Collaborative Research: Developmental Ecology of Mayapple

9410086琼斯一种植物是否能够在特定的自然环境中生存，取决于它在进化过程中的繁殖成功或适应性。繁殖成功的决定因素包括繁殖的时间表，即生活史，以及可用于繁殖的资源。由于植物的繁殖成功直接受到生殖结构(花)数量的影响，植物面临着在产生立即增加生殖产量的花朵和产生新的营养结构(叶和根)之间的权衡，这些新的营养结构提高了资源的吸收，并可能在植物整个生命周期内导致更高的繁殖成功。这种权衡由于以下两方面的相互作用而变得复杂：(1)植物固有的发育程序，它影响何时以及何种类型的新结构的形成；(2)该结构在资源积累方面的效率，这反过来又影响植物随后的发育程序。植物的发育程序和资源积累之间的这种相互作用对种群中生殖个体的比例，即种群的人口统计学的影响，人们了解得很少。我们将研究草本植物多年生克隆植物--菠萝的发育程序、资源吸收和利用以及人口统计学之间的相互作用。因为每年每个根茎都面临着一个简单的发展决定--要么长出一片叶，要么长出一朵花和两片叶的简单生殖枝，因此蛋黄果是进行这项研究的理想植物。对自然发生的种群的长期研究将被用来(1)建立一个发展决策时间表，强调如何以及何时确定新的空中“嫩枝”类型，(2)检查过去获得的资源和本年度获得的资源之间的相互作用，以确定当前和未来的嫩枝类型决定，以及(3)确定不同无性系之间发育事件的时间差异是否影响其长期繁殖产量。这项研究的结果将揭示发育时间和资源摄取的变化如何影响人口统计学。此外，这项研究将揭示哪些时间点的选择可能会改变表达的发育程序的时间，从而有助于我们理解不同的生活史是如何进化的，这是植物面临快速变化的环境的关键问题。这些结果将有助于理解发育时间的变化如何影响经济上重要的植物的营养和生殖生产力。

9410086 Jones Whether a plant is able to persist in a particular natural environment is determined by its reproductive success, or fitness, through evolutionary time. Among the determinants of reproductive success are the schedule of reproduction, i.e. the life history, and the resources available for reproduction. Because a plant's reproductive success is directly influenced by the number of reproductive structures (flowers), plants face a tradeoff between producing flowers that increase reproductive output immediately, versus producing new vegetative structures (leaves and roots) that enhance resource uptake and may lead to higher reproductive success over the life of the plant. This tradeoff is complicated by the interaction between (1) a plant's inherent developmental program, which influences when and what type of new structure will be made, and (2) the efficiency of that structure in resource accumulation, which in turn influences the plant's subsequent developmental program. The influence of this interaction between a plant's developmental program and resource accumulation on the proportion of reproductive individuals in the population, i.e. the population's demography, is poorly understood. Interactions between developmental program, resource uptake and use, and demography in an herbaceous perennial clonal plant, mayapple (Podophyllum peltatum) will be examined. Mayapple is an ideal plant for such a study because each year each rhizome faces a simple developmental decision--to produce either a single foliage leaf, or a simple reproductive shoot bearing a single flower and two foliage leaves. Long-term studies of naturally occurring populations will be used to (1) construct a timetable of developmental decisions for mayapple, emphasizing how and when the type of new aerial "shoot" is determined, (2) examine the interaction between resources acquired in the past and those acquired in the current year on current and future determination of shoot type and (3) determine whether dif ferences in the timing of developmental events among different clones affects their reproductive output over the long term. The results of this study will reveal how variation in developmental timing and resource uptake affect demography. Moreover, this study will reveal at what points selection may act to alter the timing of the expressed developmental program, thus contributing to our understanding of how different life histories evolve, a critical issue for plants facing a rapidly changing environment. These results will contribute to understanding how variation in developmental timing affects vegetative and reproductive productivity in economically important plants as well.