نتایج جستجو برای: altitudinal gradient

تعداد نتایج: 127976  

2007
Federico Escobar Jorge M. Lobo Gonzalo Halffter

Aims The fauna of mountains and their surrounding regions are likely to be influenced principally by two biological processes: horizontal colonization along similar altitudinal levels by elements originating from lineages inhabiting higher latitudes; and vertical colonization by lineages from the same latitude, but at lower altitudes. We examine whether the expected patterns derived from the la...

2017
Lucas Neves Perillo Frederico de Siqueira Neves Yasmine Antonini Rogério Parentoni Martins

Climate conditions tend to differ along an altitudinal gradient, resulting in some species groups' patterns of lower species richness with increasing altitude. While this pattern is well understood for tropical mountains, studies investigating possible determinants of variation in beta-diversity at its different altitudes are scarce. We sampled bee and wasp communities (Hymenoptera: Aculeata) a...

Journal: :American journal of botany 2016
Luis Abdala-Roberts Sergio Rasmann Jorge C Berny-Mier Y Terán Felisa Covelo Gaétan Glauser Xoaquín Moreira

PREMISE OF THE STUDY It is generally thought that herbivore pressure is higher at lower elevations where climate is warmer and less seasonal, and that this has led to higher levels of plant defense investment at low elevations. However, the generality of this expectation has been called into question by recent studies. METHODS We tested for altitudinal gradients in insect leaf damage, plant d...

Journal: :Genetics 2007
Verónica V Lia Viviana A Confalonieri Lidia Poggio

Cytogenetic analysis of maize landraces from northwestern Argentina has revealed an altitudinal cline in the mean number of B chromosomes (B's) per plant, with cultivars growing at higher altitudes exhibiting a higher number of B's. Altitudinal and longitudinal clines are frequently interpreted as evidence of selection, however, they can also be produced by the interplay between drift and spati...

2013
Shou-Qin Sun Yan-Hong Wu Gen-Xu Wang Jun Zhou Dong Yu Hai-Jian Bing Ji Luo

An investigation of terrestrial bryophyte species diversity and community structure along an altitudinal gradient from 2,001 to 4,221 m a.s.l. in Gongga Mountain in Sichuan, China was carried out in June 2010. Factors which might affect bryophyte species composition and diversity, including climate, elevation, slope, depth of litter, vegetation type, soil pH and soil Eh, were examined to unders...

2016
Cássio Alencar Nunes Rodrigo Fagundes Braga José Eugênio Cortes Figueira Frederico de Siqueira Neves G. Wilson Fernandes

Mountains provide an interesting context in which to study the many facets of biodiversity in response to macroclimate, since environmental conditions change rapidly due to elevation. Although the decrease in biodiversity with increasing elevation is generally accepted, our understanding of the variation of functional diversity along altitudinal gradients is still poorly known. The partitioning...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2002
Gary R Graves Christopher S Romanek Alejandro Rodriguez Navarro

Stable isotope analysis is widely promoted as a practical method for tracing the geographic origins of migratory birds. However, the extent to which geospatial patterns of isotope ratios in avian tissues are influenced by age-specific, altitudinal, and temporal factors remains largely unexplored. We measured carbon ((13)C/(12)C) and nitrogen ((15)N/(14)N) isotope ratios in feathers of black-thr...

Journal: :Revista de biologia tropical 2012
Lionel Hernández Nelda Dezzeo Elio Sanoja Leandro Salazar Hernán Castellanos

There have been several ecological studies in forests of the Guayana Shield, but so far none had examined the changes in structure and composition of evergreen forests with altitude. This study describes and analyzes the structure, species composition and soil characteristics of forest stands at different altitudinal zones in Southeastern Venezuelan Guayana, in order to explain the patterns and...

2017
Anna M. Lewandowska-Sabat Siri Fjellheim Jorunn E. Olsen Odd A. Rognli

Adaptation of plants to local conditions that vary substantially within their geographic range is essential for seasonal timing of flowering, a major determinant of plant reproductive success. This study investigates photoperiodic responses in natural populations of Arabidopsis thaliana from high northern latitudes and their significance for local adaptation. Thirty lineages from ten local A. t...

2012
Vít PENÍŽEK Tereza ZÁDOROVÁ

Mountainous areas represent regions with specific soil cover pattern that is naturally given by an altitudinal gradient. The objective of our study was to describe the soil cover development on the altitudinal gradient under changed environment given by man-planted vegetation and acidification. The studied area is characterized by spruce monoculture planting that replaced the original broadleaf...

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