Neutral behavior of shared polymorphism
Neutral behavior of shared polymorphism
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DOI：
10.1073/pnas.94.15.7730
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发表时间：
1997-07-22
影响因子：
11.1
通讯作者：
Clark, AG
中科院分区：
文献类型：
--
作者：
Clark, AG
在文献中描述了几种情况，其中遗传多态性似乎在一对物种之间共享。在这里，我们在中性赖特-费舍尔模型的背景下研究了共享多态性随机丢失的时间分布。顺序统计量被用来获得的时间分布的损失的共享多态性的基础上木村的解决方案的扩散近似的赖特-费舍尔模型。在一个单一的物种中，具有初始等位基因频率为1/2的中性等位基因的预期吸收时间是2.77 N代。如果两个物种最初共享多态性，那么一旦两个物种中的任何一个经历固定，共享的多态性就会消失。因此，一个共享的多态性的损失发生早于损失的多态性在一个单一的物种，并有一个预期的时间为1.7 N代。具有共享多态性的基因的分子序列可以通过在两个物种中分离相同核苷酸（或氨基酸）的位点的数目的计数来表征。这些共享多态位点的预期数量的分布也得到了。共享多态性似乎更可能在遗传位点，有一个异常大量的分离等位基因，和中性聚结证明是非常有用的，在确定共享等位基因谱系的概率预期的机会。这些结果与文献中共享多态性的例子有关。
Several cases have been described in the literature where genetic polymorphism appears to be shared between a pair of species. Here we examine the distribution of times to random loss of shared polymorphism in the context of the neutral Wright-Fisher model. Order statistics were used to obtain the distribution of times to loss of a shared polymorphism based on Kimura's solution to the diffusion approximation of the Wright-Fisher model. In a single species, the expected absorption time for a neutral allele having an initial allele frequency of 1/2 is 2.77 N generations. If two species initially share a polymorphism, that shared polymorphism is lost as soon as either of two species undergoes fixation. The loss of a shared polymorphism thus occurs sooner than loss of polymorphism in a single species and has an expected time of 1.7 N generations. Molecular sequences of genes with shared polymorphism may be characterized by the count of the number of sites that segregate in both species for the same nucleotides (or amino acids). The distribution of the expected numbers of these shared polymorphic sites also is obtained. Shared polymorphism appears to be more likely at genetic loci that have an unusually large number of segregating alleles, and the neutral coalescent proves to be very useful in determining the probability of shared allelic lineages expected by chance. These results are related to examples of shared polymorphism in the literature.