Sánchez-Baracaldo Patricia, Thomas Gavin H
School of Geographical Sciences, University of Bristol, Bristol, United Kingdom.
Department of Animal and Plant Sciences, University of Sheffield, Sheffield, South Yorkshire, United Kingdom.
PLoS One. 2014 Oct 23;9(10):e110618. doi: 10.1371/journal.pone.0110618. eCollection 2014.
The recent uplift of the tropical Andes (since the late Pliocene or early Pleistocene) provided extensive ecological opportunity for evolutionary radiations. We test for phylogenetic and morphological evidence of adaptive radiation and convergent evolution to novel habitats (exposed, high-altitude páramo habitats) in the Andean fern genera Jamesonia and Eriosorus. We construct time-calibrated phylogenies for the Jamesonia-Eriosorus clade. We then use recent phylogenetic comparative methods to test for evolutionary transitions among habitats, associations between habitat and leaf morphology, and ecologically driven variation in the rate of morphological evolution. Páramo species (Jamesonia) display morphological adaptations consistent with convergent evolution in response to the demands of a highly exposed environment but these adaptations are associated with microhabitat use rather than the páramo per se. Species that are associated with exposed microhabitats (including Jamesonia and Eriorsorus) are characterized by many but short pinnae per frond whereas species occupying sheltered microhabitats (primarily Eriosorus) have few but long pinnae per frond. Pinnae length declines more rapidly with altitude in sheltered species. Rates of speciation are significantly higher among páramo than non-páramo lineages supporting the hypothesis of adaptation and divergence in the unique Páramo biodiversity hotspot.
热带安第斯山脉近期的隆升（自上新世晚期或更新世早期以来）为进化辐射提供了广泛的生态机遇。我们检验了安第斯蕨类植物属Jamesonia和Eriosorus中适应性辐射和向新栖息地（暴露的高海拔帕拉莫栖息地）趋同进化的系统发育和形态学证据。我们构建了Jamesonia - Eriosorus分支的时间校准系统发育树。然后，我们使用最近的系统发育比较方法来检验栖息地之间的进化转变、栖息地与叶片形态之间的关联，以及生态驱动的形态进化速率变化。帕拉莫物种（Jamesonia）表现出与趋同进化一致的形态适应，以应对高度暴露环境的需求，但这些适应与微栖息地的利用有关，而非帕拉莫本身。与暴露微栖息地相关的物种（包括Jamesonia和Eriorsorus）的特征是每个叶状体有许多但短的羽片，而占据隐蔽微栖息地的物种（主要是Eriosorus）每个叶状体有很少但长的羽片。在隐蔽物种中，羽片长度随海拔下降得更快。帕拉莫谱系中的物种形成速率明显高于非帕拉莫谱系，这支持了独特的帕拉莫生物多样性热点地区适应和分化的假说。
