Data from: The roles of geography and environment in divergence within and between two closely related plant species inhabiting an island-like habitat

Aim: In island-like habitats, geographic isolation facilitates population and species divergence by constraining gene flow, while environmental isolation can enhance divergence. We tested the relative contribution of geographic and environmental isolation in genetic and phenotypic divergence within and between two species of the figwort Ameroglossum (Scrophulariaceae) inhabiting spatially isolated habitats, known as inselbergs.
Location: Borborema Plateau, north-eastern Brazil.
Methods: Multivariate models of redundancy (RDAs) and partial redundancy analyses (pRDAs) were used to partition the geographic and climate components of genetic variation in 48 microsatellite alleles, and phenotypic variation in 11 leaf and flower traits. We also used linear mixed-effect models (LMEs) to test independent associations of floral tube length variation among inselbergs with local pollinator phenotypes, climate and geography. In each approach, we analysed the data for each species separately and in pooled models for both species.
Results: RDAs revealed that genetic variation within and between the species of Ameroglossum was associated similarly with geography and climate. Phenotypic variation within A. manoel-felixii and between species was also associated similarly with geography and climate but, within A. pernambucense, phenotype was more strongly associated with climate. Linear mixed-effect models revealed that flower divergence in A. manoel-felixii was associated only with the bill length of local hummingbirds, whereas floral variation in A. pernambucense was associated with geography, bill length and climate. Only climate was associated with flower divergence between species.
Main conclusions: Genetic and phenotypic variation in Ameroglossum are associated with geographic and environmental isolation. These findings indicate a significant role of ecological factors shaping plant divergence among inselbergs, irrespective of their spatial distances.

研究目的：在类岛生境中，地理隔离通过限制基因流促进种群与物种分化，而环境隔离同样可强化分化过程。本研究以栖息于被称为岛状孤丘（inselbergs）的空间隔离生境中的玄参科美洲玄参属（Ameroglossum）两个物种为研究对象，旨在检验地理隔离与环境隔离在物种种内及种间遗传与表型分化中的相对贡献。
研究地点：巴西东北部博尔博雷马高原。
研究方法：采用冗余分析（RDAs）及偏冗余分析（pRDAs）多元模型，对48个微卫星等位基因的遗传变异以及11个叶部与花部性状的表型变异中地理与气候组分的贡献进行拆分。本研究同时采用线性混合效应模型（LMEs），检验不同岛状孤丘间花管长度变异与当地传粉者表型、气候及地理因素的独立关联。所有分析均分别针对两个物种单独开展，并针对两个物种构建合并模型进行分析。
研究结果：冗余分析结果显示，美洲玄参属两个物种种内及种间的遗传变异，均与地理及气候因素呈现相似的关联模式。曼努埃尔-费利克斯美洲玄参（A. manoel-felixii）的种内表型变异以及两物种间的表型变异，同样与地理及气候因素呈现相似关联；但在伯南布哥美洲玄参（A. pernambucense）种内，表型变异与气候因素的关联更为显著。线性混合效应模型结果显示，曼努埃尔-费利克斯美洲玄参的花部分化仅与当地蜂鸟的喙长相关，而伯南布哥美洲玄参的花部变异则与地理因素、喙长及气候因素均存在关联。两物种间的花部分化仅与气候因素相关。
主要结论：美洲玄参属植物的遗传与表型变异，均与地理隔离及环境隔离存在关联。本研究结果表明，无论岛状孤丘间的空间距离如何，生态因素均对岛状孤丘生境中植物的分化起到显著塑造作用。