3  Thesis aim

These studies provide emerging evidence that genetic variation within a foundation species can influence a dependent community. Investigations linking the genetics of foundation species with dependent organisms may provide a powerfully integrative framework in community ecology. This thesis extends previous work to a new model system, by considering the effect of host tree genetic structure on cryptogamic epiphytes – an important component of forest biodiversity and ecosystem function in temperate and boreal ecosystems. A single study has provided evidence that a particular aspect of the phenotype, bark texture, influenced the distribution and abundance of a single, dependent epiphyte species (Lamit et al. 2011). The challenge remaining is to demonstrate not only that genetic variation within a foundation species can influence the community of dependent species, but also to demonstrate how variation in the phenotype of the foundation species is translated into differences in community composition of dependent organisms. This is the major objective of this thesis.

Lamit, L J, M A Bowker, L M Holeski, R R Næsborg, S C Wooley, M Zinkgraf, R L Lindroth, T G Whitham, and C A Gehring. 2011. “Genetically-Based Trait Variation Within a Foundation Tree Species Influences a Dominant Bark Lichen.” Fungal Ecology 4 (1): 103–9. https://doi.org/10.1016/j.funeco.2010.09.007.