Specimen-based analysis of morphology and the environment in ecologically dominant grasses: the power of the herbarium

Herbaria contain a cumulative sample of the world’s flora, assembled by thousands of people over several hundred years. Recent advances in computation, DNA sequencing, and image manipulation have allowed us to capitalize on this resource. Using herbarium material, we conducted a species-level analysis of a major clade in the grass tribe Andropogoneae, which includes the dominant species of the world’s grasslands, from the genera Andropogon, Schizachyrium, Hyparrhenia, and other groups. We imaged 188 of the 250 available species of the clade, georeferenced the specimens, and extracted climatic variables for each. Using semiand fully automated image analysis techniques, we extracted spikelet morphological characters and correlated these with environmental variables. We are currently generating chloroplast genome sequences to correct for phylogenetic covariance and here present an analysis of a subset of 81 species, representing the power of this approach. In addition to taxonomic/phylogen...

植物标本馆（Herbaria）收藏了全球植物区系的累积馆藏样本，该样本由数千名研究者历经数百年的时间逐步汇集搭建而成。近年来，计算技术、DNA测序技术与图像处理技术的长足进步，使得我们得以充分利用这一珍贵资源。研究团队依托植物标本馆的馆藏材料，对禾本科须芒草族（Andropogoneae）内的一个主要演化支（clade）开展了物种级别的系统分析——该演化支包含全球草原的优势物种，涉及须芒草属（Andropogon）、裂稃草属（Schizachyrium）、黄背草属（Hyparrhenia）等多个类群。我们对该演化支中250个可获取物种里的188个完成了成像采集，为每份标本标定了地理坐标，并提取了各标本对应的气候变量数据。借助半自动化与全自动化的图像分析技术，我们提取了小穗（spikelet）的形态学特征，并将这些特征与环境变量进行了关联分析。目前我们正在构建叶绿体基因组序列，以校正系统发育协方差问题，本文则展示了针对该演化支中81个物种子集的分析结果，以此体现本研究方法的应用效能。除分类学与系统发育相关研究外