Impacts of intraspecific variability and local adaptation on the ecophysiology of mosses: an example with Sphagnum magellanicum

BackgroundBryophytes are a diverse plant group and are functionally different from vascular plants. Yet, plant ecology theories and hypotheses are often presented in an inclusive term. The trait-based approach to ecology is no exception; largely focusing on vascular plant traits and almost exclusively on interspecific traits. Currently, we lack information about the magnitude and the importance of intraspecific variability to the ecophysiology of bryophytes and how these might translate to local adaptation--a prerequisite for adaptive evolution. MethodWe used transplant and factorial experiments involving moisture and light to ask whether variability in traits between morphologically distinct individuals of Sphagnum magellanicum from habitat extremes was due to phenotypic plasticity or local adaptation and the implications for the ecophysiology of the species. Key ResultsWe found that the factors that discriminated between the plant origins in the field did not translate to their ecophysiological functioning and the pattern of variability changed with the treatments, which suggests that the trait responses were due largely to phenotypic plasticity. The trait responses suggest that the need for mosses to grow in clumps where they maintain a uniform growth rate may have an overriding effect on responses to environmental heterogeneity, and therefore a constraint for local adaptation. ConclusionThe circumstances under which local adaptation would be beneficial in this plant group is not clear. We conclude that extending the trait-based framework to mosses or making comparisons between mosses and vascular plants under any theoretical framework would only be meaningful to the extent that growth form and dispersal strategies are considered.