Using tribe cariceae (cyperaceae) as a model system to test ecological and evolutionary theory

生物多样性及其因人类活动而造成的损失越来越受到生物学家的关注，了解生物多样性的起源，维持和分布可以帮助保护规划面对全球气候变化和人类活动水平。理解这一点的困难之一是，很难理清自然规律、历史偶然性和偶然事件的相对作用。 最近的研究在方法和范围上有所不同，从特定科属的系统发育，到种群的遗传结构，再到多样性热点的地理。我和我的学生研究这些问题的背景下，一个单一的大谱系的植物，部落Cariceae（莎草科），俗称莎草。苔草属是一个世界性的分布群，大多数种类分布于温带、寒带、北极、高山和亚热带地区，其生境沿着日照、湿度、海拔和营养的梯度变化。在一个单一的大，多样和广泛的分支内工作提供了一个无与伦比的系统来测试生态学和进化的几个领域的假设：1）与栖息地和地理范围有关的多样化和性状进化的模式; 2）当地适应和随机因素的相对重要性，如扩散到植物群落组装; 3）适应性辐射和特征进化对不同环境条件的反应; 4）物种丰富度和特有性模式，以指导保护优先事项。我们将继续使用DNA序列来重建这一群体的进化历史（进化史），并使用这一进化史来研究植物群落组装的进化限制，特别是在极端环境中。我们还将比较在北卡罗来纳州东部进化的苔草属平行谱系中功能性状的进化。美国和东亚，以了解在过去1500万年的独立进化中，这些特征之间的相互关系和进化顺序的限制。

Biodiversity and its loss due to human activities is an increasing concern to biologists and understanding the origin, maintenance, and distribution of biodiversity can help conservation planning in the face of global changes in climate and levels of human activity. One difficulty in achieving this understanding is that the relative roles of natural laws, historical contingency, and chance events are hard to disentangle. Recent studies vary in approach and in scope from the phylogeny of particular families and genera, to the genetic structure of populations, to the geography of diversity hotspots. My students and I study these issues in the context of a single large lineage of plants, tribe Cariceae (Cyperaceae), commonly known as sedges. This group includes the broadly distributed genus Carex with nearly 2000 species (among 10 largest genera, globally) and four smaller genera with more restricted distributions that are nested within it. The group has a cosmopolitan distribution with most species found in temperate, boreal, arctic, alpine, and subtropical regions in a variety of habitats that vary along gradients of insolation, moisture, elevation, and nutrition. Working within a single large, diverse and widespread clade provides an unparalleled system for testing hypotheses in several fields of ecology and evolution: 1) patterns of diversification and trait evolution in relation to habitat and geographic range; 2) the relative importance of local adaptation and stochastic factors like dispersal to plant community assembly; 3) adaptive radiation and character evolution in response to different environmental conditions; and 4) patterns of species richness and endemism to guide conservation priorities. We will continue using DNA sequences to reconstruct the evolutionary history (phylogeny) of this group and use this phylogeny to study the evolutionary constraints on plant community assembly, especially in extreme environments. We will also compare the evolution of functional traits in parallel lineages of Carex that have evolved in Eastern N. America and Eastern Asia to understand constraints on the order of evolution and correlations among these traits during the past 15 million years of independent evolution.