Fundamentals of Evolution - Korzh O.P. - 2006

Part III. PATHWAYS OF LIFE EVOLUTION

Chapter 19. Main Trends in the Evolution of Living Organisms

The evolution of Multicellular Organisms is associated with the ability of Eukaryotic Cells to exhibit varying expressivity of hereditary information, as well as their capacity to function collaboratively. In higher plants, cells are interconnected by plasmodesmata and Cellulose layers produced by the cells themselves. Animal cells are integrated through the Extracellular matrix and via the adhesion of Plasma Membranes. One of the earliest milestones on the path to multicellularity was likely The Emergence of epithelium, in which cells are organized into layers that separate the internal environment of the Organism from the external one. Subsequent evolution proceeded toward generating an increasing variety of specialized cells and sophisticated Methods for coordinating their activity (vertebrate cells exhibit over 200 different specialization types).