Final Report Summary - SELECTIONINFORMATION (Limits to selection in biology and in evolutionary computation)
The project focussed on the factors that limit natural selection: lack of recombination, interaction between genes, and spatial subdivision. Progress was made by combining several techniques: multilocus algebra, branching processes, an analogy with statistical mechanics, and a new model for population structure. This analysis was applied to biological and computational problems in parallel, focusing on how recombination aids selection; how interactions between gens (epistasis) may evolve to facilitate adaptation; and how selection acts in structured populations subject to frequent extinction and recolonisation. Methods were developed for analyzing DNA sequence data, and applied to diverse datasets.
The work covered a wide range, but key results include showing that:
• The rate of accumulation of favourable mutations is ultimately limited by recombination.
• Whether a species can adapt to a steep environmental gradient depends on two parameters – the steepness of the gradient relative to the strength of selection, and the strength of selection on each gene, relative to random fluctuations.
• The stochastic dynamics of high-dimensional systems can be accurately approximated by just a few macroscopic variables, using an analogy with thermodynamics.
• The size of a gene regulatory network is limited by crosstalk between its components, and the specificity of the recognition sequences.
• Complex models of population structure can be efficiently inferred from whole-genome data.
• The “infinitesimal model” represents complex quantitative traits, even in the presence of gene interactions.
• Evolutionary algorithms from computer science and models of natural populations can be represented in the same mathematical framework.