Phylogeny

the evolutionary history of a species or taxonomic group; the relationships by ancestry among species or taxonomic groups.

Derived character

a feature that evolved only within a particular taxonomic group.

Species

a group of organisms that are closely related and can mate to produce fertile offspring; also the level of classification below genus and above subspecies.

Taxonomy

the science of describing, naming, and classifying organisms.

Cladistics

a phylogenic classification system that uses shared derived characteristics and ancestry as the sole criterion for grouping taxa.

Binomial nomenclature

a system for giving each organism a two-word scientific name that consists of the genus name followed by the species name.

Species identifier

the second part of an organisms name, the "species" part.

Domain

in a modern taxonomic system, the broadest category; the category that contains kingdoms.

Archaebacteria

in a traditional taxonomic system, a kingdom made of prokaryotes that can live in extreme environments; differentiated from other prokaryotes by various important chemical differences; biologists more recently prefer to classify these organisms as Domain

Eubacteria

in a traditional taxonomic system, a kingdom that contains all prokaryotes except Kingdom Archaebacteria (Domain Archaea); biologists more recently prefer to classify these organisms as Domain Bacteria.

Division

in a traditional taxonomic system for plants, the category contained within a kingdom and containing classes.

Plantae

in a traditional taxonomic system, a kingdom made up of eukaryotic, multicellular organisms that have cell walls made mostly of cellulose, that have pigments that absorb light, and that supply energy and oxygen to themselves and to other life-forms throug

Protist

an organism that is classified as a member of the kingdom Protista; generally, a single-celled or simple multicellular eukaryote that cannot be readily classified as either plant, animal, or fungus.

Biodiversity

the variety of organisms considered at all levels from populations to ecosystems.

Taxon

any particular group within a taxonomic system.

Kingdom

broadest category underneath Domain.

Phyla

Subset below the kingdom.

Classes

subset below phyla.

Orders

subset below class.

Family

subset below order.

Genus

subset below family.

Subspecies

variations of a species that live in different geographic areas.

Phylogenetics

the analysis of the evolutionary or ancestral relationships among taxa.

Phylogenetic diagram

looks like a family tree, and has a branching pattern that indicates how closely related a subset of taxa are thought to be.

Homologous features

items that share a common ancestry.

Analogous features

features that are similar because they have a similar function rather than a similar lineage.

Shared character

a feature that all members of a group have in common.

Clade

group of organisms that includes an ancestor plus all of its descendants.