TAILIEUCHUNG - Báo cáo sinh học : " Is genetic diversity really higher in large populations"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học Journal of Biology đề tài: Is genetic diversity really higher in large populations? | Journal of Biology BioMed Central Minireview Is genetic diversity really higher in large populations Hans Ellegren Address Department of Evolutionary Biology Uppsala University Norbyvãgen 18D SE-752 36 Uppsala Sweden. Email Published 21 April 2009 Journal of Biology 2009 8 41 doi jbiol135 The electronic version of this article is the complete one and can be found online at http content 8M 41 2009 BioMed Central Ltd Abstract Analyses of mitochondrial DNA mtDNA have challenged the concept that genetic diversity within populations is governed by effective population size and mutation rate. A recent study in BMC Evolutionary Biology shows that variation in the rate of mutation rather than in population size is the main explanation for variations in mtDNA diversity observed among bird species. Students of population genetics learn from their textbooks that levels of genetic diversity are determined by the rate of mutation the number of new mutations per nucleotide site and generation and the number of reproducing individuals in the population. The latter is usually termed the effective population size Ne and is almost always less than the total population size. These determinants are intuitive as a higher rate of mutation creates more new genetic variants and a large population is less sensitive to random loss of variants by genetic drift. It therefore came as a surprise when it was reported a few years ago that genetic variability in mitochondrial DNA mtDNA one of the most commonly used markers in evolutionary and population genetic analysis did not seem to correlate with population size when analyzed over broad taxonomic groups. For example levels of polymorphism were found to be similar for invertebrates and vertebrates despite the fact that the former typically have much larger population sizes than the latter 1 . It was argued that the non-recombining nature of mtDNA makes its diversity prone to be shaped by natural .

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