نتایج جستجو برای: ecological factors
تعداد نتایج: 1163995 فیلتر نتایج به سال:
Small area ecological studies are commonly used in epidemiology to assess the impact of area level risk factors on health outcomes when data are only available in an aggregated form. However, the resulting estimates are often biased due to unmeasured confounders, which typically are not available from the standard administrative registries used for these studies. Extra information on confounder...
Many continental sister species are allopatric or parapatric, ecologically similar and long separated, of the order of millions of years. Sympatric, ecologically differentiated, species, are often even older. This raises the question of whether build-up of sympatric diversity generally follows a slow process of divergence in allopatry, initially without much ecological change. I review patterns...
AN INDIVIDUAL CORRELATION is a correlation in which the statistical object or thing described is indivisible. The correlation between color and illiteracy for persons in the United States, shown later in Table I, is an individual correlation, because the kind of thing described is an indivisible unit, a person. In an individual correlation the variables are descriptive properties of individuals...
Considerable variation exists not only in the kinds of transposable elements (TEs) occurring within the genomes of different species, but also in their abundance and distribution. Noting a similarity to the assortment of organisms among ecosystems, some researchers have called for an ecological approach to the study of transposon dynamics. However, there are several ways to adopt such an approa...
Dispersal dynamics have significant consequences for ecological and evolutionary processes. Previous work has demonstrated that dispersal can be context-dependent. However, factors affecting dispersal are typically considered in isolation, despite the probability that individuals make dispersal decisions in response to multiple, possibly interacting factors. We examined whether two ecological f...
Like the formation of animal species, plant speciation is characterized by the evolution of barriers to genetic exchange between previously interbreeding populations. Prezygotic barriers, which impede mating or fertilization between species, typically contribute more to total reproductive isolation in plants than do postzygotic barriers, in which hybrid offspring are selected against. Adaptive ...
Genetic diversity is one of the key evolutionary variables that correlate with population size, being of critical importance for population viability and the persistence of species. Genetic diversity can also have important ecological consequences within populations, and in turn, ecological factors may drive patterns of genetic diversity. However, the relationship between the genetic diversity ...
In this paper, we prompt public policy performance evaluation method based on local fractional algorithm. This paper takes the public value as a basic framework to build a system and it combines the execution process of ecological construction policies with the performance evaluation of the ecological effects. Then it extracts index factors from some aspects such as the "fairness" of the policy...
Key conceptual issues about speciation go unanswered without consideration of non-mutually exclusive factors. With tests based on speciation theory, we exploit the island distribution and habitat differences exhibited by the Caribbean cricket Amphiacusta sanctaecrucis, and with an analysis of divergent ecological selection, sexually selected differentiation and geographical isolation, address h...
miankaleh biosphere reserve it has a set of marine and land ecosystems an area about 67349 ha and is located in the north of iran and southeast farthermost of caspian sea. the diversity of the natural characteristics of caspian region is the cause of diversity in the habitats, and has resulted in nesting of most plant species in the germinative range. regarding the importance of coastal ecosyst...
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