DISSERTATION RESEARCH: Ecology and Evolution of Distribution Patterns in Lasthenia fremontii

遗传过程在决定植物物种在何处生长或不生长方面的作用在很大程度上仍未得到探索，尽管这一问题对于生态恢复和保护遗传生物多样性的努力具有重要意义。 这项研究将确定生态和遗传因素，可以限制分布的一年生植物限制加州的濒危春池栖息地的弗氏乳杆菌。 本研究的具体目标如下：（1）确定确定当前种群边界的生态因子; Fremontii通过移植实验。(2)考察自然选择、遗传变异和基因流动对L.适合度的相互影响。fremontii在不同深度的池通过比较成功的移植与控制遗传背景在不同海拔跨越春季池梯度。 (3)利用中性DNA变异描述春池种群内和种群间的基因流和遗传分化模式。 该项目致力于将遗传和进化过程纳入我们对影响物种分布的机制的经验理解中。 虽然自然选择，基因流和遗传变异对物种分布范围限制的影响已经在理论上进行了探索，但这些过程的实证研究几乎完全缺乏。 这项研究的更广泛的影响将扩展到保护狭义的地方性物种，特别是那些仅限于春季池栖息地，这是共同受到栖息地破坏和生物入侵的威胁。

The role of genetic processes in determining where plant species do or do not grow remains largely unexplored, despite the importance of this issue for ecological restoration and for efforts to conserve genetic biodiversity. This study will identify both ecological and genetic factors that can limit the distribution of Lasthenia fremontii, an annual plant restricted to California's endangered vernal pool habitats. The specific objectives of this research are as follows: (1) To identify ecological factors that set current population boundaries for L. fremontii through a transplant experiment. (2) To examine the interacting effects of natural selection, genetic variation and gene flow on the fitness of L. fremontii at different depths in the pools by comparing the success of transplants with controlled genetic backgrounds at different elevations across the vernal pool gradient. (3) To describe patterns of gene flow and genetic differentiation within and among vernal pool populations using neutral DNA variation. This project strives to incorporate genetic and evolutionary processes into our empirical understanding of the mechanisms that influence the distributions of species. While the effects of natural selection, gene flow, and genetic variation on species range limits have been explored theoretically, empirical studies of these processes are almost entirely lacking. Broader impacts of this study will extend to the conservation of narrowly endemic species, especially those restricted to vernal pool habitats, which are jointly threatened by habitat destruction and biological invasion.