Genome Changes After Gene Duplication: Haploidy vs. Diploidy
Genome Changes After Gene Duplication: Haploidy vs. Diploidy
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DOI：
10.1534/genetics.110.118646
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发表时间：
2010-09-01
期刊：
影响因子：
3.3
通讯作者：
Fu, Yun-Xin
中科院分区：
文献类型：
--
作者：
Xue, Cheng;Huang, Ren;Fu, Yun-Xin
由于基因组的大小和重复基因的数量从单倍体增加到二倍体，二倍体可能通过基因复制提供了更多的进化可能性。目前尚不清楚二倍体如何促进基因组进化的细节。在本研究中，我们通过分析和模拟的方法探讨了单倍体和二倍体群体中片段基因重复的进化。结果表明：(1)在双零隐性（DNR）选择模型下，在相同的重组率下，相同基因库大小的单倍体和二倍体群体的进化轨迹和结果非常相似；(2)重组增加了单倍体或二倍体大群体中重复基因保存的可能性，单倍体缺失强化了这一效应；(3)在重组条件下，祖先位点上重复基因的丢失是有限的，而在完全连锁条件下，祖先位点和新复制位点上重复基因的丢失总是随机的。因此，我们提出了一个模型来解释二倍体的优势：二倍体可能促进重组率的增加，特别是在有性生殖的情况下；更多的重复基因在更多的原始重组（在DNR或单倍体不足选择模型下，重复基因在一种特殊的准突变选择平衡下被完整保存）下被保存，因此二倍体生物的基因组大小和重复基因的数量变得更大。此外，由于重复基因的随机丢失而导致的小的基因组重排可能在重组中受到限制。
Since genome size and the number of duplicate genes observed in genomes increase from haploid to diploid organisms, diploidy might provide more evolutionary probabilities through gene duplication. It is still unclear how diploidy promotes genomic evolution in detail. In this study, we explored the evolution of segmental gene duplication in haploid and diploid populations by analytical and simulation approaches. Results show that (1) under the double null recessive (DNR) selective model, given the same recombination rate, the evolutionary trajectories and consequences are very similar between the same-size gene-pool haploid vs. diploid populations; (2) recombination enlarges the probability of preservation of duplicate genes in either haploid or diploid large populations, and haplo-insufficiency reinforces this effect; and (3) the loss of duplicate genes at the ancestor locus is limited under recombination while under complete linkage the loss of duplicate genes is always random at the ancestor and newly duplicated loci. Therefore, we propose a model to explain the advantage of diploidy: diploidy might facilitate the increase of recombination rate, especially under sexual reproduction; more duplicate genes are preserved under more recombination by originalization (by which duplicate genes are preserved intact at a special quasi-mutation-selection balance under the DNR or haplo-insufficient selective model), so genome sizes and the number of duplicate genes in diploid organisms become larger. Additionally, it is suggested that small genomic rearrangements due to the random loss of duplicate genes might be limited under recombination.