Howard R S, Lively C M
Department of Biology, Indiana University, Bloomington 47405.
Nature. 1994 Feb 10;367(6463):554-7. doi: 10.1038/367554a0.
Two classes of models attempt to explain why obligate partheno-genesis only rarely replaces sexual reproduction in natural populations, in spite of the apparent reproductive advantage that parthenogens gain by producing only female offspring. The mutation-accumulation models suggest that sex is adaptive because it purges the genome of harmful recurrent mutations. The ecological genetic models postulate that sex is adaptive in variable environments, particularly when the relevant variation is generated by coevolutionary interactions with parasites. Both of these models have considerable merit, but would seem to have limitations. The mutation-accumulation models require high rates of mutation; the coevolutionary models require that parasites have severe fitness effects on their hosts. In addition, parasites could select for clonal diversity and thereby erode any advantage that sex gains by producing variable progeny. Here we consider the interaction between mutation accumulation and host-parasite coevolution. The results suggest that even moderate effects by parasites combined with reasonable rates of mutation could render sex evolutionarily stable against repeated invasion by clones.
有两类模型试图解释为何在自然种群中，专性孤雌生殖极少取代有性生殖，尽管孤雌生殖通过只产生雌性后代而获得了明显的繁殖优势。突变积累模型认为，有性生殖具有适应性，因为它能清除基因组中有害的反复突变。生态遗传模型假定，在多变的环境中，有性生殖具有适应性，尤其是当相关变异由与寄生虫的协同进化相互作用产生时。这两类模型都有相当的优点，但似乎也存在局限性。突变积累模型需要高突变率；协同进化模型要求寄生虫对其宿主具有严重的适合度效应。此外，寄生虫可能会选择克隆多样性，从而削弱有性生殖通过产生可变后代而获得的任何优势。在这里，我们考虑突变积累与宿主 - 寄生虫协同进化之间的相互作用。结果表明，即使寄生虫的影响适中，再加上合理的突变率，也能使有性生殖在进化上稳定，以抵御克隆的反复入侵。
