Complex sentence: Tuomi (1981) also provided a description on the theory of natural selection as a complex network of metatheory having specific theories, ancillary assumptions, and sub-theories being developed and originating within different research programs.
Split into simpler sentences: Tuomi (1981) described the theory of natural selection as a complex network of metatheory. This means that evolution is not a singular theory, but consists of specific theories, ancillary assumptions, and sub-theories that are being developed and originating within different research programs.