What is a natural taxon?
In taxonomy of the 20th Century (and probably even today) many might have said that a natural taxon is one that a competent taxonomist (or systematist) says it is! One might also argue that a natural taxon is one that can be defined and discovered by a set of operations. Neither of these philosophies of natural taxa is what an evolutionary biologists or phylogenetic systematists would interpret at being natural. Wiley (1981) refers to naturalness in science as carrying the connotation of “existing in nature, neither artificial nor man-made.” Thus, we may define natural taxon in the following way. Natural taxon an entity consisting of a single or two or more lineages existing in nature, either currently or historically, independent of the abilities of Homo sapiens to perceive it. Connotations associated with this definition (sensu Wiley, 1981): • Natural taxa exist via descent with modification whether or not there are systematists, or even Homo sapiens, around to perceive or name them.
