نتایج جستجو برای: population size
تعداد نتایج: 1199768 فیلتر نتایج به سال:
Identifying factors regulating variation in numbers of individuals among populations across a species' distribution is a fundamental goal in ecology. A common prediction, often referred to as the abundant-centre hypothesis, suggests that abundance is highest near the centre of a species' range. However, because of the primary focus on the geographical position of a population, this framework pr...
Body size is a key parameter influencing demographic characteristics of fish populations as well as market value of landed catch. Yet in bioeconomic modelling body size is often an overlooked biological and economic parameter. Here we evaluate how sizedependent pricing influences optimal harvest strategies in a model parameterized for two pelagic fisheries, those targeting Atlantic herring (Clu...
The distance of pollen movement is an important determinant of the neighborhood area of plant populations. In earlier studies, we designed a method for estimating the distance of pollen dispersal, on the basis of the analysis of the differentiation among the pollen clouds of a sample of females, spaced across the landscape. The method was based solely on an estimate of the global level of diffe...
a large number of single research studies on the effects of strategy-based instruction (sbi) in teaching english as a foreign or second language has been conducted so far. however, the lack of a comprehensive meta-analysis targeting the effectiveness of english language sbi is observed. moreover, the findings of experimental studies regarding the context of the english language, proficiency lev...
Stock dynamics and demographic parameters of a family of annual icefishes (Salangidae) were investigated in Lake Nanyi in eastern China before and after construction of irrigation infrastructure. After hydroregulation, two of four icefish species, a migratory species (Hemisalanx brachyrostralis) and a previously rare species (Neosalanx tangkahkeii) were absent from survey samples. The relative ...
مطالعه حاضر با هدف شناسایی فونستیک پرندگان و مقایسه تنوع گونه ای جامعه پرندگان بین زیستگاه های مختلف شهرستان نقده انجام گرفت. برای این منظور پرندگان منطقه مورد مطالعه از تیرماه 1389 تا خرداد 1391 در چهار زیستگاه استپ های نیمه خشک، تالابی، کشاورزی و کوه های مرتفع پایش گردید. برای بررسی اهمیت هریک از زیستگاه ها برای پرندگان، شاخص های تنوع گونه ای زیستگاه ها مورد مقایسه قرار گرفت. در مجمو...
Pedigree information which collected from 1979 to 2012 were used to study the genetic variability and population structure of Raeini Cashmere goat, taking kids born from 2009 to 2012 into account as reference population. Averages of inbreeding coefficients in whole and inbred populations were computed to be 0.04% and 4.41%, respectively. Considering the reference population, average inbreeding ...
What is it? An aid to calculation in population genetics, introduced by Sewall Wright. The rate of change of the genetic make-up of a population by genetic drift — fluctuations in allele frequencies caused by random sampling — is inversely related to the effective population size, Ne. Ne is measured with reference to an ideal ‘Wright–Fisher’ population. This has a fixed number of N diploid bree...
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