Shape analysis of moss (Bryophyta) sporophytes: insights into land plant evolution

PREMISE OF THE STUDY: The alternation of generations life cycle represents a key feature of land-plant evolution and has resulted in a diverse array of sporophyte forms and modifications in all groups of land plants. We test the hypothesis that evolution of sporangium (capsule) shape of the mosses—the second most diverse land-plant lineage—has been driven by differing physiological demands of life in diverse habitats. This study provides an important conceptual framework for analyzing the evolution of a single, homologous character in a continuous framework across a deep expanse of time, across all branches of the tree of life. METHODS: We reconstruct ancestral sporangium shape and ancestral habitat on the largest phylogeny of mosses to date, and use phylogenetic generalized least squares regression to test the association between habitat and sporangium shape. In addition, we examine the association between shifts in sporangium shape and species diversification. RESULTS: We demonstrat...研究背景：世代交替的生活史是陆生植物演化的核心特征之一，由此催生了所有陆生植物类群中孢子体形态与特化修饰方式的丰富多样性。本研究旨在验证一项假说：作为陆生植物中物种多样性第二高的类群，苔藓植物的孢蒴（sporangium，亦称capsule）的形态演化，系不同生境下差异化生理需求驱动的结果。本研究为在跨越漫长演化时间尺度、覆盖生命之树所有分支的连续框架下，分析单一同源性状的演化提供了重要的概念框架。 研究方法：本研究基于目前已发表的最大规模苔藓植物系统发育树，重建祖先孢蒴形态与祖先生境，并采用系统发育广义最小二乘回归检验生境与孢蒴形态之间的关联。此外，本研究还探讨了孢蒴形态演化转变与物种分化速率之间的关联。 研究结果：本研究证实……