Dissertation Research: Testing Hypotheses for Proximate Mechanisms Generating Spatial Segregation of the Sexes

在一些植物物种中，雄性和雌性生活在不同的栖息地。该项目的目的是确定在盐草中产生这种雄性和雌性空间隔离模式的生态机制。盐草是美国西海岸和东海岸以及内陆咸碱性地区盐沼的中心组成部分。为了确定在这个物种中产生雄性和雌性空间隔离模式的机制，研究人员已经确定了能够区分克隆和在开花前识别个体性别的分子标记。有了这些工具，他们可以通过跟踪田间种子长成的幼苗，来测试不同发芽要求和不同幼苗死亡率的影响。进一步利用分子标记对已知年龄斑块的植物进行分析，可以确定不同成虫死亡率和不同营养生长是否导致了盐草的这种模式。此外，研究人员将使用移植实验来测试环境对男性和女性营养生长的差异影响，并检查男性和女性的生殖成功率。本研究项目的长期目标是充分了解生态和进化机制如何在盐草中产生雄性和雌性的空间隔离。超过18种植物表现出雄性和雌性的空间分离。在这些物种中，雄性和雌性生活在不同的环境中，包括水的可用性、盐分水平、海拔、光照水平或营养水平。引人注目的是，与男性相比，女性总是生活在压力较小的环境中（更潮湿、更少盐）。很难理解为什么雄性和雌性的空间分离不会降低这些植物的交配效率。因此，科学家们有兴趣知道是什么机制导致雄性和雌性的空间隔离，以及这种模式是否对单个植物有益。只有一项研究直接探讨了雄性和雌性的空间隔离对植物有益的问题，而且没有发表的研究表明，在遗传决定性别的物种中，是哪种机制在起作用。了解这种模式是如何运作的尤为重要，因为许多重要的湿地植物物种都表现出这种模式。湿地生态系统具有核心的环境和生态作用，为了保护和恢复湿地，研究人员需要关于湿地生态系统的信息，特别是导致它们抵抗退化和适应变化的因素。种群的遗传成分可以极大地影响它们的稳定性，从而影响它们所属的整个生态系统的稳定性。雄性和雌性的空间隔离是许多植物种群遗传学的一个方面，对此几乎一无所知。

9701338 Stanton In some plant species, males and females live in different habitats. The goal of this project is to identify what ecological mechanisms are involved in creating such a pattern of spatial segregation of males and females in saltgrass, Distichlis spicata. Saltgrass is a central component of salt marshes on the west and east coasts of the United States as well as inland in salty and alkaline areas. To determine what mechanisms could operate to create a pattern of spatial segregation of males and females in this species, the researchers have identified molecular markers capable of differentiating clones and identifying the gender of individuals before they flower. With these tools, they can test for effects of differential germination requirements and differential seedling mortality by tracking seedlings grown from seeds in the field. Further use of molecular markers on plants in patches of known ages can determine whether differential adult mortality and differential vegetative growth contribute to the pattern in saltgrass. Also, the researchers will use transplant experiments to test for differential effects of environment on vegetative growth between males and females and to examine male and female reproductive success. The long term goal of this research project is to fully understand how ecological and evolutionary mechanisms operate to create spatial segregation of males and females in saltgrass. Spatial segregation of males and females is exhibited by more than eighteen plant species. In these species, males and females are found in environments that differ in water availability, salt levels, altitude, light levels, or nutrient levels. Strikingly, females are consistently found in less stressful environments (wetter, less salty) than males. It is difficult to understand why this spatial separation of males and females would not decrease mating efficiency for these plants. Thus, scientists are interested in knowing what mechanisms lead to spatial segregation of males and females and whether the pattern benefits individual plants. Only one study has directly addressed the question of spatial segregation of males and females as a benefit to plants, and no studies have been published that demonstrate which mechanisms are working to create this pattern in species with genetic determination of gender. It is particularly important to understand how such a pattern operates because many key wetland plant species are known to exhibit the pattern. Wetland ecosystems have a central environmental and ecological role, and in order to preserve and restore wetlands, researchers need information on wetland ecosystems particularly the factors that cause them to be resistant to degradation and resilient to change. Genetic components of populations can greatly influence their stability and consequently the stability of the whole ecosystem of which they are a part. Spatial segregation of males and females is one aspect of the genetics of many plant populations for which almost nothing is known.