Dissertation Research: Investigating the Role of a Cryptic Life Stage in Fern Evolution and Community Assembly

蕨类植物代表着一个成功和多样化的谱系，由一个持续了数亿年的独特的生命周期统一起来。与苔藓植物或种子植物不同，蕨类植物的单倍体配子体和二倍体孢子体能够在很大程度上相互独立地发生，因此代表了不同的生态实体。目前关于蕨类生态学的知识几乎完全建立在更大、更容易观察到的孢子体阶段；相比之下，蕨类配子体由于体积小(通常为1厘米)和缺乏形态特征而被生态学家忽视，无法进行可靠的物种鉴定。然而，配子体代表着负责繁殖的有性阶段，因此对于理解蕨类生态学至关重要。DNA条形码方法的最新进展现在可以可靠地鉴定蕨类配子体，并为这一被忽视的植物生物学领域的研究开辟了新的途径。这项研究将利用法属波利尼西亚莫雷亚蕨类植物的广泛DNA条码库来鉴定野外采集的配子体，并在广泛的进化背景下比较蕨类配子体和孢子体的分布和生态适应性。该项目将为包括莫雷亚当地社区和美国大学生在内的多个群体带来好处，并将对蕨类植物保护产生重要影响。计划在莫雷亚的阿提亚社区中心开展外联活动，包括展示蕨类生物多样性的多语种博物馆。此外，这项研究的部分数据将由哈佛大学培训的本科生产生。通过增加博物馆藏品和描述新物种，人们将增加对生物多样性的了解。最后，对物种的调查？配子体分布将揭示分布格局，这将是设计濒危蕨类物种保护计划时需要考虑的重要因素。

Ferns represent a successful and diverse lineage, unified by a unique life cycle that has persisted for hundreds of millions of years. Unlike bryophytes or seed plants, the haploid gametophyte and diploid sporophyte of ferns are capable of occurring largely independent of one another, and thus represent distinct ecological entities. Current knowledge of fern ecology is based almost exclusively on the larger, easily observable sporophyte stage; fern gametophytes in contrast have been mostly ignored by ecologists due to their small size (typically 1 cm) and lack of morphological characters for reliable species identification. The gametophyte represents the sexual phase responsible for reproduction, however, and is thus critically important to understanding fern ecology. Recent advances in DNA barcoding methods now allow for the reliable identification of fern gametophytes, and have opened new avenues for research into this neglected area of plant biology. This study will leverage an extensive DNA barcode library of the ferns of Moorea, French Polynesia to identify field-collected gametophytes and compare the distribution and ecological adaptations of fern gametophytes and sporophytes in a broad evolutionary context. This project will provide benefits to multiple groups including both the local community on Moorea and university students in the U.S., and will have important implications for fern conservation. Outreach activities including a multilingual museum display on fern biodiversity are planned for the Atitia community center on Moorea. In addition, data for this research will be partially generated by undergraduates trained at Harvard University. Knowledge of biodiversity will be increased by adding to museum holdings and describing new species. Finally, investigations into species? gametophyte distribution will reveal distribution patterns that will be important to consider when designing conservation programs for endangered fern species.