Computer simulation of the ontogeny of organisms with different types of symmetry

Abstract

The ontogeny of multicellular organisms is based on self-assembly of ordered structures due to coherent behavior of cells, each of which is basically “programmed” in the same way. All embryonic cells follow the same set of rules encoded in the structure of a gene regulatory network (GRN), which in its turn is encoded in the genome. This principle formed the basis for the Evo-Devo software designed by the authors for modeling the ontogeny of multicellular organisms. Modeling revealed the absence of unambiguous correlation between the type of symmetry of the organism and the complexity of GRNs that are needed to produce such symmetry. The developmental evolution of symmetry can occur without increasing complexity of the developmental program. However, the complexity of GRNs should increase in order to make the phenotype more robust, stable and ordered. This conclusion is concordant with Schmalhausen’s concepts concerning the formative role of stabilizing selection. Selection for more robust phenotype results in the development of additional regulatory mechanisms based on negative feedback, a process that necessarily implies the increase in complexity of the genetic developmental program. New elements of GRNs, in their turn, open new paths for evolutionary change.