The Genetic Basis of Sex Ratio Distortion in Silene Alba

虽然传统的性别比理论预测生物体将产生大致相等的性别比例，但许多物种表现出持续的性别比偏见。因此，现在存在着关于有偏见的性别比例的丰富多样的理论。减数分裂驱动、细胞质遗传和其他性别比扭曲的非孟德尔机制可能在性别比偏向的进化中发挥主要作用。减数分裂驱动系统，包括性别比扭曲者，可能是我们理解进化过程的核心，例如性染色体进化，性别决定机制的进化和多样性，以及物种之间不育障碍的起源(包括霍尔丹规则)。初步研究表明，雌雄异株植物Silene Alva的某些家族表现出严重的雌性偏见。涉及Y染色体分子标记的研究表明，种子中存在通孔，因此不是由于雄性后代死亡率较高所致。性别比偏见是通过父本遗传或在父本身上表现出来的。这种遗传模式和其他间接证据导致一个嫌疑人和X连锁减数分裂驱动系统可能是女性偏见进化的原因。这项研究将通过正反交和回交来确定银莲性比扭曲的遗传基础。随机扩增多态性DNA标记将被用来具体研究雌性偏见是如何以及何时形成的。地理上分离的种群之间和密切相关物种之间的杂交将被用来检测性别比扭曲，这通常被恢复者抑制。最后，将确定Silene Alba自然种群的结构是否与其他性别比偏向选择机制一致。这些结果将为自然人群中影响性别比的遗传机制的性质和多样性提供信息。此外，由于性染色体标记和远缘杂交代表了研究性别比遗传学的独特方法，预计该方法将促进对其他物种性别比偏差机制的研究。

While traditional sex ratio theory predicts organisms will produce roughly equal proportions of the sexes, many species exhibit persistent sex ratio biases. Consequently, there now exists a rich diversity of theory pertaining to biased sex ratios. Meiotic drive, cytoplasmic inheritance and other non-Mendelian mechanisms of sex ratio distortion may play a major role in the evolution of biased sex ratios. Meiotic drive systems, including sex ratio distorters, may be central to our understanding of evolutionary processes such as sex chromosome evolution, the evolution and diversity of sex determining mechanisms, and the origin of sterility barriers between species (including Haldane's Rule). Initial research has shown that certain families of Silene alva, a dioecious plant, exhibit severely female biased sex ratios. Studies involving molecular markers of the Y chromosome show that the vias is present in the seed and is therefore, not due to a higher mortality of male progeny. Sex ratio bias is inherited through or expressed in the male parent. This pattern of inheritance and other circumstantial evidence lead one suspect and X-linked meiotic drive system may be responsible for the evolution of the female bias. The proposed research will determine the genetic basis of sex ratio distortion in Silene alba by using reciprocal crosses and backcrosses. RAPD markers, will be used to investigate specifically how and when the female bias develops. Crosses among geographically separated populations and among closely related species will be used to detect sex ratio distortion which is normally suppressed by restorers. Finally, whether the structure of natural populations of Silene alba is consistent with other mechanisms of selection for biased sex ratios will be determined. These results will provide information the nature and diversity of genetic mechanisms influencing sex ratio in natural populations. Moreover, because sex chromosome markers and wide crosses represent unique approaches to studying sex ratio genetics,it is expected that methods will stimulate research into mechanisms of sex ratio bias in other species.