Complexity Forum: Thomas Fink (Institut Curie)
Speaker: Thomas Fink (Curie Institute)
Title: Is the theory of neutral evolution right?
The neutral theory of evolution states that the vast majority of mutations are selectively neutral (they do not affect fitness). This was put forth three decades ago, and it remains the conventional view that nearly all mutations preserve phenotype. The fraction of mutations in a population that are neutral is the phenotype robustness r. Just how high can r be? We prove, using spectral graph theory, that the robustness r is severely limited by the size s of its underlying neutral network. It means that robust phenotypes must have vast neutral networks, and that high values of robustness may not be biologically possible. We confirm our result by exact enumeration of neutral networks for short sequences, by random sampling for longer sequences, and using data from RNA molecules and the genetic code.
Lunch group: 2