Systematics and Classification

Abstract

The systematist is interested in zoological uniqueness, in whole organisms, and systems. He determines the characters of taxa, their variation, and the biological causes for differences or shared characters. Classification, the delimitation, ordering and ranking of taxa, makes the organic diversity accessible to systematics at large and to other biological disciplines. The specific method of the systematist is comparison, not the experiment (Mayr 1969b).

The diversity of the organic world presents the systematist with numerous challenges at different levels of integration (Mayr 1974c). Inventory taking, at whatever level, is the first step and in taxonomy this means the delimitation of species taxa. The origin of diversity refers to the development of new genotypes (through mutation, recombination, etc.), new populations (through geographical variation, reduction of gene flow, etc.), new species and genera. Macroevolution is nothing but an extension of microevolution at the level of subspecies and species and a response to a previously vacant ecological zone. Real advances during the course of evolution were the widespread adoption of sexuality and multicellularity, and in plants vascularity and angiospermy. Each was a major step that provided an entirely new platform for the development of more evolutionary diversity. It is the study of diversity which has slowly undermined essentialism which dominated the study of nature for centuries.