XII.6.2 Organism reproduction via single-cell stages facilitates the existence of organisms with very complex and highly integrated body structures
The development of an organism that also includes a single-cell stage has another important advantage compared to development occurring through separation of part of a multicellular organism and its supplementation to form a new organism.In the second case, the multicellular organism already has quite a complicated structure, where supplementing this part to make a whole organism would assume complicated dedifferentiation and reorganization of the existing structure (Dawkins 1982).Consequently, these types of vegetative reproduction through multicellular reproductive organs are limited in nature to only those types of organisms with quite simple and, where possible, decentralized body structure, encountered, e.g., in plants. Frequently, complicated and highly specialized reproduction organs, such as bulbs or tubers, are of key importance in this kind of reproduction.This mechanism of reproduction is not encountered in animal strains with complicated, highly integrated and centralized body structures and the development of a new individual can occur here only through a unique series of species-specific processes of ontogenesis, progressing from the stage of one cell through differentiation of embryonic tissues, organogenesis, to the formation of an individual capable of independent life.s