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Polymerization and oligomerization in foraminiferal evolution

Mikhalevich V. I.

Studia Geologica Polonica

2005

Vol. 124

117-142

The regularities of evolutionary development were studied so far mostly at a multicellular level in the Metazoa. The analysis of the morphologic development of some Protistan groups, mainly the Foraminifera, shows that the basic rules of evolutionary development such as Dogiel's (1929, 1954) concept on polymerization and oligomerization of the structures of the organism, leading to further differentiation and integration of these structures in their morphology and functions, can be seen in the Foraminifera as well. Concerning the usually minute dimensions of the foraminiferal cell, the processes of polymerization are more developed at this level of organization than the processes of oligomerisation. Polymerization represents at the same time the prerequisites for the subsequent processes of oligomerization and differentiation. In the foraminifera the main polymerized structures are the number of nuclei and the genomes inside the nuclei (polyploidy), the number of chambers, the number of apertural openings and elements of the inner apertural structures. The polymerized elements of the foraminiferal skeleton are subject to the process of oligomerization as well. As a consequence of the preceding polymerization and oligomerization, new organismic differentiated and integrative structures emerge: the embryonal specialized chambers, integrative structures of stolons, tunnels and channels, and integrative apertural systems. These represent a new level of polymerization, the multiplication of the organism systems. Thus these processes promote the transition to a new level of organization, open pathways to further evolutionary change, which gives the organism a higher degree of wholeness and a higher level of activity of its functions. The processes of polymerization and oligomerization are the major pathways of macroevolution. These take place in different foraminiferal groups independently and in parallel, their investigation helps to construct a natural taxonomic system.