Phylogeography and speciation of lichens on a background of slow genetic drift and incomplete lineage sorting

地衣是研究真菌种群历史和物种形成的完美模型，因为它们形成了划分良好的个体菌体。真菌的分布面积大多大于维管植物的分布面积，并且经常发生洲际断裂。我们正在进行的地衣种群结构和物种形成的研究表明，这些分布区域是范围破碎化而不是长距离分散的结果。遗传漂变显然是缓慢的，亲缘物种之间的谱系分选往往是不完整的。这就提出了一个问题，即异域范围破碎化在地衣物种形成中起什么作用。我们将使用多个DNA序列来研究一组形态相似的地衣与北美-欧洲分离。基于单倍型网络，我们希望解决该群体的系统地理学问题，并测试不同大陆种群之间的谱系分类是否早于物种的形成。我们将使用基于形态属性的贝叶斯分类将样本划分为类，并在单倍型网络上测试这些贝叶斯分类群与系统发育进化枝之间的关联。

Lichens represent perfect models to investigate population history and speciation of fungi because they form well-delimited individual thalli. The distributional areas of fungi are mostly larger than those of vascular plants and intercontinental disjunctions are frequent. Our ongoing studies on population structure and speciation within lichens indicate that these distributional areas are the result of range fragmentation rather than long distance dispersal. Genetic drift is apparently slow and lineage sorting between closely related species often incomplete. This raises the question what role allopatric range fragmentation plays in lichen species formation. We will use multiple DNA sequences to investigate a group of morphologically similar lichens with a North American-European disjunction. Based on haplotype networks we want to resolve the phylogeography of the group and test whether lineage sorting between populations on different continents predates the formation of species. We will use Bayesian classification based on morphological attributes to separate our sample into classes and test the association between these Bayesian taxa and phylogenetic clades on haplotype networks.