Jaenike John
Department of Biology, University of Rochester, Rochester, New York, 14627.
Evolution. 1999 Feb;53(1):164-174. doi: 10.1111/j.1558-5646.1999.tb05342.x.
Like several other species of Drosophila, D. quinaria is polymorphic for X-chromosome meiotic drive; matings involving males that carry a "sex-ratio" X chromosome (X ) result in the production of strongly female-biased offspring sex ratios (Jaenike 1996). A survey of isofemale lines of D. quinaria from several populations reveals that there is genetic variation for partial suppression of this meiotic drive. Crossing experiments show that there is Y-linked, and probably autosomal, variation for suppression of drive. Y-linked suppressors of X-chromosome drive have now been described in several species of Diptera. I develop a simple model for the maintenance of Y-chromosome polymorphism in species polymorphic for X-linked meiotic drive. One interesting feature of this model is that, if there is a stable Y-chromosome polymorphism, then the equilibrium frequency of the standard and sex-ratio X chromosomes is determined solely by Y-chromosome parameters, not by the fitness effects of the different X chromosomes on their carriers. This model suggests that Y-chromosome polymorphism may be easier to maintain than previously thought, and I hypothesize that karyotypic variation in Y chromosomes will be found to be associated with suppression of sex-ratio meiotic drive in other species of Drosophila.
与果蝇属的其他几个物种一样，奎纳果蝇（D. quinaria）在X染色体减数分裂驱动方面具有多态性；涉及携带“性比”X染色体（X ）的雄性果蝇的交配会产生强烈偏向雌性的后代性别比（杰尼克，1996年）。对来自几个种群的奎纳果蝇同雌系的调查显示，对于这种减数分裂驱动的部分抑制存在遗传变异。杂交实验表明，存在Y连锁以及可能的常染色体变异来抑制驱动。现在已经在几种双翅目物种中描述了X染色体驱动的Y连锁抑制因子。我建立了一个简单的模型，用于维持在X连锁减数分裂驱动方面具有多态性的物种中Y染色体的多态性。该模型的一个有趣特征是，如果存在稳定的Y染色体多态性，那么标准X染色体和性比X染色体的平衡频率仅由Y染色体参数决定，而不由不同X染色体对其携带者的适合度效应决定。这个模型表明，Y染色体多态性可能比以前认为的更容易维持，并且我推测在其他果蝇物种中会发现Y染色体的核型变异与性比减数分裂驱动的抑制有关。
