TAILIEUCHUNG - Báo cáo sinh học: "Genome size variation and evolution in North American cyprinid fishes"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học Journal of Biology đề tài: Genome size variation and evolution in North American cyprinid fishes | Genet Sei Evol 1990 22 11-29 Elsevier INRA 11 Original article Genome size variation and evolution in North American cyprinid fishes JR Gold CJ Ragland LJ Schliesing Department of Wildlife and Fisheries Sciences Texas A M University College Station TX 77843 USA Received 4 January 1989 accepted 11 October 1989 Summary - Genome sizes nuclear DNA contents were documented spectrophotomet-rically for 29 species of North American cyprinid fishes. The data were then merged with comparable genome size data published previously from an additional 20 North American cyprinid species. The distributions of DNA values within populations of the 49 cyprinid species were essentially continuous and normal. The proportion of DNA which apparently is free to vary quantitatively within cyprinid populations appears to be between 4 and 5 of the genome. The distribution of DNA values among cyprinid species was more-or-less continuous with considerable overlap among species with intermediate DNA values. Analysis of the average genome size difference distance between individuals drawn from successive levels of evolutionary divergence indicated that i the majority of genome size divergence in North American cyprinids has occurred above the level of individuals within populations of species and ii the degree of genome size divergence in the extremely speciose cyprinid genus Notropis is greater than that between species in other less speciose cyprinid genera The hypothesis that genome size change might be concentrated in speciation episodes was tested by comparing the means and variances of genome size difference distance between species in the cyprinid genus Notropis a species-rich phylad and the centrarchid sunfish genus Lepomis a species-poor phylad . The ratios of mean distances and variances in the Notropis versus Lepomis comparisons were greater than unity suggesting that changes in genome size in cyprinids may be correlated with speciation episodes. Whether or not genome size change in .

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