Jiménez-Mejías Pedro, Benítez-Benítez Carmen, Fernández-Mazuecos Mario, Martín-Bravo Santiago
Department of Molecular Biology and Biochemical Engineering, Universidad Pablo de Olavide, Seville, Spain.
Department of Biodiversity and Conservation, Real Jardín Botánico (RJB-CSIC), Madrid, Spain.
PLoS One. 2017 Dec 27;12(12):e0189769. doi: 10.1371/journal.pone.0189769. eCollection 2017.
Plants growing in high-mountain environments may share common morphological features through convergent evolution resulting from an adaptative response to similar ecological conditions. The Carex flava species complex (sect. Ceratocystis, Cyperaceae) includes four dwarf morphotypes from Circum-Mediterranean mountains whose taxonomic status has remained obscure due to their apparent morphological resemblance. In this study we investigate whether these dwarf mountain morphotypes result from convergent evolution or common ancestry, and whether there are ecological differences promoting differentiation between the dwarf morphotypes and their taxonomically related large, well-developed counterparts. We used phylogenetic analyses of nrDNA (ITS) and ptDNA (rps16 and 5'trnK) sequences, ancestral state reconstruction, multivariate analyses of macro- and micromorphological data, and species distribution modeling. Dwarf morphotype populations were found to belong to three different genetic lineages, and several morphotype shifts from well-developed to dwarf were suggested by ancestral state reconstructions. Distribution modeling supported differences in climatic niche at regional scale between the large forms, mainly from lowland, and the dwarf mountain morphotypes. Our results suggest that dwarf mountain morphotypes within this sedge group are small forms of different lineages that have recurrently adapted to mountain habitats through convergent evolution.
生长在高山环境中的植物可能会通过趋同进化共享一些共同的形态特征，这种趋同进化是对相似生态条件的适应性反应所导致的。黄苔草物种复合体（苔草属，莎草科）包括来自环地中海山区的四种矮化形态类型，由于它们明显的形态相似性，其分类地位一直不明确。在本研究中，我们调查了这些矮化山地形态类型是趋同进化还是共同祖先的结果，以及是否存在生态差异促进了矮化形态类型与其分类学上相关的大型、发育良好的对应类型之间的分化。我们使用了nrDNA（ITS）和ptDNA（rps16和5'trnK）序列的系统发育分析、祖先状态重建、宏观和微观形态数据的多变量分析以及物种分布建模。发现矮化形态类型种群属于三个不同的遗传谱系，祖先状态重建表明有几个从发育良好到矮化的形态类型转变。分布建模支持了主要来自低地的大型形态类型与矮化山地形态类型在区域尺度上气候生态位的差异。我们的结果表明，这个莎草类群中的矮化山地形态类型是不同谱系的小型形态，它们通过趋同进化反复适应了山地生境。
