David Houle : Approaching the evolution of novelty

I consider two kinds of biological novelty using shape of the Drosophila wing as a focal phenotype. Quantitative novelty is the evolution of more or less of the same elements already present in the ancestor, or evolution within one topological space. Qualitative novelty is gain of elements not present in the ancestor, or perhaps the loss of such elements, making a transition from one topological space to another. A quantitative genetic approach allows us to studying the major determinants of quantitative novelty, standing genetic variation and mutational variation. I will present measurements of both mutation and standing variation for a multivariate phenotype, the fly wing. Mathematical and statistical challenges in quantitative novelty involve the identification of subspaces within a topological space with genetic variation, and their relationship to the subspaces found in other samples. Qualitative novelty is easy to identify among species, but its evolution is difficult to study, as by definition it is absent in the ancestor. The process of development, where qualitatively different structures are progressively introduced during most life cycles, provides a framework to understand the evolution of novelty. Developmental studies show that continuous changes in gene expression precede transitions to a new shape topology. Gene expression state within a shape is more complex object that shape itself, adding dimensions that may allow us to identify regions of one shape topology that are neighbors to other topologies.

• Category: Mathematical Biology
• Duration: 01:14:51
• Date:  March 30, 2012 at 11:55 AM
• Views: 105
• Tags:   seminar, Mathematical Biology Seminar