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

9319002 Delph本研究探讨了高山冻土带植物雪莲（Silene acaulis）后代生存能力变异的遗传机制。青花有一种被称为“雌心异体”的交配系统，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形成鲜明对比，在开花植物中只有雌雄同体。据报道，雌性形态的后代在幼苗建立阶段存活的可能性是雌雄同体的后代的9倍。尽管雌性的种子比雌雄同体的种子更小，含有的营养成分也更少。这表明这与遗传机制有关。三种基于遗传学的假设将通过田间和实验室实验来解释雌性种子的高质量。这项由该基金资助的工作将深入了解(1)影响生物体多个性状的基因如何被选择，(2)相关个体之间的交配如何影响后代的适应性，以及(3)遗传结构不同的花粉粒之间的竞争如何影响后代的适应性。此外，还将研究性别决定的遗传基础，从而确定导致雄性不育的细胞质类型的数量。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各不相同，这项工作促进了对这种差异的机制的理解。

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.