Agrawal Aneil F
Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada.
Evolution. 2009 Aug;63(8):2131-41. doi: 10.1111/j.1558-5646.2009.00695.x. Epub 2009 Mar 27.
The Red Queen hypothesis argues that parasites generate selection for genetic mixing (sex and recombination) in their hosts. A number of recent papers have examined this hypothesis using models with haploid hosts. In these haploid models, sex and recombination are selectively equivalent. However, sex and recombination are not equivalent in diploids because selection on sex depends on the consequences of segregation as well as recombination. Here I compare how parasites select on modifiers of sexual reproduction and modifiers of recombination rate. Across a wide set of parameters, parasites tend to select against both sex and recombination, though recombination is favored more often than is sex. There is little correspondence between the conditions favoring sex and those favoring recombination, indicating that the direction of selection on sex is often determined by the effects of segregation, not recombination. Moreover, when sex was favored it is usually due to a long-term advantage whereas short-term effects are often responsible for selection favoring recombination. These results strongly indicate that Red Queen models focusing exclusively on the effects of recombination cannot be used to infer the type of selection on sex that is generated by parasites on diploid hosts.
红皇后假说认为,寄生虫会促使其宿主进行基因混合(有性生殖和重组)。最近有一些论文使用单倍体宿主模型对这一假说进行了研究。在这些单倍体模型中,有性生殖和重组在选择上是等效的。然而,在二倍体中,有性生殖和重组并不等效,因为对有性生殖的选择既取决于分离的结果,也取决于重组的结果。在此,我比较了寄生虫如何对有性生殖修饰因子和重组率修饰因子进行选择。在一系列广泛的参数范围内,寄生虫往往会对有性生殖和重组都进行负选择,不过相比于有性生殖,重组更常受到青睐。有利于有性生殖的条件和有利于重组的条件之间几乎没有对应关系,这表明对有性生殖的选择方向通常由分离效应而非重组效应决定。此外,当有性生殖受到青睐时,通常是由于长期优势,而短期效应往往是有利于重组的选择的原因。这些结果有力地表明,仅关注重组效应的红皇后模型不能用于推断寄生虫对二倍体宿主的有性生殖所产生的选择类型。