Hoekstra R F
Experientia Suppl. 1987;55:59-91. doi: 10.1007/978-3-0348-6273-8_3.
It is very likely that sexual differentiation into two morphologically indistinguishable mating types has preceded the evolution of anisogamy. Therefore, the study of the evolution of mating types in an isogamous population is more informative for understanding the forces responsible for the evolution of different sexes than the study of the evolution of anisogamy; the latter represents the secondary problem of how, after the establishment of two sexes, an increasing degree of gamete dimorphism may evolve. Mating type evolution has been analyzed theoretically in population genetic models. These explorations show that mating types may evolve as a consequence of selection for more efficient gamete recognition, and also as a result of intragenomic conflict between nuclear and cytoplasmic DNA. However, in both cases the selection forces have to be very strong, which makes these possible explanations less convincing. Nearly all theories proposed for the evolution of anisogamy assume two conflicting selection forces to be relevant: selection for greater gamete productivity, and selection for greater zygote size. Although the explanation is intuitively plausible, the comparative evidence is a bit disappointing. Alternatively, anisogamy can be explained as a side-effect of selection for a greater efficiency in finding a mating partner by using sexual pheromones. Firm empirical evidence is lacking, however. In both problem areas--mating type evolution and anisogamy evolution--experimental work is badly needed.
在异形配子进化之前，很可能已经发生了向两种形态上无法区分的交配型的性别分化。因此，研究同配生殖群体中交配型的进化，对于理解导致不同性别的进化力量，比研究异形配子的进化更具启发性；后者代表的是一个次要问题，即两性确立后，配子二态性程度的增加是如何进化的。在群体遗传模型中，已经从理论上分析了交配型的进化。这些探索表明，交配型可能是由于对更高效配子识别的选择而进化的，也可能是核DNA与细胞质DNA之间基因组内冲突的结果。然而，在这两种情况下，选择力都必须非常强大，这使得这些可能的解释不那么令人信服。几乎所有关于异形配子进化提出的理论都假定两种相互冲突的选择力是相关的：对更高配子生产力的选择，以及对更大合子大小的选择。虽然这种解释直观上似乎合理，但比较证据却有点令人失望。或者，异形配子可以解释为通过使用性信息素在寻找交配伙伴时提高效率的选择的副作用。然而，缺乏确凿有力的经验证据。在这两个问题领域——交配型进化和异形配子进化——都非常需要实验工作。
