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

尽管遗传过程对生态恢复和保护遗传生物多样性的努力具有重要意义，但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。这项研究将确定生态和遗传因素可以限制Lasthenia fremontii的分布，Lasthenia fremontii是一种局限于加州濒临灭绝的春水池栖息地的一年生植物。本研究的具体目的如下：(1)通过移栽试验，找出决定fremontii种群边界的生态因子。(2)通过比较不同海拔高度春水池梯度下可控遗传背景移植的成功情况，探讨自然选择、遗传变异和基因流对不同深度池中fremontii适合度的交互作用。(3)利用中性DNA变异描述春池种群内部和种群间的基因流动和遗传分化模式。该项目努力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、基因流动和遗传变异对物种范围限制的影响已经从理论上进行了探讨，但对这些过程的实证研究几乎完全缺乏。本研究的广泛影响将扩展到狭窄的特有物种的保护，特别是仅限于春水池生境的物种，这些物种受到栖息地破坏和生物入侵的共同威胁。

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.