Área de Biodiversidad y Conservación, Departamento de Biología y Geología, Universidad Rey Juan Carlos 28933 Móstoles, Madrid, Spain.
Am J Bot. 2010 Feb;97(2):216-23. doi: 10.3732/ajb.0900064. Epub 2010 Jan 5.
Disjunct species distributions may result from a combination of geologic events and long-distance dispersal. The foliose lichen species complex Leptogium furfuraceum-L. pseudofurfuraceum has an intercontinental disjunction pattern. Populations of this species complex are found in western North America, southern South America, Africa, and southern Europe. We conducted a phylogenetic study to reconstruct the biogeographic history of this species complex using two ribosomal genes (ITS and LSU) and a protein-coding gene (partial RPB2). Results indicated that the complex comprises four geographically restricted genetic lineages. A sister relationship was found between populations from the same hemispheres, incongruent with previous data derived from morphological characteristics and geographical classification schemes. Incorporating Bayesian ancestral area reconstruction and Bayesian divergence time estimation, we proposed an evolutionary hypothesis for the species complex. The results suggested that processes of biotic expansion via transoceanic dispersal were responsible for the species divergence and distribution patterns observed today. This study also expands the view that cryptic speciation is not a rare phenomenon among fungi and lichens.
隔离种的分布可能是地质事件和长距离扩散的综合作用的结果。叶状地衣物种复合体 Leptogium furfuraceum-L. pseudofurfuraceum 具有洲际间断模式。该物种复合体的种群分布在北美西部、南美南部、非洲和南欧。我们进行了一项系统发育研究，使用两个核糖体基因（ITS 和 LSU）和一个蛋白质编码基因（部分 RPB2）来重建该物种复合体的生物地理历史。结果表明，该复合体由四个地理上受限的遗传谱系组成。来自同一半球的种群之间存在姐妹关系，与先前基于形态特征和地理分类方案得出的数据不一致。结合贝叶斯祖先区重建和贝叶斯分歧时间估计，我们提出了该物种复合体的进化假说。结果表明，通过跨洋扩散的生物扩张过程导致了今天观察到的物种分化和分布模式。这项研究还扩展了这样一种观点，即隐种形成在真菌和地衣中并不是一种罕见的现象。
