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

9319002 DELPH这项研究针对高山冻土带植物Silene acaulis的后代存活能力差异可能的遗传机制进行了研究。无茎海鞘的交配系统被称为“雌雄异株”，其中有两种类型的个体：雌性个体和两性个体。这与大多数开花植物物种不同，在开花植物物种中，只出现两性的。据报道，雌性变种的后代在成苗阶段存活的可能性是种子父母是两性的后代的9倍。尽管雌性的种子比两性的种子更小，含有的营养物质也更少，但这仍然是事实。这表明这与遗传机制有关。三种解释雌性种子质量较高的遗传假说将通过田间和实验室实验进行验证。这项由这笔赠款资助的工作将深入了解(1)如何选择影响有机体中一种以上性状的基因，(2)相关个体之间的交配如何影响后代的适应性，以及(3)不同遗传构成的花粉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，因为将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保持的能力不同，这项工作促进了对造成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.