Chapter 20 2/3

Phylogeny

The evolutionary history of a species or group of species.

Systematics

The discipline that classifies organisms and determines evolutionary relationships.

Taxonomy

The order, division, and naming of organisms; a way to classify organisms based on similarities and evolutionary relationships.

Binomial nomenclature

A two-part naming system for species, including the genus and species name.

Genus

The first part of the binomial nomenclature, representing a group of closely related species.

Species

The second part of the binomial nomenclature, representing the specific organism within the genus.

Taxon

A taxonomic unit at any level of hierarchy.

Sister taxa

Groups of organisms that share an immediate common ancestor.

Basal taxon

A lineage that diverged early from the common ancestor of a group.

Polytomy

A branch point in a phylogenetic tree where more than two groups emerge.

Phylogenetic tree

A branching diagram that represents the evolutionary relationships among species.

Common ancestor

An ancestral species from which two or more descendant taxa have diverged.

Eukaryotic

Organisms that have a nucleus and membrane-bound organelles.

Chordates

Animals that possess a notochord at some stage of development.

Carnivora

An order of mammals that primarily have a carnivorous diet.

Hierarchical classification

A system of organizing living things into groups based on shared characteristics, from broad to narrow.

Characteristics of taxonomy

Classification of organisms based on resemblances and genetic makeup, which has changed over time.

Cladogram

A diagram that shows the relationships among organisms based on shared traits.