Chapter 1: Evolution, Diversity, and Classification of Vertebrates

Amniotes

Vertebrates with the derived character of three fetal membranes: amnion, chorion, and allantois

Sauropsids

The lineage of amniotes represented by extant non-avian reptiles and birds and their extinct relatives (reptiles)

Synapsida

The lineage of amniotes represented by extant mammals and their extinct relatives (mammals)

Systematics

The evolutionary classification of organisms

Binomial Nomenclature

The linnean system of identifying a species with a generic and specific name

Taxa

A group of organisms of any rank

Taxonomy

The discipline that assigns names to organisms

Phylogenetic Systematics

The grouping of taxa according to the evolutionary relationships

Derived Characters / Apomorphy

A character that has changed from its ancestral state

Shared Derived Characters / Synapomorphies

A derived character shared by two or more taxa and postulated to have been inherited from their common ancestor

Plesiomorphies

A character that is unchanged from its ancestral condition

Symplesiomorphy

An ancestral character that is shared by two or more taxa

Phylogenies

Evolutionary relationships based on the branching sequence of lineages

Outgroup

A reference group that is less closely related to the group under study than the members of ingroup are related to each other

Ingroup

The evolutionary group under study

Molecular Scaffolding

Using molecular data to determine the branching pattern of phylogenies and morphological data to date the branching

Basal Taxon

The lineage closest to the ancestral form

Extant Phylogenetic Bracket

Using character states of two extant lineages to infer the character states of extinct taxa that lie between extant taxa in a phylogeny

Paraphyletic

An evolutionary lineage that does not include an ancestor and all of its descendants

Sister Group

The monophyletic lineage that is most closely related to the monophyletic lineage being discussed

Monophyletic

An evolutionary lineage that includes an ancestor and all of its descendants

Crown Groups

Members of a crown group have all the derived characters of a lineage

Stem Group

Extinct forms in a lineage that lack some of the derived characters that define the crown group

Modern Synthesis

The blending of genetics, natural selection, and population biology that occurred in the 1930s and 1940s

Darwinian Fitness

The genetic contribution of an individual to succeeding generations relative to the contributions of other members of its population

Heterochrony

Changes in the timing of gene expression during development

Heterotopy

A change in the location of a genes expression during development

Paedomorphosis

Retention of larval or embryonic characters into adult life

Heterometry

A change in the intensity of a genes expression during development

Epigenetic

Modification of gene expression during development by non-genetic factors, such as temperature