noury Benabadji ◽  
Abdessamad Merzouk ◽  
Halima Benmoussat
Keyword(s):  
Ecological Gradients ◽  
Floristic Data

scholarly journals Avian succession along ecological gradients: Insight from species-poor and species-rich communities of Sylvia warblers

2011 ◽  
Vol 57 (3) ◽  
pp. 307-317 ◽  
Author(s):  
Alban Guillaumet ◽  
Roger Prodon
Keyword(s):  
Interspecific Competition ◽  
Species Turnover ◽  
Predictive Ability ◽  
Distribution Model ◽  
Joint Analysis ◽  
Data Sets ◽  
Ecological Gradients ◽  
Distribution Models ◽  
Ecological Release ◽  
Low Diversity

Abstract The mechanisms responsible for species replacement during ecological successions is a long-standing and open debate. In this study, we examined the distribution of the Sardinian warbler Sylvia melanocephala along two grassland-to-forest gradients, one in a high-diversity area (Albera-Aspres chain in Catalonia: eight Sylvia warbler species) and one in a low-diversity area (Mount Hymittos in Greece: four species). In Catalonia, distribution models suggested that the apparent exclusion of S. melanocephala from the open and forest ends of the gradient may be explained entirely by the preference of S. melanocephala for mid-successional shrublands. However, a joint analysis of both data sets revealed that: 1) S. melanocephala was more evenly distributed along the vegetation gradient in Greece, suggesting ecological release in the low-diversity area; and 2) a distribution model assuming interspecific competition (based on the distribution of Sylvia species showing a negative co-occurrence pattern with S. melanocephala) had a significantly higher predictive ability than a distribution model based on habitat variables alone. Our study supports the view that species turnover along ecological gradients generally results from a combination of intrinsic preferences and interspecific competition.

An abundance- and morphology-based similarity index

Paleobiology ◽  
2021 ◽  
pp. 1-18
Author(s):  
Daniel G. Dick ◽  
Marc Laflamme
Keyword(s):  
River Flow ◽  
Similarity Index ◽  
Ecological Gradients ◽  
Jaccard Similarity ◽  
Real World Data ◽  
Large Component ◽  
Morphological Gradient ◽  
Random Samples ◽  
Similarity Indices ◽  
General Method

Abstract Classic similarity indices measure community resemblance in terms of incidence (the number of shared species) and abundance (the extent to which the shared species are an equivalently large component of the ecosystem). Here we describe a general method for increasing the amount of information contained in the output of these indices and describe a new “soft” ecological similarity measure (here called “soft Chao-Jaccard similarity”). The new measure quantifies community resemblance in terms of shared species, while accounting for intraspecific variation in abundance and morphology between samples. We demonstrate how our proposed measure can reconstruct short ecological gradients using random samples of taxa, recognizing patterns that are completely missed by classic measures of similarity. To demonstrate the utility of our new index, we reconstruct a morphological gradient driven by river flow velocity using random samples drawn from simulated and real-world data. Results suggest that the new index can be used to recognize complex short ecological gradients in settings where only information about specimens is available. We include open-source R code for calculating the proposed index.

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