How Can Plants Choose the Most Promising Organs? - Communication in Plants: Neuronal Aspects of Plant Life - page 62

the development of varied biological patterns. The mature stomata of San-
sevieria are more orderly or predictably spaced than the early, reversible
stages of stomata initiation (Kagan and Sachs 1991). “Neural Darwinism”
is a mechanism by which appropriate nerve connections are selected from
excess alternatives (Edelman 1987). Within cells, microtubules are main-
tained according to functional roles that are established after they have
been formed (Kirschner and Mitchison 1986).
It may be useful to consider the adaptive significance of the generation
of tree form by developmental selection rather than strict programs. Com-
petition between branches requires the wasteful development of structures
that are not maintained. There is no doubt that dead branches below trees
represent considerable organic material. Yet these branches did carry out
photosynthesisforaslongastheywereproductiveandresourcessuchas
bound nitrogen can be withdrawn from dying plant organs (Habib et al.
1993). Losses of substrates could be balanced by the advantages of grad-
ual selection, in which information about the value of an existing branch
feeds back to its survival and further development. This testing of varied
possibilities could provide for a robust outcome.
A major advantage of developmental section may be in its relation to
plasticity. It is possible that in a predictable, ideal world strict programs
could result in superior biological forms. The real world, however, is far
from predictable. In the case of trees, the presence of competing neigh-
bors, damage due to herbivores and parasites and possible local failures
in the development of the plant itself require a pronounced developmen-
tal plasticity. Developmental selection uses the very same processes and
genetic information to generate form and to insure plastic responses to un-
predictable conditions (Sachs 2002). This parsimony might have adaptive
significance both because simpler developmental systems are required and
because the various component are all optimally integrated.
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