BIO Chapter 26: Phylogeny and the Tree of Life (up to 26.4)

Phylogeny

The evolutionary history of a group or species of related species.

Systematics

A discipline focused on classifying organisms and determining their evolutionary relationships.

Binomial

A two-part scientific name made of genus and species for species hierarchical classification.

Taxon

The categories used in taxonomy that nest within each other.

Branch point (in a phylogenetic tree)

Represents the divergence of two evolutionary lineages from a common ancestor.

Sister taxa

Groups that share a common ancestor that is not shared by any other group.

Basal taxon

Fishes are considered the basal taxon because they diverged from all other members of the group early in history.

Clade

A group of species that contains their ancestors and all of its descendants.

Monophyletic

A group that contains its ancestor and all descendants.

Paraphyletic

A group that contains ancestors and some descendants.

Polyphyletic

A group that contains commonly related species but not their most recent ancestor.

Shared derived characters

Traits that are evolutionary novelties unique to a particular clade, used in the development of clades.

Shared ancestral character

A character that originated in an ancestor of the taxon.

Orthologous genes

Genes that can only diverge after speciation has taken place.

Paralogous genes

Genes that result from gene duplication and have diverged from one another within a species.

Gene duplication

The process that leads to the distinction between orthologous and paralogous genes.

Homologous structures

Structures that inform about different aspects of an organism’s history and lineage.

Analogous structures

Structures similar due to convergent evolution, not common ancestry.

Sequence alignment

A method used to determine DNA homologies despite genetic changes.

Hair (as a shared derived character)

A specific character of mammals, reflecting evolutionary novelty for the group.

Backbone (as a shared ancestral character)

A characteristic shared with other vertebrate groups, indicating common ancestry.

Hypothesis (in relation to phylogenetic trees)

The concept that phylogenetic trees represent a hypothesis about how organisms are related.

Mice (as model organisms)

Mice are often excellent model organisms for studying human diseases due to genetic similarities.