منابع مشابه
The Whereabouts of an Ancient Wanderer: Global Phylogeography of the Solitary Ascidian Styela plicata
Genetic tools have greatly aided in tracing the sources and colonization history of introduced species. However, recurrent introductions and repeated shuffling of populations may have blurred some of the genetic signals left by ancient introductions. Styela plicata is a solitary ascidian distributed worldwide. Although its origin remains unclear, this species is believed to have spread worldwid...
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The lesser wanderer butterfly, Danaus ( Anosia ) chrysippus petilia (Stoll) (Lepidoptera: Danainae), has been treated as a subspecies for the last 100 years. New mitochondrial DNA sequence data for D. petilia , in conjunction with allozyme, structural, morphometric and pattern characters, constitute a compelling case for its specific rank. The holotype of D. petilia has never been located and, ...
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Since 1975, an increase in the return to years of schooling, in the percentage of the labor force that is skilled, and in the variance of wage income within skill categories have characterized the U.S. labor market. While the first two facts point towards an increase in the demand for skilled labor, the third fact establishes that this increase in demand has not been uniform for all members of ...
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ژورنال
عنوان ژورنال: Nature
سال: 2002
ISSN: 0028-0836,1476-4687
DOI: 10.1038/416597a