Genetic variation and dispersal ecology of the lichen Erioderma pedicellatum in Newfoundland: recommendations for management of a globally rare species

Erioderma pedicellatum (Hue) P.M. Jørg is a globally rare and critically endangered lichen largely confined to the island portion of Newfoundland and Labrador. In 2002 the Boreal population was designated under the federal Species at Risk Act (SARA) as a species of "Special Concern", while the Atlantic population was listed as "Endangered". Under the provincial Endangered Species Act the lichen was designated as a "Vulnerable" species. This designation does not provide immediate protection for the lichen but requires the development of a management plan and periodic status assessment. Essential management baseline information on the species is lacking; especially on the ecology of the species as well as levels of genetic variability. This project attempts to answer key questions about the dispersal ecology of E. pedicellatum and identifies markers for analysis of genetic variation in Newfoundland and Labrador. Using the Internal Transcribed Spacer (ITS-I) of the ribosomal DNA (rDNA), two haplotypes were found among samples from Newfoundland and a single 62-year-old Swedish herbarium specimen. The common haplotype was found in both the Newfoundland samples and the Swedish sample. In addition through field research, this study describes for the first time the micro-ornamentation on the surface of E. pedicellatum spores and concludes through laboratory studies that the minute E. pedicellatum spores are actively discharged (<10 mm), can become trapped on the leg bristles or antennae of flying insects and may therefore be carried individually by these small animals. Given the high probability of an insect landing on an E. pedicellatum thallus and the shear abundance of insects in the boreal forest, our hypothesis of insects as dispersal vectors of spores is possible. We predict the potential number of insects carrying E. pedicellatum spores to be in the range of 129-161 over a 15 year period, given the calculated probability of insects landing on thalli, 4000-5000 incidences. This has important implications for forest management in E. pedicellatum habitat and further research should build on these findings by testing maximum distances spores travel in the average gap sizes of the Avalon forests, the periodicity of dispersal, and implementing harvesting /cutting block sizes to test the dispersal limitation of the species. These findings should be compared to the genetic variation of the species. This is the first study documenting the genetic variation of this rare species and the results provide significant, important information on the global population. We conclude that given the low genetic variation and the lack of variation between North American and European populations, that the global population is one evolutionary unit. This supports the IUCN designation of a globally endangered population.

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