The hierarchy and combinatorial space of characters in evolutionary systematics

Abstract

In this paper, the Linnaean hierarchy is discussed as the taxonomic model for the evolutionary differentiation of the earth’s biota. This model allows us to understand why a number of ideas and arguments in the evolutionary theory are unfortunate. Among these is the idea of a linear ladder of nature («scala natura»). The arguments about species constancy versus species variability, natural species versus «artificial» higher taxa, a single type of animals versus multiple types, as well as about the connection versus disconnection of microevolution and macroevolution are meaningless. Two kinds of phylogeny are considered. The first reflects the appearance of new characters in the course of evolution, and their sequence provides the nesting hierarchy of groups. The second reflects the appearance of new character states and provides a basis for the diversity of taxa at each hierarchical level. The taxonomic hierarchy is an embodiment of the first kind of phylogeny and does not require the tracing of ancestors and descendants along the lines of character development. Character ranking and the improvement of a tentative taxonomic hierarchy with the help of a posteriori weighting of differences are discussed. The method of character weighting leads to the construction of prognostic combinatorial arrangements that can predict the existence of organisms with certain character state combinations at each hierarchical level. The drawbacks of cladistic methodology, especially the «synapomorphy principle», the «dichotomy principle», and the monophyly «definition» through the internal composition of groups, are noted. It is pointed out that these principles only lead to the creation of heterogeneous groups and wrong character ranking.