UMR 6553 Ecologie Biodiversité Evolution, CNRS INEE, Université de Rennes 1, OSUR, Campus de Beaulieu, Rennes Cedex, France.
IGEPP, INRAE, Institut Agro, Université de Rennes, Le Rheu, France.
PLoS One. 2022 Aug 2;17(8):e0272134. doi: 10.1371/journal.pone.0272134. eCollection 2022.
The advantage of sex, and its fixation in some clades and species all over the eukaryote tree of life, is considered an evolutionary enigma, especially regarding its assumed two-fold cost. Several likely hypotheses have been proposed such as (1) a better response to the negative frequency-dependent selection imposed by the "Red Queen" hypothesis; (2) the competition between siblings induced by the Tangled Bank hypothesis; (3) the existence of genetic and of (4) ecological factors that can diminish the cost of sex to less than the standard assumed two-fold; and (5) a better maintenance of genetic diversity and its resulting phenotypic variation, providing a selective advantage in randomly fluctuating environments. While these hypotheses have mostly been studied separately, they can also act simultaneously. This was advocated by several studies which presented a pluralist point of view. Only three among the five causes cited above were considered yet in such a framework: the Red Queen hypothesis, the Tangled Bank and the genetic factors lowering the cost of sex. We thus simulated the evolution of a finite mutating population undergoing negative frequency-dependent selection on phenotypes and a two-fold (or less) cost of sexuality, experiencing randomly fluctuating selection along generations. The individuals inherited their reproductive modes, either clonal or sexual. We found that exclusive sexuality begins to fix in populations exposed to environmental variation that exceeds the width of one ecological niche (twice the standard deviation of a Gaussian response to environment). This threshold was lowered by increasing negative frequency-dependent selection and when reducing the two-fold cost of sex. It contributes advocating that the different processes involved in a short-term advantage of sex and recombination can act in combination to favor the fixation of sexual reproduction in populations.
性的优势及其在真核生物树的某些进化枝和物种中的固定被认为是一个进化之谜，尤其是考虑到其假定的双重代价。已经提出了几种可能的假说，例如：(1) 更好地响应“红皇后”假说所施加的负频率依赖性选择；(2)“纠缠银行”假说引起的兄弟姐妹之间的竞争；(3) 存在遗传和(4) 生态因素，可以将性的成本降低到低于标准的两倍以下；以及(5) 更好地维持遗传多样性及其由此产生的表型变异，从而在随机波动的环境中提供选择优势。虽然这些假说大多是分开研究的，但它们也可以同时起作用。这是由几个提出多元观点的研究倡导的。在这种框架中，仅考虑了上述五个原因中的三个：红皇后假说、纠缠银行和降低性成本的遗传因素。因此，我们模拟了一个有限的突变种群的进化，该种群在表型上经历负频率依赖性选择，并且性的成本为两倍（或更低），同时在世代之间经历随机波动的选择。个体继承其生殖模式，要么是克隆的，要么是有性的。我们发现，当暴露于超过一个生态位宽度的环境变化（对环境的高斯响应的标准偏差的两倍）时，无性种群开始固定。当增加负频率依赖性选择和降低性成本的两倍时，这个阈值会降低。这有助于提倡涉及性和重组的短期优势的不同过程可以结合起来，有利于性繁殖在种群中的固定。
