Data from: Linking life-history traits, ecology and niche breadth evolution in North American eriogonoids (Polygonaceae)

Macroevolutionary and microevolutionary studies provide complementary explanations of the processes shaping the evolution of niche breadth. Macroevolutionary approaches scrutinize factors such as the temporal and spatial environmental heterogeneities that drive differentiation among species. Microevolutionary studies, in contrast, focus on the processes that affect intraspecific variability. We combine these perspectives by using macroevolutionary models in a comparative study of intraspecific variability. We address potential differences in rates of evolution of niche breadth and position in annual and perennial plants of the Eriogonoideae subfamily of the Polygonaceae. We anticipated higher rates of evolution in annuals than in perennials owing to differences in generation time that are paralleled by rates of molecular evolution. Instead, we find that perennial eriogonoid species present greater environmental tolerance (wider climate niche) than annual species. Niche breadth of perennial species has evolved two to four times faster than in annuals, while niche optimum has diversified more rapidly among annual species than among perennials. Niche breadth and average elevation of species are correlated. Moreover, niche breadth increases more rapidly with mean species elevation in perennials than in annuals. Our results suggest that both environmental gradients and life history strategy influence rates and patterns of niche breadth evolution.

宏观进化（Macroevolutionary）与微观进化（Microevolutionary）研究为塑造生态位宽度（niche breadth）演化的各类过程提供了互补性阐释。宏观进化研究方法会细致考察驱动物种间分化的各类因素，例如时空环境异质性。与之相对，微观进化研究则聚焦于影响种内变异（intraspecific variability）的各类过程。本研究将两类视角相结合，在种内变异的比较研究中引入宏观进化模型。本研究针对蓼科（Polygonaceae）蓼亚科（Eriogonoideae）一年生与多年生植物的生态位宽度与生态位位置（niche position）的演化速率潜在差异展开探讨。基于与分子演化速率相匹配的世代时间差异，我们曾推测一年生植物的演化速率高于多年生植物。但本研究结果显示，多年生蓼亚科植物相较于一年生植物具有更强的环境耐受性，即拥有更宽泛的气候生态位（climate niche）。多年生植物的生态位宽度演化速率是一年生植物的2至4倍，而生态位最适值（niche optimum）在一年生植物类群中的分化速率则快于多年生植物类群。物种的生态位宽度与平均海拔存在相关。此外，多年生植物的生态位宽度随物种平均海拔升高的增长速率快于一年生植物。本研究结果表明，环境梯度与生活史策略均会对生态位宽度演化的速率与模式产生影响。