منابع مشابه
Plant speciation.
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 ...
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Ecology affects each of the three principal processes leading to speciation: genetic differentiation among populations within species, acquisition of reproductive isolation among populations, and the rise of ecological differentiation among such populations, allowing them to coexist. Until recently, however, the ties between ecology and speciation in plants have received relatively little atten...
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It has long been recognized that interspecific hybridization is common in plants, enhancing processes of diversification and speciation. With the widespread utilization of molecular tools, interspecific hybridization – as revealed through incongruence among two or more phylogenetic data sets – is now inferred to be even more prevalent than indicated by morphological and cytogenetic evidence. Us...
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As children receiving new toys, we are approaching a great new world of fantasy. Three-dimensional image devices arrived at the port of Orthodontics with increasingly strong anchors firmly holding to the ground. In this case, immobility is symbolical and inversely proportional to the ongoing possibilities we are not even capable to imagine. Perhaps, the French novelist Julio Verner could. Where...
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Abstract— The paper addresses geometric aspects of a spatial three-degree-of-freedom parallel module, which is the parallel module of a hybrid serial-parallel 5-axis machine tool. This parallel module consists of a moving platform that is connected to a fixed base by three nonidentical legs. Each leg is made up of one prismatic and two pairs of spherical joint, which are connected in a way that...
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ژورنال
عنوان ژورنال: American Anthropologist
سال: 1972
ISSN: 0002-7294,1548-1433
DOI: 10.1525/aa.1972.74.6.02a01340