a scientific discipline focused on classifying organisms and determining their evolutionary relationships
A taxonomic category above the species level, designated by the first word of a species two-part scientific name
(1) A taxonomic category above the kingdom level. The three domains are Archaea, Bacteria, and Eukarya. (2) An independently folding part of a protein.
a branching diagram that represents a hypothesis about the evolutionary history of a group of organisms
System of classification of organisms based on evolutionary relationships: Only groups that include a common ancestor and all of its descendents are named.
the representation on a phylogenetic tree of the divergence of two or more taxa from a common ancestor. Most of these are shown as dichotomies, in which a branch representing the ancestral lineage splits into two branches, one for each of the two descendant taxa
Groups of organisms that share an immediate common ancestor and hence are each other's closest relatives.
Describing a phylogenetic tree that contains a branch point (typically, the one farthest to the left) representing the last common ancestor of all taxa in the tree.
In a phylogenetic tree, a branch point from which more than two descendant taxa emerge. This indicates that the evolutionary relationships among the descendant taxa are not yet clear.
similarity between two species that is due to convergent evolution rather than to descent from a common ancestor with the same trait
Similar (analogous) structure or molecular sequence that has evolved independently in two species.
a scientific discipline that uses nucleic acids or other molecules in different species to infer evolutionary relationships
an approach to systematics in which common descent is the primary criterion used to classify organisms by placing them into groups called clades
Pertaining to a group of taxa that consists of a common ancestor and all its descendants. A monophyletic taxon is equivalent to a clade.
Pertaining to a group of taxa that consists of a common ancestor and some, but not all, of its descendants.
Shared Ancestral Character
A character, shared by members of a particular clade, that originated in an ancestor that is not a member of that clade.
A species or group of species from an evolutionary lineage that is known to have diverged before the lineage that contains the group of species being studied. An outgroup is selected so that its members are closely related to the group of species being studied, but not as closely related as any study-group members are to each other.
A principle that states that when considering multiple explanations for an observation, one should first investigate the simplest explanation that is consistent with the facts.
as applied to systematics, a principle that states that when considering multiple phylogenetic hypotheses, one should take into account the hypothesis that reflects the most likely sequence of evolutionary events, given certain rules about how DNA changes over time
An approach in which features shared by two groups of organisms are predicted (by parsimony) to be present in their common ancestor and all of its descendants.
A method for estimating the time required for a given amount of evolutionary change, based on the observation that some regions of genomes appear to evolve at constant rates.
the hypothesis that much evolutionary change in genes and proteins has no effect on fitness and therefore is not influenced by Darwinian natural selection