Schultz Stewart T
Biology Department, University of Oregon, Eugene, Oregon, 97403.
Evolution. 1994 Dec;48(6):1933-1945. doi: 10.1111/j.1558-5646.1994.tb02224.x.
Population-genetic models of nucleo-cytoplasmic gynodioecy are shown to allow invasion of males and conversion to dioecy in a single cytotype. Pleiotropic effects of restorer alleles on fertility through male or female function can maintain a cytoplasmic polymorphism in a population that prevents evolution to dioecy regardless of the pollen fertility of males. However, a cytoplasmic polymorphism has little effect on, and may even reduce, the minimum pollen fertility required for the spread of males into an equilibrium gynodioecious population. Where the thresholds for dioecy are similar, the presence of males during a transient preequilibrium high frequency of females can accelerate evolution to dioecy by more than 50 times relative to nuclear male sterility. However, the appearance of a nonrestorable male-sterile cytotype generally eliminates males from both subdioecious and dioecious populations, converting them to purely cytoplasmic gynodioecy. These models contradict the previously suggested notion that nucleo-cytoplasmic gynodioecy represents a "stable" intermediate breeding system and instead show that such gynodioecy can generally evolve to subdioecy, and often to dioecy, as easily as nuclear gynodioecy.
核质雌全异株的群体遗传模型表明，在单一细胞类型中，雄性能够入侵并转变为雌雄异株。恢复基因通过雄性或雌性功能对育性产生的多效性作用，可以在群体中维持细胞质多态性，从而阻止向雌雄异株的进化，无论雄性的花粉育性如何。然而，细胞质多态性对雄性扩散到平衡的雌全异株群体所需的最低花粉育性影响很小，甚至可能降低这一育性。在雌雄异株的阈值相似的情况下，在短暂的平衡前高频率雌性阶段出现雄性，相对于核雄性不育，可使向雌雄异株的进化加速50倍以上。然而，不可恢复的雄性不育细胞类型的出现通常会使亚雌雄异株和雌雄异株群体中的雄性消失，将它们转变为纯细胞质雌全异株。这些模型与之前提出的核质雌全异株代表一种“稳定”的中间繁殖系统的观点相矛盾，相反，这些模型表明，这种雌全异株通常可以像核雌全异株一样容易地进化为亚雌雄异株，并且常常进化为雌雄异株。
