Chapter 14: Evolutionary relationships

Common ancestor

A species or organism whose offspring diverged over time

Homology

A similarity due to a common origin

Molecular homology

The identification of shared biomolecular elements – generally genes – used to test the relationships between organisms, which can demonstrate common ancestry

Comparative genomics

The study of DNA similarities across species

Conserved sequence

A DNA or protein sequence that is preserved across species because it is necessary for optimal function

Residue

A single unit that makes up a polymer; e.g. a single amino acid in a protein sequence

Mutation rate

The estimated number of base pair changes per nucleotide site per generation of a population

Phylogenetic tree

A branching diagram showing evolutionary relationships

Cladistics

A taxonomic technique that arranges organisms by clade

Clade

A group consisting of all the descendants of a particular ancestor organism

Cladogram

A phylogenetic tree in which all organisms are grouped according to their most likely evolutionary relationships

Phylogram

A phylogenetic tree in which branch length or width represents genetic differences or time since divergence

Dichotomous

Having two branches, two opposing aspects

Extant

Currently in existence, not extinct

Node

A point in a diagram where lines branch or intersect

Phylogenetic relationship

An evolutionary relationship that exists between a group of species, often expressed as a tree-like diagram

Character matrix

A table of characteristics used for classification