Dissertation Research: Phylogenetics of Neotropical Fern Genus, Jamesonia, and its Closest Relatives

小行星9801245 Jamesonia是一个主要分布在安第斯山脉的蕨类植物属，在蕨类植物中具有独特的营养和生态特征。这组高度修改的蕨类植物表现出一套形态特征，可能与极端的环境因素在新热带区pramo生态系统。 普拉莫一词通常指海拔3200至5000米的安第斯高地，位于森林之上，永久积雪以下。普拉姆和云雾森林生态系统中植物群的惊人多样性是安第斯山脉形成期间地质复杂事件的结果。Jamesonia和它最近的亲戚Eriosorus是两个密切相关的类群在新出现的栖息地进化和多样化的一个很好的例子。本研究的初步目标是阐明詹姆逊属及其近缘种的系统发育关系。 为了回答这个问题，将研究两个不同的系统发育水平：1）Taenitidoideae亚科的一个更高水平的进化（蕨科），基于叶绿体基因rbcL的形态特征和DNA序列数据，和2）Jamesonia和Eriosorus的低水平同源性，根据18- 26 S核核糖体DNA（nrDNA）内的内转录间隔区（ITS）的形态特征和序列数据，本研究的第二个目的是探讨这一群体演化的生态条件和地理背景。 将使用地理学和生态学数据的定量比较方法来推断上述生物多样性背景下的多样化进程。 Jamesonia和Eriosorus，在系统发育的框架内，异胚系列的比较研究，将有助于我们理解个体发育过程和形态多样化之间的关系。

9801245 Mishler Jamesonia is a mainly Andean genus of ferns that is unique among the ferns in its vegetative and ecological characteristics. This highly modified group of ferns exhibits a suite of morphological features perhaps related to the extreme environmental factors prevailing in Neotropical p ramo ecosystems. The term p ramo generally refers to Andean highlands, between 3200 and 5000 m altitude, located above the forest and below the permanent snow levels. The amazing diversity of the flora present in the p ramo and cloud forest ecosystems is the result of geologically complex events during the formation of the Andes. Jamesonia and its closest relative Eriosorus are a good example of two closely related taxa that evolved and diversified in a newly arisen habitat. The initial goal of this study is to clarify the phylogenetic relationships of Jamesonia and its closest relatives. To answer this question two different phylogenetic levels will be studied: 1) a higher-level phylogeny of the subfamily Taenitidoideae (Pteridaceae), based on morphological characters and DNA sequence data from the chloroplast gene rbcL, and 2) a lower-level phylogeny of Jamesonia and Eriosorus, based on morphological characters and sequence data of the internal transcribed spacers (ITS) within the 18-26S nuclear ribosomal DNA (nrDNA). The second goal of this study is to investigate the ecological conditions and biogeographic context of the evolution of this group. A quantitative comparative approach using biogeographic and ecological data will be used to infer processes of diversification in the context of the above phylogenies. Comparative studies on the heteroblastic series of Jamesonia and Eriosorus, within the phylogenetic framework, will be pursued to contribute in our understanding of the relationships between ontogenetic processes and morphological diversification.