Department of Biology, Concordia University, 7141 Sherbrooke West, Montreal, QC H4B 1R6, Canada.
Department of Biology, McMaster University, 1280 Main St. West, Hamilton, ON L8S 4K1, Canada.
Genome. 2019 Nov;62(11):761-768. doi: 10.1139/gen-2019-0051. Epub 2019 Sep 3.
The cumulative reproductive cost of multi-locus selection has been considered to be a potentially limiting factor on the rate of adaptive evolution. In this paper, we show that Haldane's arguments for the accumulation of reproductive costs over multiple loci are valid only for a clonally reproducing population of asexual genotypes. We show that a sexually reproducing population avoids this accumulation of costs. Thus, sex removes a perceived reproductive constraint on the rate of adaptive evolution. The significance of our results is twofold. First, the results demonstrate that adaptation based on multiple genes-such as selection acting on the standing genetic variation-does not entail a huge reproductive cost as suggested by Haldane, provided of course that the population is reproducing sexually. Second, this reduction in the cost of natural selection provides a simple biological explanation for the advantage of sex. Specifically, Haldane's calculations illustrate the evolutionary disadvantage of asexuality; sexual reproduction frees the population from this disadvantage.
多基因座选择的累积生殖代价被认为是限制适应进化速度的一个潜在因素。在本文中，我们表明，只有在无性基因型的无性克隆种群中，Haldane 关于多个基因座上生殖代价积累的论点才是有效的。我们表明，有性生殖种群可以避免这种成本的积累。因此，性消除了人们对适应进化速度的生殖限制的一种看法。我们研究结果的意义有两个方面。首先，这些结果表明，基于多个基因的适应——例如选择作用于遗传变异的固定等位基因——并不需要像 Haldane 所暗示的那样付出巨大的生殖代价，当然前提是种群是有性繁殖的。其次，自然选择成本的降低为性的优势提供了一个简单的生物学解释。具体来说，Haldane 的计算说明了无性繁殖的进化劣势；有性繁殖使种群摆脱了这种劣势。
