Convergent Evolution and Ecophysiological Differentiation in Chaparral Shrubs: A Comparative Analysis

加州的查帕拉和世界各地的类似群落在植物生态学作为一门科学的发展中发挥了关键作用。这些群落中远亲物种的生态相似性长期以来一直是趋同适应的典范。此外，物种间生态差异的研究在阐明与非生物胁迫和干扰相关的替代策略方面发挥了核心作用。生态变异的研究集中在两个方面：i)水分关系和耐旱性，与根深和栖息地分布有关；ii)与火灾后更新有关的生活史策略的对比。这项研究的第一个目标是通过对从加州北部到南部的三个地点的30多种植物进行广泛的比较研究，来检验光合作用特性、耐旱性和火灾再生特性之间的关系。该项目的第二个目标是将这些生态学研究与迅速扩大的植物物种间系统发育关系的知识结合起来，以测试这些物种之间的相似和不同是否代表了当地对查帕尔气候的适应，还是代表了后来导致当前群落聚集的古老特征。这个项目是第一次尝试评估大量的生理和生活史特征对木本植物物种功能群鉴定的贡献。功能基团的识别是理解不同植物群落共存机制的关键一步，也是评估不同物种对不断变化的火灾制度和其他环境条件的潜在反应的关键步骤。此外，该项目将最终测试长期存在的在类似牧羊人的社区中汇聚适应的范例。

The California chaparral and similar communities around the world have played a pivotal role in the development of plant ecology as a science. The ecological similarity of distantly related species in these communities has long served as a paradigmatic example of convergent adaptation. In addition, the study of ecological differences between species has played a central role in elucidating alternative strategies related to abiotic stress and disturbance. The study of ecological variation has focused on two features: i) water relations and drought tolerance, in relation to rooting depth and habitat distribution, and ii) contrasting life history strategies related to regeneration following fire. The first objective of this study is to examine the relationships between photosynthetic characteristics, drought tolerance, and fire-regeneration traits in a broad comparative study of over 30 species from three sites ranging from northern to southern California. The second objective of this project is to integrate these ecological studies with the rapidly expanding knowledge of phylogenetic relationships among plant species to test whether the similarities and differences among these species represent local adaptations to the chaparral climate, or older characteristics which then led to the assembly of the current community. This project represents the first attempt to assess the contributions of a large number of physiological and life-history traits to the identification of functional groups in woody plant species. The identification of functional groups is a critical step in understanding the mechanisms of coexistence in diverse plant communities, and in assessing the potential responses of different species to changing fire regimes and other environmental conditions. Furthermore, this project will finally provide a test of the long-standing paradigm of convergent adaptation in chaparral-like communities.