A Conflict Between Two Evolutionary Levels in Trees

Due to the lack of germ line segregation in plants, it is possible to consider plant evolution (but not the evolution of most animals) as being composed of two evolutionary levels: s work, a case of aconflict between these two levels is studied. The dynamics of a mutation, which is advantageous on the branch level but harmful for the whole tree, are discussed for a one-locus two-allele model. Several cases are considered: dominant, partially dominant, and haploid. Necessary and sufficient conditions for fixation of such a mutation are found. The model predicts that as the longevity of a tree species increases, the trees are expected to be more strongly shifted from their optimal growth-to-reproduction ratio towards growth, and resource allocation between branches and other tree parts is expected to be shifted in favor of the branches. Traditional approach, considering the second level only, is justified as a limit case for short longevity.