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，是仅次于开花植物的第二大物种，但考虑到它们的两个生命阶段和明显的对干旱的耐受性，它们持续成功的基础尚不完全清楚。最近的研究表明，蕨类植物叶片(营养世代)和蕨类配子体(有性世代)都进化出许多策略来应对和恢复严重的干旱胁迫。这项研究调查了蕨类植物生命周期两个阶段的水分关系，以检验这样一种假设，即典型的与抗旱有关的性状的进化促进了蕨类植物从主要潮湿的陆地生境扩展到更干燥、更阳光的树冠生境。这项研究将集中在最近的两个蕨类植物的耐旱特性上，这两个系代表了热带蕨类物种多样性的大部分。将在田间和实验室对选定的物种进行生理、形态和解剖属性的检查。这项基础研究不仅将扩大形成生物多样性的过程的知识，还可能确定有助于开发更耐旱的农业物种的新植物特征。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。面向公众的外展活动将与拯救红木联盟和南麦迪逊遗产信托基金的非营利性合作者相结合，以说明蕨类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会对蕨类植物的孢子体和配子体施加强大的、趋同的选择压力，本研究将对蕨类植物众多物种的配子体的脱水耐性进行研究。蕨科是一个超多样性的蕨类植物科，是真蕨类的祖先，这项研究的结果将补充现有的关于蕨科孢子植物耐旱性的数据集。第二组研究将考察附生和陆生真足类孢子体的耐旱性。实验将通过干旱诱导的空气进入、叶片膨大损失点来测试对水力故障的抵抗力，并将这些数据与许多解剖和形态特征联系起来。最后，将对这一组配子体的脱水耐受性进行补充研究。结果将在系统发育框架内进行分析，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.