Taxonomy (biology)

Taxonomy names and classifies organisms. Classification can organize known diversity and make comparisons useful, but ranks and names are not themselves evidence of ancestry. Phylogenetics infers that ancestry; a clade includes an ancestor and all its descendants. A shared feature such as lacking a cell nucleus need not identify an exclusive clade. The organism branch here organizes cell types for reading and is not a proposed phylogenetic tree. See OpenStax Biology 2e, 20.1: classification and evolutionary history.