Classification and gene regulation of heterochronies and heterotopies as temporal and spatial evolutionary changes are considered. The intensity and duration of stem cell proliferation of a developing organism are connected with heterochronies and give rise to heterotopies. It is proposed that evolutionary emergence of new populations of stem cells (local embryomorphosis) is connected with heterotopies and heterochronies of gene expression, which support cell proliferation and temporarily suppress differentiation. The concept of modularity of evolutionary developmental biology and the theory of reproductive strategy naturally supplement each other and provide a better understanding of some ontogenetic changes in evolution. Developmental, morphological, and functional features of nematodes and vertebrates display alternative evolutionary trends with the predominance of progenesis and neoteny, respectively.
The intensity and duration of stem cell reproduc tion of a growing organism are connected with hetero chronies and give rise to heterotopies. The stem cell systems provide individual development, sexual and agamic reproduction, and survival of all multicellular organisms.
Common Design 