Taxonomy and Phylogeny Study Guide

A comprehensive set of vocabulary flashcards covering the anatomy of phylogenetic trees, classification systems, and taxonomic nomenclature rules.

Phylogenetic tree

A diagram used by scientists to show the evolutionary relationships among various biological species.

Taxon

A group of one or more populations of an organism or organisms seen by taxonomists to form a unit, such as a specific species or kingdom.

Parsimony

The principle that the simplest explanation that can explain the data is to be preferred, often used to determine the most likely phylogenetic tree.

Root

The point on a phylogenetic tree representing the most recent common ancestor of all the entities in the tree.

Evolutionary time

The dimension in a phylogenetic tree often represented by the length of the branches or the progression from the root to the tips.

Branches

The lines on a phylogenetic tree that represent evolutionary lineages over time.

Node

A point on a phylogenetic tree where a lineage splits, representing the common ancestor of the descendants.

Sister Taxa

Two lineages that are each other's closest relatives because they emerged from the same node.

Synapomorphy

A shared, derived character or trait that is present in an ancestral species and shared exclusively by its descendants.

Outgroup

A more distantly related group of organisms that serves as a reference group when determining the evolutionary relationships of the ingroup.

Monophyletic clade

A group that includes a single common ancestor and all of its descendants.

Paraphyletic clade

A group that includes a common ancestor and some, but not all, of its descendants.

Taxonomy

The branch of science concerned with the classification, description, identification, and naming of organisms.

Kingdoms

The second highest taxonomic rank, just below domain, used in the biological classification of organisms.

Domains

The highest taxonomic rank of organisms in the three-domain system of taxonomy.

Binomial Nomenclature

The formal two-part naming system for species where the genus is capitalized, the species is lower case, and both names are written in italics.

Dichotomous key

A scientific tool used to identify organisms based on a series of choices between alternative characteristics.