物种形成和适应机制是进化生物学和生态学的核心问题。落叶松是北半球寒温带、温带和高山及亚高山针叶林的主要组分和重要的造林树种，具有极高的生态和经济价值。中国是落叶松属物种分布最丰富的地区。传统上，该属根据形态分为落叶松组和红杉组。后者除北美两个种外，其余物种均分布在我国秦岭和喜马拉雅―横断山区及少数周边地区。由于生态适应性不同，落叶松在我国的地理分布遵循着“红杉组北不越秦岭，落叶松组南不过黄河”规律。由于快速辐射分化，红杉组物种遗传分化低，种间关系和进化历史仍不清楚，地理变异也有待研究。本项目拟基于转录组数据，利用系统发育重建和群体遗传学的方法，澄清红杉组物种的系统关系和进化历史，揭示红杉组物种的自然变异和物种形成机制。结合同质园（植物园）栽培的落叶松组物种的比较转录组分析，筛选与环境适应和生长节律相关的候选基因，通过在野生群体中的群体遗传学分析，阐明红杉组和落叶松组物种的适应性进化机制。

Speciation and adaptation is a fundamental issue in evolutionary biology and ecology. Larix, with unparalleled ecological and economical importance, is a prominent component of the boreal, montane and subalpine forests in the North Hemisphere and is the principal source of the world’s wood for pulp, paper and solid-wood products. Traditionally, Larix was divided into sect. Larix and sect. Multiserialis according to the morphological traits. China is the most larch species-rich region in the world. Because of the contrasting environmental adaptability, the geographical distribution of Larix in China follows the rule that Sect. Multiserialis never extends northwards over the Qin Ling Mountains and sect. Larix never passes southwards across Huang River. Species of sect. Multiserialis are mainly distributed in Qinling Mts. and Himalayas-Hengduan Mts., the well-known biodiversity hotspots in China and the world. Due to the rapid diversification of sect. Multiserialis, the phylogenetic relationships among species and the evolutionary history remain unresolved, and the spatial pattern of natural genetic variation is also needed to investigate. In this project, we will take advantage of the next generation sequencing technology to shed new insights into speciation processes, clarify the species relationships and evolutionary history of sect. Multiserialis and reveal the spatial patterns of natural variation of wild populations. Combined with the comparative transcriptome analysis of the cultivated species from sect. Larix, we will screen candidate genes for environmental adaptation and growth rhythm and then using population genetic analysis to test the patterns of these candidate genes in the wild populations and explore the evolutionary mechanisms of adaptation in Larix. This project would benefit the conservation and utilization of larch genetic resources and the study of speciation of conifers in Hengduan Mountains, the biodiversity hotspot in the world.