Differential Seed Fitness in a Gynodioecious Plant: An Experimental Evaluation of Mechanisms

小行星9319002 这项研究探讨了高山冻原植物无茎蝇子草后代生存能力变异的遗传机制。无茎蝇子草的交配系统被称为“雌雄同体”，其中有两种类型的个体，雌性和雌雄同体。 这与大多数开花植物物种形成对比，其中只有雌雄同体。 据报道，雌性变体的后代在幼苗建立阶段存活的可能性是种子父母是雌雄同体的后代的九倍。 这是尽管事实上，从女性的种子是较小的，含有较少的营养比那些从雌雄同体。 这表明遗传机制参与其中。 三个遗传为基础的假设，以解释更高质量的种子从女性将使用现场和实验室实验进行测试。 这项资助的工作将深入了解（1）影响生物体中一种以上性状的基因是如何被选择的，（2）相关个体之间的交配如何影响后代的适应性，以及（3）遗传构成不同的花粉粒之间的竞争如何影响后代的适应性。 此外，性别决定的遗传基础将被调查，在赋予雄性不育的细胞质类型的数量将被确定。 具有不同交配系统的植物物种在自然种群中持续存在的能力不同，这项工作促进了 了解造成这种差异的机制。

9319002 Delph This research addresses the genetic mechanisms that may be responsible for variation in the ability of offspring to survive, for the alpine tundra plant, Silene acaulis. Silene acaulis has a mating system that is termed "gynodioecy", in which there are two types of individuals, females and hermaphrodites. This contrasts with the majority of flowering plant species, in which only hermaphrodites occur. It has been reported that offspring from the female morph are nine times more likely to survive the seedling establishment phase than are offspring whose seed-parents are hermaphrodites. This is in spite of the fact that the seeds from the females are smaller and contain fewer nutrients than those from hermaphrodites. This suggests that genetic mechanisms are involved. Three genetically based hypotheses to explain the higher quality of seeds from females will be tested using field and laboratory experiments. The work funded by this grant will provide insight into (1) how genes that affect more than one trait in an organism are selected for, (2) how matings between related individuals affect offspring fitness,and (3) how competition among pollen grains that differ in their genetic constitution can affect offspring fitness. Furthermore, the genetic basis of sex determination will be investigated, in that the number of cytoplasmic types conferring male-sterility will be determined. Plant species with different mating systems vary in their ability to persist in natural populations, and this work promote understanding of the mechanisms responsible for this difference.