Systematics

Article By:

Cracraft, Joel Department of Ornithology, American Museum of Natural History, New York, New York.

Last reviewed:January 2021

DOI:https://doi.org/10.1036/1097-8542.036000

The comparative analysis of living and fossil species, including their discovery, description, evolutionary relationships to other species, and patterns of geographic distribution. Because systematics involves crucial activities of describing and understanding the history of life, it is the primary science of biological diversity. In general, systematics can be divided into four major fields. Taxonomy, often equated with systematics, is the discipline concerned with the discovery, description, and classification of organism groups, termed taxa (singular, taxon). Classification is the clustering of species into a hierarchical arrangement according to some criterion, usually an understanding of their relationships to other species. Phylogenetic analysis, an increasingly important aspect of systematics, is the discovery of the historical, evolutionary relationships among species; this pattern of relationships is termed a phylogeny. The fourth component of systematics is biogeography, the study of species' geographic distributions. Historical biogeography examines how species' distributions have changed over time in relationship to the history of landforms, ocean basins, and climate, as well as how those changes have contributed to the evolution of biotas (groups of species living together in communities and ecosystems).

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