Taxonomic sequence (also known as systematic, phyletic or taxonomic order) is a sequence followed in listing of
taxa
In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...
which aids ease of use and roughly reflects the evolutionary relationships among the taxa.
Taxonomic sequences can exist for taxa within any
rank
Rank is the relative position, value, worth, complexity, power, importance, authority, level, etc. of a person or object within a ranking, such as:
Level or position in a hierarchical organization
* Academic rank
* Diplomatic rank
* Hierarchy
* ...
, that is, a list of
families,
genera
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...
,
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriat ...
can each have a sequence.
Early biologists used the concept of "age" or "primitiveness" of the groups in question to derive an order of arrangement, with "older" or more "primitive" groups being listed first and more recent or "advanced" ones last. A modern understanding of evolutionary biology has brought about a more robust framework for the taxonomic ordering of lists. A list may be seen as a rough one-dimensional representation of a
phylogenetic tree
A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree showing the evolutionary relationships among various biological spec ...
. Taxonomic sequences are essentially
heuristic
A heuristic (; ), or heuristic technique, is any approach to problem solving or self-discovery that employs a practical method that is not guaranteed to be optimal, perfect, or rational, but is nevertheless sufficient for reaching an immediate ...
devices that help in arrangements of linear systems such as books and information retrieval systems. Since phylogenetic relationships are complex and non-linear, there is no unique way to define the sequence, although they generally have the more basal listed first with species that cluster in a tight group included next to each other.
[
The organization of field guides and taxonomic monographs may either follow or prescribe the taxonomic sequence; changes in these sequences are often introduced by new publications.][
]
References
Bibliography
*
* {{Citation , last=Hawthorne , first=W.D. , last2=Hughes , first2=C.E. , year=2008 , title=Optimising linear taxon sequences derived from phylogenetic trees – a reply to Haston ''et al.'' , journal=Taxon , volume=57 , issue=3 , pages=698–704 , name-list-style=amp , doi=10.1002/tax.573002 , doi-access=free
Sequence
In mathematics, a sequence is an enumerated collection of objects in which repetitions are allowed and order matters. Like a set, it contains members (also called ''elements'', or ''terms''). The number of elements (possibly infinite) is called ...