Functional morphology and phylogenetic testing within the framework of symecomorphosis.

Abstract

On the basis of the contrasting evolutionary patterns of the Teleostei and the "Chondrostei" the merit of phylogenetic testing is summarized as a non-arbitrary method for assessing the possible role of various designs in producing differential morphological diversity in different lineages. Arguments are presented for the recognition of a genealogical (reproductive, informational) and an ecological hierarchy. Various levels are proposed within hierarchies, because there are processes intrinsic to each level that are not reducible to those of lower levels or subsumed by higher levels. Mutual influences exist between successive levels within a hierarchy and possible interhierarchical mutual influences are hypothesized between organisms, demes, and avatars, and from the germ line to functional units. The term symecomorphosis is proposed to denote the balanced symmetry of the co-existing and mutually interdependent ecological and genealogical hierarchies. Symecomorphosis predicts that a disturbance in environmental systems can destroy this balance with profound effects on the genealogical hierarchy. Using the evolutionary differentiation of four lineages of air breathing teleosts as an example, it is demonstrated how the principle of symecomorphosis can be included in tests establishing a causal relationship between design and differential diversity among lineages.