Data from: The red queen coupled with directional selection favors the evolution of sex

Why sexual reproduction has evolved to be such a widespread mode of reproduction remains a major question in evolutionary biology. While previous studies have shown that increased sex and recombination can evolve in the presence of host-parasite interactions (the “Red Queen hypothesis” for sex), many of these studies have assumed that multiple loci mediate infection versus resistance. Data suggest, however, that a major locus is typically involved in antigen presentation and recognition. Here, we explore a model where only one locus mediates host-parasite interactions, but a second locus is subject to directional selection. Even though the effects of these genes on fitness are independent, we show that increased rates of sex and recombination are favored at a modifier gene that alters the rate of genetic mixing. This result occurs because of selective interference that occurs in finite populations (the “Hill-Robertson effect”), which also favors sex. These results suggest that the Red Queen hypothesis may help to explain the evolution of sex by contributing a form of persistent selection, which interferes with directional selection at other loci and thereby favors sex and recombination.为何有性生殖演化成为如此广泛的生殖模式，仍是演化生物学中的核心未解问题。此前研究表明，在宿主-寄生虫互作（即有性生殖的“红皇后假说（Red Queen hypothesis）”）存在的条件下，有性生殖与重组率的提升可以发生演化，但这类研究大多假定感染与抗性由多个基因座介导。不过现有数据显示，抗原呈递与识别过程通常由单个主要基因座主导。本文探讨了仅存在单个介导宿主-寄生虫互作的基因座，但存在第二个受定向选择作用的基因座的模型。尽管这些基因对适合度的效应相互独立，我们的研究表明，在改变遗传混合速率的修饰基因座上，更高的有性生殖与重组率会受到自然选择的青睐。这一结果源于有限种群中发生的选择性干扰（即“希尔-罗伯逊效应（Hill-Robertson effect）”），该效应同样会促进有性生殖的演化。上述结果表明，红皇后假说或许可以通过提供一种持续性选择形式，来解释有性生殖的演化：这种持续性选择会干扰其他基因座上的定向选择，从而对有性生殖和重组起到促进作用。