RUI: Collaborative Research: The Cenozoic radiation of eupolypod ferns: did selection for drought tolerance drive the evolutionary physiology of sporophytes and gametophytes?

无种子维管束植物，如蕨类植物，是继开花植物之后多样性第二丰富的植物谱系，但由于它们的生命周期分为两个阶段，并且明显不耐干旱，它们持续成功的基础尚不完全清楚。最近的研究表明，蕨类植物的叶片（营养代）和配子体（有性代）都进化出许多策略来应对和从严重的干旱胁迫中恢复过来。本研究调查了蕨类植物生命周期中两个阶段的水分关系，以验证一种假设，即与耐旱性相关的性状的进化促进了蕨类植物从潮湿的陆地栖息地向干燥、阳光充足的冠层栖息地的扩张。研究将集中在两个最近的蕨类谱系的耐旱性状，它们代表了热带蕨类物种多样性的大部分。生理、形态和解剖属性将在野外和实验室中对选择的物种进行检查。这项基础研究不仅将扩大对形成生物多样性的过程的认识，而且还可能确定新的植物性状，有助于开发更抗旱的农业物种。学生将在墨西哥和哥斯达黎加获得国际研究经验，学生/教师交流将促进研究合作。向公众推广的活动将与拯救红木联盟和南麦迪逊遗产信托基金会的非营利性合作伙伴结合起来，说明蕨类植物和其他非维管植物在自然植物群落生态中的重要作用。为了确定干旱胁迫是否对蕨类孢子体和配子体产生强烈的趋同选择压力，本研究将对蕨类科多种植物配子体的干燥耐受性进行研究。蕨科是蕨类植物的一个高度多样化的家族，是真足纲植物的祖先，本研究的结果将补充现有的记录蕨科孢子植物抗旱性的数据集。第二组研究将检查附生和陆生真足类孢子植物的耐旱性。实验将测试干旱诱导的空气进入、叶片膨胀损失点对水力破坏的抵抗力，并将这些数据与许多解剖和形态特征联系起来。最后，将对这组配子体的干燥耐受性进行补充研究。结果将在系统发育框架中进行分析，这将明确测试孢子体和配子体的相关性状进化。

Seed-free vascular plants such as ferns are the second most diverse plant lineage after the flowering plants, yet given their two-stage lifecycle and apparent intolerance of drought, the bases of their continued success are not completely understood. Recent studies have shown that both fern fronds (the vegetative generation) and fern gametophytes (the sexual generation) have evolved numerous strategies to cope with and recover from severe drought stress. This research investigates the water relations of both stages of the fern lifecycle to test the hypothesis that the evolution of traits typically related to drought tolerance promoted the expansion of ferns from largely moist, terrestrial habitats to drier, sunnier canopy habitats. The research will focus on drought tolerant traits of two recent fern lineages, which represent the bulk of tropical fern species diversity. Physiological, morphological and anatomical attributes will be examined across select species in the field and in the laboratory. This basic research will not only expand knowledge of the processes that shape biological diversity, but also potentially identify novel plant traits that could assist with the development of more drought resistant agricultural species. Students will receive international research experiences in Mexico and Costa Rica, and student/instructor exchanges will promote research collaboration. Outreach activities to the public will combine with non-profit collaborators at the Save the Redwood League and the Southern Madison Heritage Trust to illustrate the important role of ferns and other non-vascular plants in the ecology of natural plant communities. In order to determine whether drought stress exerts strong, convergent selection pressure on fern sporophytes and gametophytes, this research will examine the desiccation tolerance of gametophytes from numerous species in the Pteridaceae. The Pteridaceae are a hyper-diverse family of ferns that are ancestral to the Eupolypods, and the results from this study will complement an existing data set documenting drought tolerance in the Pteridaceae sporophytes. A second set of studies will examine the drought tolerance of epiphytic and terrestrial Eupolypod sporophytes. Experiments will test resistance to hydraulic failure by drought-induced air entry, leaf turgor loss points, and relate these data to numerous anatomical and morphological traits. Lastly, complementary studies looking at the desiccation tolerance of gametopytes in this group will be conducted. The results will be analyzed in a phylogenetic framework, which will explicitly test for correlated trait evolution in both sporophytes and gametophytes.