苏铁类植物是现存较为古老的孑遗植物，也是种子植物中最原始的类群，其起源和演化一直是进化生物学的研究重点。中国仅有苏铁属（Cycas）植物分布，均为国家一级重点保护植物。在中国苏铁属植物研究上，总共有过57个种名，但IUCN的世界苏铁名录中仅认可25种，《Flora of China》仅记录16种。广西石灰岩地区是中国苏铁属植物多样化的地区之一，记载的类群多达24种，但一半以上的种类都没有得到IUCN认可。由于分类混乱，缺乏物种界定的理论依据，严重影响了该地区苏铁属植物的保护实践。本项目拟在对该地区的苏铁植物进行全面调查和采样的基础上，采用DNA片段和基于二代测序的RAD-Seq数据对该地区类群进行物种界定，并结合形态做分类修订，明确广西石灰岩地区苏铁属的种类，探讨其多样性的起源与演化；研究界定物种的遗传多样性、遗传结构及遗传变异的空间分布式样，探讨物种的濒危机制，为保护提供科学依据。

Cycads are extant relic plants which possess ancient lineages and are considered as the most primitive taxa among seed plants, and the studies on origin and evolution of Cycad plants have been the key questions in evolutionary biology. Within Cycads, only the genus Cycas is distributed in China and all of them have been listed as the first-grade national protected wild plants. Over the studies on Chinese Cycas plants, a total of 57 species names occurred in history, however, the IUCN World Cycad list only recorded 25 of them, and only 16 names were accepted in Flora of China. The limestone region of Guangxi is one of the Cycas diversity center in China where 24 Cycas taxa were described, while more than a half of them are not accepted by IUCN. On account of the disordering classification situation and no theoretical foundation being put forward for conservation guidelines, the protection practices of Cycas within the limestone region of Guangxi are seriously influenced. In this project, we are aiming to conduct throughout surveys and sampling on the limestone Cycas in Guangxi to clarify the species lineages as well as the origin and evolution of these species. Both traditional DNA markers and next generation sequencing based RAD-seq data are using to study the species delimitation and taxonomical revisions of the Cycas taxa from this region basing on wild investigations and morphological characters. For those successfully delimited species taxa, we are going to study the genetic diversity as well as the genetic structure to reveal the relationship between genetic diversity, structure and the current endangered status of them, which will offer ground conservation guidelines for the Cycas in the limestone region of Guangxi, China.