CoMPLEX, University College London, London, United Kingdom.
Department of Genetics, Evolution and Environment University College London, London, United Kingdom.
Elife. 2020 Sep 29;9:e58873. doi: 10.7554/eLife.58873.
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.
原核生物通过水平基因转移 (LGT) 从环境中获取基因。环境 DNA 的重组可以防止有害突变的积累，但 LGT 被最初的真核生物所抛弃，转而支持有性生殖。在这里，我们开发了一个进行 LGT 的单倍体种群的理论模型，其中包括以前的理论模型忽略的两个新参数，基因组大小和重组长度。真核生物的复杂性与更大的基因组有关，我们证明 LGT 的好处随着基因组大小的增加而迅速下降。只有通过增加重组长度，使其与基因组大小相同的数量级——就像减数分裂中一样，才能抵抗更大基因组的退化。我们的研究结果可以解释为什么在早期真核生物进化过程中，朝着性细胞融合和相互重组的方向进化的选择压力如此之大——即减数分裂性的起源。
