DISSERTATION RESEARCH: Adaptation and historical ecology in vernal pool Eryngium (Apiaceae)

点击翻译按钮获取中文摘要

Vernal pools are island-like depressions characterized by seasonal extremes: flooding during winter and desiccation during summer; they are home to many endangered plants and animals. In such habitats, plants and animals must possess extreme adaptations. Many species of Eryngium occupy Californian vernal pools; these plants are closely related to carrots and parsnips. In this study, adaptations in Eryngium will be viewed from a historical perspective. DNA sequences will be collected from related species of Eryngium from California, Oregon, and Chile -- some restricted to vernal pools and some from normal terrestrial habitats. Relationships between these plants will be reconstructed from their DNA sequences. This history will give insights into how a specific adaptation, seasonal changes in leaf form, may have arisen. In Eryngium, as well as other vernal-pool plants, two types of leaves are produced: (1) winter leaves, which are well suited to flooded environments but as a trade-off produce less energy than (2) summer leaves, which are poorly suited to winter flooding. An experiment will be conducted to determine if the shift from winter leaves to summer leaves is triggered by increases in the amount of daylight per day during spring, and to determine whether leaf development is tightly constrained by genetics or if it can respond adaptively to changing environmental conditions. An important question to biologists to be addressed is whether specialization of habitat is irreversible: If plants adapt to vernal pools, are they trapped by their success? Many species of Eryngium in the vernal pools of California are in peril, and an answer to this question along with improvements in the understanding of the life history of Eryngium will aid conservation efforts. The experiment in this study gives opportunity for underrepresented minorities to learn scientific research techniques otherwise not available to undergraduates.