نتایج جستجو برای: clinal variation
تعداد نتایج: 296685 فیلتر نتایج به سال:
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...
Broad-scale geographical gradients in the abiotic environment and interspecific interactions should select for clinal adaptation. How trait clines evolve has recently received increased attention because of anticipated climate change and the importance of rapid evolution in invasive species. This issue is particularly relevant for clines in growth and defense of plants, because both sets of tra...
Studies of clinal variation have helped greatly in the elucidation of the mechanisms of both adaptation and speciation (Endler 1977; Barton and Hewitt 1989). Clines have been explained by selection acting within a continuous population ( primary intergradation ) or, more frequently, as the result of contact between populations differentiated in allopatry (secondary intergradation) (Endler 1977;...
We report the results of two independent selection experiments that have exposed distinct populations of Drosophila melanogaster to different forms of thermal selection. A recombinant population derived from Arvin California and Zimbabwe isofemale lines was exposed to laboratory natural selection at two temperatures (T(AZ): 18°C and 28°C). Microsatellite mapping identified quantitative trait lo...
BACKGROUND/AIMS The L1 retrotransposable element family is the most successful self-replicating genomic parasite of the human genome. L1 elements drive replication of Alu elements, and both have had far-reaching impacts on the human genome. We use L1 and Alu insertion polymorphisms to analyze human population structure. METHODS We genotyped 75 recent, polymorphic L1 insertions in 317 individu...
Parallel clines in different species, or in different geographical regions of the same species, are an important source of information on the genetic basis of local adaptation. We recently detected latitudinal clines in SNPs frequencies and gene expression of candidate genes for growth cessation in Scandinavian populations of Norway spruce (Picea abies). Here we test whether the same clines are...
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