BIO 103: Ch. 26 Systematics, Phylogenies, and Comparative Biology Vocab

Systematics

A scientific discipline focused on the reconstruction and study of evolutionary relationships among living things.

Taxonomy

The science of classifying living things (= the hierarchical grouping of organisms). By agreement among taxonomists, no two organisms can have the same name, and all names are expressed in Latin.

Taxon

A named taxonomic unit at any given level of classification; plural is taxa.

Phylogeny

The evolutionary history of an organism (may include taxa within a species and/or species that are closely and distantly related); describe what order related species evolved and this "order" is often represented in the form of an evolutionary tree.

Phylogenetic Tree

A branching diagram that represents a hypothesis about the evolutionary history of a group of organisms. Modern DNA sequencing techniques have produced phylogenetic trees showing the evolutionary history of individual genes.

Evolutionary Lineage

The sequence of ancestral organisms leading to a particular taxon; represented by a branch (line) in a phylogenetic tree.

Branch Point

The representation on a phylogenetic tree of the divergence of two or more taxa from a common ancestor; also called a node. A branch point is usually shown as a dichotomy in which a branch representing the ancestral lineage splits (at the branch point) into two branches, one for each of the descendant lineages.

Sister Taxa

Groups of organisms that share an immediate common ancestor and hence are each other's closest relatives.

Convergent Evolution

The evolution of similar features in independent evolutionary lineages; in other words, the process by which unrelated organisms independently evolve similarities (e.g. when adapting to similar function, to similar environments, etc.... example: wings in birds and bats).

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. Example, a backbone if examining mammals.

Shared Derived Character

An evolutionary novelty that is unique to a particular clade. In other words, character states (e.g. hair, mammary glands) that is shared by species (e.g. mammals) and that are different from the ancestral state.

Clade

A group of species that includes an ancestral species and all its descendants. A clade is equivalent to a monophyletic group.

Molecular Clock

A method for estimating the time required for a given amount of evolutionary change, based on the observation that some regions of genomes evolve at constant rates.