Taxonomic and evolutionary studies in the genus Usnea(Parmeliaceae, lichenized Ascomycota) focusing on the symbiotic relationship with photobiont.

利用分子系统发育树分析了地衣属真菌生物和光生物的共生关系。真菌分支基本上由3个亚属和属内2个剖面组成。在亚属分类群的分支中也发现了几个分支。Usnea属的光生生物属于Trebouxia属的9个支系。大多数的真菌类群选择每个特定的光生物分支。然而，一些真菌分支具有相同的光生物分支。除了Usnea外，对其他地衣光生体的进一步研究表明，地衣的共生关系可能是由于栖息地内常见藻类的共享和选择，而不是由于藻类伙伴的严格合作或全球地理差异。

The symbiotic relationship between mycobiont and photobiont in the lichen genus Usnea was examined based on the molecular phylogenetic trees. Mycobiont clades were fundamentally consisted of 3 subgenera and 2 sections within the genus. Several clades were also found within the clades of infrageneric taxonomic groups. Photobionts of Usnea belong to 9 clades within the genus Trebouxia. Most of the infrageneric groups of the mycobiont select each particular clade of photobiont. However, some of mycobiont clades share a same photobiont clade. Further examinations of other lichen photobionts in addition to those of Usnea suggest that symbiotic relationship in lichens may be due to sharing and selection of common alga within the habitat rather than strict cospeciation or global geographical difference of algal partners.