Intron presence-absence polymorphisms in Daphnia
Intron presence-absence polymorphisms in Daphnia
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DOI：
10.1093/molbev/msn164
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发表时间：
2008-10-01
影响因子：
10.7
通讯作者：
Lynch, Michael
中科院分区：
文献类型：
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作者：
Omilian, Angela R.;Scofield, Douglas G.;Lynch, Michael
在这里，我们报告了2个新的内含子增益分离的种群蚤状俄勒冈州特有的。这些新的内含子没有明显的来源，并且不存在于俄勒冈州以外的任何蚤状蚤种群、我们检查的其他斜体水蚤物种或任何其他可获得序列数据的生物体中。此外，新的内含子都被发现在同一个基因，一个Rab GT3（rab4），他们似乎在其插入位点不同的一个碱基对，提供了一些支持的原剪接位点假说。内含子获得多态性的罕见性受到质疑，因为我们在36个水蚤个体中仅6个核基因座的初步调查中发现了2个事件。中性测试未能确定内含子插入的明显选择性效应，我们的结论是，在俄勒冈州的斜体水蚤种群中，一个新的内含子插入以高频率分离，这不太可能是适应性的，可能是由于孤立种群中选择效率降低所致有效尺寸小。
Here, we report 2 novel intron gains segregating in populations of Daphnia pulex endemic to Oregon. These novel introns do not have an obvious source and are not present in any D.pulex populations outside Oregon, other species of italic Daphnia that we examined, or any other organism for which sequence data are available. Furthermore, the novel introns are both found in the same gene, a Rab GTPase (rab4), and they appear to differ in their insertion site by one base pair, providing some support to the proto-splice site hypothesis. The rarity of intron-gain polymorphisms is questioned as we discovered 2 events in an initial survey of only 6 nuclear loci in 36 Daphnia individuals. Neutrality tests failed to ascertain a clear selective effect for either intron insertion, and a significant difference in recombination rate was not observed in alleles that contain the novel intron insertion versus alleles lacking it. We conclude that one novel intron insertion segregating at high frequencies in italic Daphnia italic populations in Oregon is unlikely to be adaptive and may result from the reduced efficacy of selection in isolated populations of small effective size.