Dimensions: Collaborative Research: Genome structure and adaptive evolution in peatmosses (Sphagnum): ecosystem engineers

泥炭苔类植物种类繁多，分布在世界各地，种类超过300种。在北半球的北部，它们主导着湿地，形成了广泛的泥炭地，其中蕴藏着种类繁多的微生物、其他植物和动物。由于泥炭(部分分解的植物材料)的堆积，这些泥炭地对水运动的区域模式以及大气中氮、二氧化碳和甲烷的全球循环产生了深远的影响。据估计，地球上近三分之一的土壤碳被泥炭地束缚住了，尽管这些栖息地只占陆地表面积的10%左右。这项研究的目的是以泥炭藓为模型，更好地理解DNA序列变异、植物性状和生态功能之间的关系。这项研究提供了一个独特的机会，将基因组成和变异与这些基因编码的植物性状联系起来，并研究这些植物性状是如何影响生态系统功能的。本科生、研究生和博士后研究人员将接受不同的基因组、进化、计算和生态学方法和分析方面的培训，包括合作机构之间的实验室交流。结果将通过实地课程和图文并茂的公众可访问的泥炭植物在线数据库广泛传播给公众。这项研究结合了广泛水平的系统发育学，广泛分布的泥炭藓物种的普通花园实验，以及全属范围的比较基因组学研究，以了解物种内发生的适应过程如何扩大到并解释世界范围内该属的多样性。将组装96个泥炭属物种的全基因组DNA序列，代表该属的全球范围。然后，这些数据将被用于重建物种之间的系统发育关系，并评估全属的基因组变异。对这些数据的分析将检验系统发育模式、分布范围、生态广度和重要生态表型性状变异之间的相关性。从北极到热带地区的麦粒泥炭草植株将跨越纬度梯度采集并在实验条件下生长，以评估光合作用对包括日长和温度在内的环境因素的响应，以及生理反应中的种群分化。将使用RNA测序来测量实验植物中的基因表达反应，以更好地了解局部生理适应的遗传基础。将汇集不同麦哲伦种群的全基因组DNA序列，以评估单个物种内基因含量的差异(泛基因组结构)。将这些种群水平的数据与横跨泥炭藓属物种的全基因组序列数据进行比较，将确定这些基因中有多少与其他泥炭藓物种共享。这些数据将被用来测试的一个具体预测是，广泛分布的物种在热带植物中可诱导的生理反应是否已经在热带泥炭藓物种中成为固定和构成的。

Peatmosses comprise a diverse group of plants with over 300 species distributed throughout the world. In northern parts of the Northern Hemisphere, they dominate wetlands and form extensive peatlands that harbor a broad diversity of microbes, other plants, and animals. Because of the build-up of peat (partially decomposed plant material), these peatlands have profound impacts on regional patterns of water movement, and the global cycling of atmospheric nitrogen, carbon dioxide, and methane. It is estimated that almost one third of the earth's soil carbon is bound up in peatlands even though these habitats account for only about 10% of the land surface area. The goals of this research are to use peatmosses as a model to better understand the connections between DNA sequence variation, plant traits, and ecological function. This research provides a unique opportunity to connect gene composition and variation to the plant traits encoded by those genes, and investigate how these plant traits affect ecosystem function. Undergraduates, graduate students and post-doctoral researchers will be trained in diverse genomic, evolutionary, computational, and ecological methods and analysis, including laboratory exchanges among the collaborating institutions. Results will be disseminated broadly to the public via field courses and an illustrated publically accessible, online database about peatmosses. This research integrates broad-level phylogenetics, common garden experiments of a widely-distributed Sphagnum species, and genus-wide comparative genomic studies to understand how adaptive processes occurring within species scale up to and explain diversification of the genus on a worldwide scale. Whole genome DNA sequences will be assembled for 96 Sphagnum species representing the worldwide range of the genus. These data will then be used to reconstruct phylogenetic relationships among species and assess genus-wide genomic variation. Analyses of these data will then test for correlations among phylogenetic patterns, distributional range, ecological breadth, and variation in ecologically important phenotypic traits. Plants of Sphagnum magellanicum, which occurs from arctic to tropical regions, will be collected across a latitudinal gradient and grown under experimental conditions to assess photosynthetic responses to environmental factors including day length and temperature, and population differentiation in physiological response. Gene expression responses in experimental plants will be measured using RNA sequencing to better understand the genetic basis of local physiological adaptation. Whole genome DNA sequences of different S. magellanicum populations will be assembled to assess variation in gene content within a single species (Pan genome structure). Comparing these population-level data with whole genome sequence data from species spanning the Sphagnum genus will identify how many of these genes are shared with other peatmoss species. One specific prediction these data will be used to test is whether inducible physiological responses in tropical plants of a widespread species have become fixed and constitutive in tropical Sphagnum species.