Can fungal barcoding diagnose lichen species?

Reindeer, Rangifer tarandus L., are known to consume lichens as part of their winter diet, however within the Cairngorm herd, little is known of their ecological impact. Therefore, this study forms preliminary data for a larger, long-term project to assess the diet of the Cairngorm reindeer. Using sequence data of the ITS region, this study sought to: (1) determine the efficacy of species discrimination within the genera Cetraria Ach., Cladonia P. Browne, Ochrolechia A. Massal. and Umbilicaria Hoffm. through DNA barcoding and (2) to determine if a specific sub-region, ITS1 or ITS2 could act as a stand-alone barcode within lichenised fungi, which are potentially important in reindeer diet. Barcode gaps were found using uncorrected (p) distances in 62.5% of studied lichens, with Cladonia only producing a barcode gap in 37.5% of species. Of the sub-regions, ITS1 out-performed ITS2 with 77.6% of species being accurately discriminated, compared to 62.4%, however both regions were outperformed by full length ITS (78.4%), as expected. ITS performs well as a DNA barcode despite notable incongruence seen between the phenotype and genotype within Cladonia; thus, the use of an additional barcode such as cox1 or rpb2 is recommended for species level identification, although not essential as genus or section identifications are sufficient for assessing diet. The origin of this incongruence should be explored further as Cladonia contribute significantly to the biomass of the lichens in the Cairngorms, with UK BAP priority species Cladonia botrytes (K.G. Hagen) Willd. being found there. Incomplete lineage sorting or introgression are hypothesised as potential origins.