Setting the evolutionary timeline: Tillandsia landbeckii in the Chilean Atacama Desert

In the Chilean Atacama Desert Tillandsia landbeckii Phil. is forming a unique vegetation type known as Tillandsia lomas. This vegetation consists in its typical configuration of one single vascular plant species only. The species forms regular linear structures in a sloped landscape and is largely depending on sand movement and fog occurrence as dominant source of water supply. Without developing a typical root system there are also few other terrestrial Tillandsia species growing on bare sand in Chile and Peru such as T. marconae Till & Vitel, T. virescens Ruiz & Pavon, T. purpurea Ruiz & Pavon or T. latifolia Mayen. Although phylogenetic evidence is limited, convergent evolution of this unique growth behavior is evident. The Atacama Desert is one of the oldest hyperarid areas globally alongside the Namib. The predominantly arid and hyper-arid climate exists since the Early Miocene, which raises the question about timing of T. landbeckii evolutionary history. Our study highlights the onset of diversification in T. landbeckii and demonstrates also subsequent secondary genetic contact with T. purpurea during Late Pleistocene using whole plastome DNA sequence data.

在智利阿塔卡马沙漠中，兰贝克铁兰（Tillandsia landbeckii Phil.）形成了一种被称为铁兰雾灌丛（Tillandsia lomas）的独特植被类型。该植被的典型组成仅包含单一维管植物物种。该物种在坡地景观中形成规整的线性结构，其生存主要依赖沙丘移动与雾露作为核心供水来源，且未发育典型根系。在智利与秘鲁的裸沙生境中，同样存在少数其他陆生铁兰属物种，包括T. marconae Till & Vitel、T. virescens Ruiz & Pavon、紫花铁兰（T. purpurea Ruiz & Pavon）以及T. latifolia Mayen。尽管系统发育证据较为有限，但这种独特生长模式的趋同演化特征已十分显著。阿塔卡马沙漠与纳米布沙漠同为全球最古老的超干旱区域之一，该区域的干旱与超干旱气候自中新世早期便已形成，这引发了关于兰贝克铁兰演化历程时间节点的研究疑问。本研究借助全质体基因组DNA序列数据，明确了兰贝克铁兰的物种分化起始时间，并证实其在晚更新世时期与紫花铁兰发生了后续的次级遗传交流。