Dissertation Research: Sex Allocation and Reproductive Success in a Perennial Hermaphrodite, Solanum carolinense

生态学理论预测，植物上花的大小或数量对该植物的繁殖成功率有很大的影响，特别是在花粉传播方面，因此，花多或花大的植物作为父本将提高其繁殖成功率。另一方面，植物的资源池有限，不仅要用于吸引传粉者，还要分配给果实填充（雌性繁殖成功的一个组成部分）、生长、储存和生存。这导致了植物内部的基本冲突。这两种观点的综合——通过两性和分配水平的冲突获得的生殖成功——在雌雄同体植物中受到了与确定性别特定适应度和分配特定特征（如花冠（花瓣）大小）有关的问题的阻碍。本研究将结合分配和适合度成分的方法来确定不同花性状在繁殖成功中的确切作用。本研究将确定多年生植物茄茄性别功能的资源分配，并通过雄性和雌性功能将资源分配模式与实现适合度联系起来。已经种植了carolinense的实验种群，在两个生长季节（雌性适合度）和雄性父权（通过遗传分析确定）中，单个果实和种子的设置将与个体大小和花朵数量的变化有关。因此，本研究将深入了解雌雄同体植物中资源分配对两性获得的适合度的影响，以及两性之间资源分配和适合度的相互关系。此外，将在植物间进行控制杂交，以确定花性状的遗传力，从而确定分配制度的进化潜力。如果花的大小是由环境决定的（例如，如果在营养浓度稍高的地区生长的个体上发现较大的花部分），那么由于分配制度而导致的繁殖能力的任何差异都不会传递给后代，花的大小及其与繁殖成功的关系是一种随机效应。除了有助于对植物繁殖成功的基本认识外，该项目还具有潜在的应用意义。这个项目的研究物种，Solanum carolinense，在1980年被评为十大最差的牧草杂草之一，因为存在有毒的生物碱，刺和厚实的持久根，有助于单株的无性繁殖。因此，它是一个具有重要商业价值的物种。了解这种杂草的分配权衡可能有助于农民目前采取的控制措施。此外，所解决的有关权衡的具体问题可直接应用于食用植物育种工作，因为研究结果将有助于解释果实产量的品种变异是花分配变异的函数。

9411513 Meagher Ecological theories have predicted that the size or number of flowers on a plant should have a large effect upon the resulting reproductive success of that plant, particularly in terms of pollen spread, so that a plant with more or larger flowers will increase its reproductive success as a male parent. On the other hand, a plant has a limited resource pool which must be allocated not only to attracting pollinators, but also to filling fruit (a component of female reproductive success), growth, storage, and survival. This leads to a basic conflict within a plant. Synthesis of these two ideas--reproductive success gained through each gender and allocation-level-conflicts--has been hampered in hermaphroditic plants by problems associated with determining gender-specific fitness and assigning specific characters, such as corolla (petal) size, to either male or female success. This study will integrate allocation and fitness-component approaches to identify the precise role of different floral characters in reproductive success. The proposed research will determine resource allocation to gender functions in the perennial plant Solanum carolinense, and relate allocation patterns to realized fitness through both male and female functions. Experimental populations of S. carolinense have been planted, within which individual fruit and seed set over two growing seasons (female fitness) and male paternity (determined through genetic analysis) will be related to individual variation in the size and number of flowers. This study will therefore provide insight into the effect of resource allocation on the fitness gained through each gender in a hermaphroditic plant, and into the interrelationships of allocation and fitness between genders. In addition, controlled crosses will be performed between plants to determine the heritability of floral characters, so as to ascertain the potential for evolution of allocation regime. If flower size is environ mentally determined (for example, if larger flower parts are found on individuals growing in areas of slightly higher nutrient concentrations), any difference in reproductive ability due to allocation regime will not be passed on to offspring, and flower size and its relation to reproductive success is a random effect. In addition to contributions to basic understanding of plant reproductive success, this project will also have potential applied significance. The study species for this project, Solanum carolinense, was named one of the ten worst pasture weeds in 1980, due to the presence of toxic alkaloids, prickles, and thick persistent roots which aid in clonal spread of individual plants. It is therefore a commercially important species. Understanding allocation tradeoffs in this weed could contribute to control efforts currently practiced by farmers. In addition, the specific questions addressed concerning tradeoffs have direct applications to food plant breeding efforts, in that the results will help to explain cultivar variation in fruit production as a function of variation in floral allocation.