Fungal-algal interactions inRamalina menziesiiand its associated epiphytic lichen community

Abstract

AbstractLichens are a fascinating example of a symbiotic mutualism. It is still uncertain which processes guide fungal-photobiont interactions, and whether they are random or of a more complex nature. Here, the fungal-algal interactions inRamalina menziesiiand co-occurring taxa are analyzed by using DNA sequences of the algal Internal Transcribed Spacer region (ITS), to investigate fungal-algal associations in juvenileR. menziesiiand allied species. Algal species were identified by a combination of BLAST searches, median-joining network analysis, and Bayesian phylogenetics. Fungal-algal networks were analyzed for nestedness, both at the species and haplotype level (fungal species vs. algal haplotypes), and the networks were inspected for evidence of compartmentalization. Bayesian phylogenetic trees indicated that the widespread green algaTrebouxia decoloransassociated withR. menziesii, as well as six other fungal species. Four additional fungal species interacted with four different species ofTrebouxia. Only in one out of ten samples were algal haplotypes shared with the nearest neighbours of juvenileR. menziesii. Fungal-algal species interactions were compartmentalized, while at the level of algal haplotypes, nestedness was found. This pattern is similar to the compartmentalization found in other intimately interacting mutualists.