Hanley Kathryn A, Fisher Robert N, Case Ted J
Department of Biology-0116, University of California at San Diego, La Jolla, California, 92093-0116.
Evolution. 1995 Jun;49(3):418-426. doi: 10.1111/j.1558-5646.1995.tb02274.x.
What advantage do sexually reproducing organisms gain from their mode of reproduction that compensates for their twofold loss in reproductive rate relative to their asexual counterparts? One version of the Red Queen hypothesis suggests that selective pressure from parasites is strongest on the most common genotype in a population, and thus genetically identical clonal lineages are more vulnerable to parasitism over time than genetically diverse sexual lineages. Our surveys of the ectoparasites of an asexual gecko and its two sexual ancestral species show that the sexuals have a higher prevalence, abundance, and mean intensity of mites than asexuals sharing the same habitat. Our experimental data indicate that in one sexual/asexual pair this pattern is at least partly attributable to higher attachment rates of mites to sexuals. Such a difference may occur as a result of exceptionally high susceptibility of the sexuals to mites because of their low genetic diversity (relative to other more-outbred sexual species) and their potentially high stress levels, or as a result of exceptionally low susceptibility of the asexuals to mites because of their high levels of heterozygosity.
有性生殖的生物体从其生殖方式中获得了什么优势，从而弥补了它们相对于无性生殖同类在生殖率上的两倍损失呢？红皇后假说的一个版本认为，寄生虫带来的选择压力对种群中最常见的基因型影响最大，因此随着时间的推移，基因相同的克隆谱系比基因多样的有性谱系更容易受到寄生作用的影响。我们对一种无性壁虎及其两个有性祖先物种的体外寄生虫进行的调查显示，与共享相同栖息地的无性壁虎相比，有性壁虎身上螨虫的患病率、丰度和平均强度更高。我们的实验数据表明，在一对有性/无性配对中，这种模式至少部分归因于螨虫对有性壁虎的附着率更高。这种差异可能是由于有性壁虎因其低遗传多样性（相对于其他更多远交的有性物种）和潜在的高压力水平而对螨虫异常敏感导致的，也可能是由于无性壁虎因其高杂合性水平而对螨虫异常不敏感导致的。
