UBI seminar (古澤研究室開催)
 Date: 14th Nov. (11/14) 2022 15:00-16:30 (JST)
 Place: Room 413 (Faculty of Science Bldg.1, Hongo campus) and Zoom
 Speaker: Dr. Tuan Pham (Niels Bohr Institute)
 Title:Double-replica theory for phenotype-genotype co-evolution

Abstract: The relationship between phenotype and genotype plays a crucial role in determining the function and robustness of biological systems. Here the evolution progresses through the change in genotype, whereas the selection is based on the phenotype, and genotype-phenotype relation also evolves. Theory for such phenotypic evolution remains poorly-developed, in contrast to evolution under the fitness landscape determined by genotypes. Here we study a statistical physics model for such phenotypic evolution, in which phenotypes are given by spin configurations, and genotypes are interaction matrix for spins to give the Hamiltonian, where the fitness depends only on the configuration of a subset of spins called target. We here address this problem with a novel approach that can describe the interplay between the fluctuation of genotype and that of phenotype by extending the replica theory for spinglasses to include two different replica species, spin-replica and coupling-replica, associated to phenotype and genotype, respectively. Within this framework we obtain a phase diagram of the evolved phenotypes against the noise and selection pressure. Robust fitted state is achieved under the intermediate level of noise (temperature), where robustness to noise and to genetic mutation are correlated. We also find a trade-off between maintaining a high fitness level of phenotype and acquiring a robust pattern of genes as well as the dependence of this trade-off on the ratio between the size of the functional (target) part to that of the remaining non-functional (non-target) one.