Comparing Trebouxia diversity in lichen genera sympatric with the Niebla species complex.

Lichens are one of the most successful mutualisms on Earth. The ecology and distribution of lichen symbionts likely influences their association and genetic structure . Two sister genera of lichenized fungi Niebla and Vermilicinia are endemic to the fog deserts on the west coast of North America. Species of Trebouxia, a genus of green algae found worldwide, are the associated photobiont partners to the Niebla/Vermilicinia species complex. Recent work demonstrated that Niebla and Vermilicinia are highly specific for only a few closely related Trebouxia molecular species (OTUs). This project examines the diversity and broad specificity of algae with lichen forming fungal genera that are sympatric to Niebla and Vermilicinia to understand if the narrow associations seen previously in this species complex is due to limited photobiont availability. We hypothesize that sympatric lichen genera will have greater diversity of Trebouxia than is present in Niebla/Vermilicinia. ITS rDNA sequence data were collected from over 100 specimens of Niebla/Vermilicinia and sympatric lichens collected from a region of California. Previously obtained Niebla/Vermilicinia sequences from Morais and Muscavitch (unpublished) and published algal sequences from Ramalina were also analyzed. A total of 15 Trebouxia OTUs were found in the lichens examined, four of which are phylogenetically distinct and potentially novel species. In contrast, only four very closely related Trebouxia OTUs were found with Niebla/Vermilicinia. These results support our hypothesis that diverse photobionts are readily available in the environment and that the Niebla species complex, and sympatric fungal genera, may be selective in their photobiont partners