EPSRC Network on Evolvability in Biology & Software Systems

Evolvability, Genetics & Development in Natural and Constructed Systems: Abstracts of the EPSRC Evolvability Network Symposium

Tewin Bury Farm Hotel, Hertfordshire, England, UK
26-28 August 2003


University of Hertfordshire Computer Science Technical Report 389
C. L. Nehaniv, P. J. Bentley & S. Kumar (Editors)

An Evolutionary Scenario for the Origin of Flowers, the Goals

An Evolutionary Scenario for the Origin of Flowers, the Goals of Evo-Devo, and
What Has and Hasn't Happened

MICHAEL FROHLICH

The Natural History Museum, London, United Kingdom

M.Frohlich@nhm.ac.uk


To elucidate evolvability one may seek to determine what sorts of evolutionary events have occurred in evolution, and also what sorts have not occurred. Heterotopy, in which a structure changes position on an organism, has long been considered an event that almost never occurs - yet it may have been crucial in the evolutionary origin of flowers. The Mostly Male theory is the first theory of flower origins to be based on evidence from gene phylogenies, genetics, modern plant morphology and also on fossils. It suggests that flower organization derives more from the male structures of ancestral gymnosperms than from the female, and involves one instance of heterotopy to generate the precursor of the carpel, the most complex structure of the flower. They theory is now being tested; we do not yet know if it will be supported. The most interesting evolutionary innovations, typically recognized as creating major taxonomic groups, are likely to be the most difficult to elucidate, but may be the most informative regarding evolvability, because they bridge seeming discontinuities in organismal morphology. The new field of evo-devo may allow such innovations to be explained. I think the goal of evo-devo should be testable evolutionary scenarios, that explain the evolutionary events in as much detail as possible, in particular, to show the evolutionary trajectory, traversing a series of intermediate steps, each of which was evolvable. There is a multitude of questions that might be addressable in evo-devo. Why do some innovations appear to happen commonly in some groups, but rarely if ever in others? Why have some seemingly useful innovations never happened? Did change in the biotic or physical environments allow certain innovations in some epochs, but not in others? How important (or common) are large, discontinuous changes in phenotype, as opposed to small, incremental changes? How important is chance in the observed history of evolution? The coming decades will be scientifically very exciting.