DISSERTATION RESEARCH: Gametophyte Ecology: Consequences for the Distribution and Abundance of Tropical Ferns

蕨类植物在植物中是独一无二的，因为它们在生命周期中有两个截然不同的自由生活阶段。孢子体阶段是常见的带叶植物，它无性产生孢子，然后萌发形成配子体阶段。相比之下，配子体很小，很少被看到，但它是关键，因为它是有性繁殖，形成孢子体，完成蕨类植物的生命周期。蕨类孢子体可以将数百万个孢子散布到环境中，但很少有配子体存活下来完成整个生活史。尽管配子体阶段对蕨类植物的分布和丰度很重要，但我们对控制其生存和繁殖的因素知之甚少。这项研究的目的是了解在哥斯达黎加潮湿的森林中蕨类配子体的生存和繁殖的控制，在那里蕨类是生态系统的重要组成部分。将利用一系列观察研究和实验来确定不同物种的配子体对干旱、光照和养分有效性的反应如何不同，以及这些反应如何影响繁殖和孢子体的形成。本研究将对蕨类植物种群的管理和保护具有一定的应用价值。这项研究的更广泛影响包括支持一篇博士论文，开发将保存在La Selva生物站标本馆的大量标本，以及开发测量光合作用和养分吸收的新技术。

Ferns are unique among plants because they have two distinct, free-living stages in their life cycle. The sporophyte stage is the familiar frond-bearing plant, which asexually produces spores that germinate to form the gametophyte stage. The gametophyte, by contrast, is tiny and rarely visible, but it is key because it reproduces sexually to form the sporophyte and complete the life cycle of the fern. A fern sporophyte may disperse millions of spores into its environment, yet few gametophytes ever survive to complete the life cycle. Despite the importance of the gametophyte stage to the distribution and abundance of ferns, we know little about the factors that control its survival and reproduction. The goal of this research is to understand controls over survival and reproduction of fern gametophytes in the wet forests of Costa Rica, where ferns are an important component of the ecosystem. A series of observational studies and experiments will be used to determine how different species' gametophytes vary in their response to drought, light, and nutrient availability, and how these responses affect reproduction and the formation of sporophytes. This study will have application to the management and conservation of fern populations. The broader impacts of this research include support of a doctoral dissertation, development of a large collection of specimens that will be archived in the herbarium of the La Selva Biological Station, and the development of new techniques for measuring photosynthesis and nutrient uptake.