Date/Time
Date(s) - 10/03/2004
3:30 pm - 4:30 pm

Title: Evolution in Formation & Information in Evolution

Speaker: Dr. J.R. Stone

Institute: McMaster University
Department of Biology

Location: ABB 102

Description:

Two studies in Computational Biology will be presented, one involving shape change during evolution and the other involving information derived in constructing phylogenetic systematic classifications.

Evolution in Formation
A computer graphical model for evolving mollusc shell forms was used to test a geometric constraint hypothesis for the disjunct phenotypic distribution that is exhibited within the species-rich land-snail genus Cerion. By constructing a â??morphospace’ for Cerion and mapping into it graphically simulated forms, a shell size and shape continuum was produced. Therefore, the absence for particular shell forms in nature cannot be explained by geometric constraints. Two shell morphogenesis modes, which occur at extreme ranges in size (“dwarfs” and “giants”), were hypothesised previously to constitute exclusive routes for constructing elongated (“smokestack”) forms. Computer simulation revealed that multiple transformation routes are available; these routes are reversible geometrically and interconnect members in the shell form continuum. The possible pathways that were followed during evolution within this genus cannot be determined until an adequate phylogenetic hypothesis has been proposed.

Information in Evolution
Elementary equations from information theory were applied to the practices that are involved in phylogenetic systematic analyses. An equation that quantifies the information that is obtained by constructing classifications was derived. Given particular conditions, the information that is obtained increases monotonically with increasing taxa and, so, may be used directly as a comparative measure for species richness between sister groups. To exemplify the application, groups representing 11 phyla in the animal kingdom were analysed and the information that was obtained was compared. Speculative evolutionary explanations will be presented to elucidate the results.