Genome expansion in early eukaryotes drove the transition from lateral gene transfer to meiotic sex.
Genome expansion in early eukaryotes drove the transition from lateral gene transfer to meiotic sex.
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DOI：
10.7554/elife.58873
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发表时间：
2020-09-29
期刊：
影响因子：
7.7
通讯作者：
Pomiankowski A
中科院分区：
文献类型：
--
作者：
Colnaghi M;Lane N;Pomiankowski A
原核生物通过横向基因转移（LGT）从环境中获得基因。环境DNA的降解可以防止有害突变的积累，但第一批真核生物放弃了LGT，转而支持有性生殖。在这里，我们开发了一个理论模型的一个单倍体群体进行LGT，其中包括两个新的参数，基因组大小和重组长度，被忽略了以前的理论模型。真核生物的更大的复杂性与更大的基因组有关，我们证明了LGT的益处随着基因组大小迅速下降。较大基因组的退化只能通过增加重组长度来抵抗，重组长度的数量级与基因组大小相同--就像减数分裂中发生的那样。我们的结果可以解释早期真核进化过程中性细胞融合和相互重组进化的强烈选择压力--减数分裂性别的起源。
Prokaryotes acquire genes from the environment via lateral gene transfer (LGT). Recombination of environmental DNA can prevent the accumulation of deleterious mutations, but LGT was abandoned by the first eukaryotes in favour of sexual reproduction. Here we develop a theoretical model of a haploid population undergoing LGT which includes two new parameters, genome size and recombination length, neglected by previous theoretical models. The greater complexity of eukaryotes is linked with larger genomes and we demonstrate that the benefit of LGT declines rapidly with genome size. The degeneration of larger genomes can only be resisted by increases in recombination length, to the same order as genome size – as occurs in meiosis. Our results can explain the strong selective pressure towards the evolution of sexual cell fusion and reciprocal recombination during early eukaryotic evolution – the origin of meiotic sex.