COLLAB. RES.:Relative Fitness and Gender in Wild Populationsof Spergulaic marina (the sand-spurrey: Caryophyllaceae): AnExamination of the Assumptions of Theoretical Models

沙刺草（Spergularia marina）是世界各地常见的天然滨海湿地生境。像大多数植物一样，花通过产生花粉粒和胚珠产生雄性和雌性配子。然而，与大多数物种相比，花楸在花粉产量上表现出10倍的差异，这代表了雄性生殖的分配。此外，在开花植物中，这种变异范围并不罕见，但在平均胚珠产量上（每花50到150个胚珠）却有三倍的差异。更重要的是，雄蕊数和胚珠数的变异都具有遗传基础，因此很可能随着时间的推移而表现出对选择的反应。因此，这个物种提供了一个很好的机会来研究花资源分配给雄性和雌性配子的变化的原因和后果，通常被称为“性别分配”。目前，虽然关于这一主题的理论工作很多，但还没有对这一理论的假设进行深入探讨的实证研究。例如，长期以来人们一直认为，增加雄性分配（如高花粉产量）的选择必然导致雌性分配（如减少胚珠或契据产量）的减少，从而促进专门生殖系统的进化。然而，这一假设从未得到充分的检验。我们对沙棘生态遗传学的研究将通过测量雄蕊和胚珠产生的遗传成分，以及测量与雄性或雌性繁殖增加分配相关的任何“成本”，来检验性别分配理论的假设。此外，我们的数据将允许评估S. marina及其相似物种的进化灵活性，以及其改变其生产生物学以应对日益受到威胁的栖息地变化的能力。

Sand-spurrey, Spergularia marina, is a common species of natural coastal wetland habitats throughout the world. Like most plant species, flowers of S. marina produce both male and female gametes through the production of pollen grains and ovules. However, in contrast to most species, S. marina exhibits ten-fold variation in pollen production, which represents allocation to male reproduction. In addition, S. marina individuals show three-fold variation in average ovule production (from 50 to 150 ovules per flower), although this range of variation is not uncommon in flowering plants. More importantly, the variation in both stamen number and ovule number has a genetic basic and is thus likely to show change over time in response to selection. This species, therefore, provides an excellent opportunity to investigate the causes and consequences of variation in the allocation of floral resources to male and female gametes, commonly known as "gender allocation". Currently, although there exists a great deal of theoretical work on this topic, there are no empirical studies that explore thoroughly the assumptions of this theory. For example, it has long been believed that selection to increase male allocation (e.g. high pollen production) should necessarily result in a reduction in female allocation (e.g., reduced ovule or deed production), promoting the evolution of specialized reproductive systems. This assumption, however, has never been adequately tested. Our study of the ecological genetics of sand-spurrey will test the assumptions of gender allocation theory by providing measurements of the genetic component to stamen and ovule production and measurements of any "costs" associated with increased allocation to male or female reproduction. Moreover, our data will allow an evaluation of the evolutionary flexibility of S. marina - and species similar to it - and its ability to alter its productive biology in response to changes in its increasingly threatened habitat.