Evolution by hybridisation. The influence of reticulate evolution on biosymmetrical patterns and processes in plants.

Natural hybridisation in plants is one of the most striking modes of evolution, when looking at the effects reticulation may have on patterns and processes of the evolutionary history of the affected system. Among other functional constraints, symmetry is regarded as a major factor of or for evolution. A loss of symmetry, that means origin of asymmetrical phenomena can in some cases be linked to environmental or genetic stresses, such as hybridisation. It has been shown that the discussion on reticulation and symmetrical evolution is strongly influenced by a zoocentric evolutionary view, but more focus is needed on the differences between the organisms subject to the study. Plant hybridogenic evolution with the subsequent possibility of polyploidisation and the consequent reduced homology is a completely different phenomenon compared to animal evolution. This article examines the role of symmetry for plant evolution by concentration on two topics: (a) spatial asymmetry on multiple levels caused by hybridisation, and (b) temporal asymmetry (changes of rhythms inherent to specific systems) as an effect of reticulation.