Dries Laurie A
Department of Integrative Biology, University of Texas, Austin, Texas 78712, USA.
Evolution. 2003 Jun;57(6):1387-96. doi: 10.1111/j.0014-3820.2003.tb00346.x.
The gynogenetic Amazon molly (Poecilia formosa) is a clonal, all-female lineage of livebearing fish that faces an unusual obstacle to evolutionary persistence. Sperm from heterospecific males (either sailfin, P. latipinna, or Atlantic, P. mexicana, mollies) is necessary to trigger embryogenesis. However, none of the male's genes are incorporated into the genome of the gynogenetic offspring. Some investigators have proposed that the evolution of male mate discrimination is a result of this cost, leading to a coevolutionary arms race between male avoidance of P. formosa and P. formosa attractiveness. Given that P. formosa successfully reproduces and has not yet gone extinct, it is clear there are mechanisms by which they attract the sexual attention of males. Although a Red Queen coevolutionary process in typical host/parasite systems has been shown to favor the persistence of sexual species, in this system an arms race has been invoked to explain the reverse. Here I present behavioral data supporting a more parsimonious scenario: that mechanisms of attraction in P. formosa are simply a consequence of its hybrid origin. Poecilia latipinna and P. mexicana males do not discriminate between gynogenetic P. formosa females and first generation sexual hybrid females, and females do not differ in agonistic behaviors associated with competition for mates. Both results contradict predictions from the Red Queen hypothesis. Therefore, coevolution is not necessary to explain the apparent evolutionary persistence of P. formosa.
雌核发育的亚马孙帆鳉（Poecilia formosa）是一种胎生鱼类的克隆全雌系物种，其在进化存续上面临着不同寻常的障碍。来自异种雄性（帆鳍鳉，P. latipinna，或大西洋鳉，P. mexicana）的精子对于触发胚胎发育是必需的。然而，雄性的基因不会整合到雌核发育后代的基因组中。一些研究人员提出，雄性配偶识别的进化是这种代价的结果，导致在雄性躲避亚马孙帆鳉和亚马孙帆鳉的吸引力之间展开一场协同进化的军备竞赛。鉴于亚马孙帆鳉成功繁殖且尚未灭绝，显然存在一些机制使其能够吸引雄性的性关注。虽然在典型的宿主/寄生虫系统中，红皇后协同进化过程已被证明有利于有性物种的存续，但在这个系统中，一场军备竞赛被用来解释相反的情况。在这里，我展示的行为数据支持了一个更简洁的设想：亚马孙帆鳉的吸引机制仅仅是其杂交起源的结果。帆鳍鳉和大西洋鳉的雄性不会区分雌核发育的亚马孙帆鳉雌鱼和第一代有性杂交雌鱼，并且雌鱼在与配偶竞争相关的争斗行为上也没有差异。这两个结果都与红皇后假说的预测相矛盾。因此，协同进化并非解释亚马孙帆鳉明显的进化存续所必需的。
