The diversity of lichen photobionts is not fully known. We studied here the diversity of the photobionts associated with Cladonia, a sub-cosmopolitan genus ecologically important, whose photobionts belong to the green algae genus Asterochloris. The genetic diversity of Asterochloris was screened by using the ITS rDNA and actin type I regions in 223 specimens and 135 species of Cladonia collected all over the world. These data, added to those available in GenBank, were compiled in a dataset of altogether 545 Asterochloris sequences occurring in 172 species of Cladonia. A high diversity of Asterochloris associated with Cladonia was found. The commonest photobiont lineages associated with this genus are A. glomerata, A. italiana, and A. mediterranea. Analyses of partitioned variation were carried out in order to elucidate the relative influence on the photobiont genetic variation of the following factors: mycobiont identity, geographic distribution, climate, and mycobiont phylogeny. The mycobiont identity and climate were found to be the main drivers for the genetic variation of Asterochloris. The geographical distribution of the different Asterochloris lineages was described. Some lineages showed a clear dominance in one or several climatic regions. In addition, the specificity and the selectivity were studied for 18 species of Cladonia. Potentially specialist and generalist species of Cladonia were identified. A correlation was found between the sexual reproduction frequency of the host and the frequency of certain Asterochloris OTUs. Some Asterochloris lineages co-occur with higher frequency than randomly expected in the Cladonia species.

地衣光生物素的多样性尚不完全清楚。我们在这里研究了与克拉多尼亚（Cladonia）相关的光生物多样性，克拉多尼亚是一种具有重要生态意义的亚世界性属，其光生物属于绿藻属紫草藻属。利用全球采集的223个石蕊标本、135种石蕊的ITS rDNA和肌动蛋白I型区域，对紫苑的遗传多样性进行了筛选。这些数据添加到 GenBank 中的可用数据中，被编译成一个数据集，该数据集包含172 个石蕊属物种中存在的总共 545 个紫草藻序列。发现了与克拉多尼亚相关的紫星绿藻的高度多样性。与该属相关的最常见的光生物谱系是A. glomerata、A. italiana和A. mediterranea。进行分区变异分析是为了阐明以下因素对光生物遗传变异的相对影响：真菌生物身份、地理分布、气候和真菌生物系统发育。研究发现，真菌生物特性和气候是紫星绿藻遗传变异的主要驱动因素。描述了不同星绿藻谱系的地理分布。一些谱系在一个或几个气候区域表现出明显的优势。此外，还对18种石蕊属植物的特异性和选择性进行了研究。鉴定出克拉多尼亚的潜在专科物种和通才物种。研究发现宿主的有性繁殖频率与某些紫星绿藻OTU 的频率之间存在相关性。一些紫星绿藻谱系共现的频率比克拉多尼亚物种中随机预期的要高。