The Andean uplift is one of the major orographic events in the New World and has impacted considerably the diversification of numerous Neotropical lineages. Despite its importance for biogeography, the specific role of mountain ranges as a dispersal barrier between South and Central American lowland plant lineages is still poorly understood. The swan orchids (Cycnoches) comprise ca 34 epiphytic species distributed in lowland and pre-montane forests of Central and South America. Here, we study the historical biogeography of Cycnoches to better understand the impact of the Andean uplift on the diversification of Neotropical lowland plant lineages. Using novel molecular sequences (five nuclear and plastid regions) and twelve biogeographic models, we infer that the most recent common ancestor of Cycnoches originated in Amazonia ca 5 Mya. The first colonization of Central America occurred from a direct migration event from Amazonia, and multiple bidirectional trans-Andean migrations between Amazonia and Central America took place subsequently. Notably, these rare biological exchanges occurred well after major mountain building periods. The Andes have limited plant migration, yet it has seldom allowed episodic gene exchange of lowland epiphyte lineages such as orchids with great potential for effortless dispersal because of the very light, anemochorous seeds.
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机译:安第斯山脉隆升是新世界的主要地形事件之一,已极大地影响了许多新热带世系的多样化。尽管它对生物地理学很重要,但人们仍然不了解山脉作为南美和中美洲低地植物谱系之间的传播屏障的特定作用。天鹅兰花(Cycnoches)包含约34种附生物种,分布在中美洲和南美洲的低地和山地前森林中。在这里,我们研究了Cycnoches的历史生物地理学,以更好地了解安第斯山脉隆升对新热带低地植物谱系多样性的影响。使用新的分子序列(五个核和质体区域)和十二个生物地理模型,我们推断Cycnoches的最新共同祖先起源于Amazonia ca 5 Mya。中美洲的第一次殖民化是由亚马逊河的一次直接迁移事件引起的,随后亚马逊河和中美洲之间发生了多次双向安第斯山脉跨境迁移。值得注意的是,这些罕见的生物交换发生在主要的山区建设时期之后。安第斯山脉的植物迁移受到限制,但由于极轻的,有绒毛的种子,它很少允许低地附生植物谱系(如兰花)发生偶发性基因交换,而兰花具有很容易散布的潜力。
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