(3) Unit 7 Topic 9 Packet

Phylogeny

The study of the evolutionary history and relationships among individuals or groups of organisms.

Systematics

The classification of organisms and the determination of their evolutionary relationships.

Taxonomy

The naming and classifying of species.

Phylogenetics

A hypothesis of evolutionary history represented through diagrams such as phylogenetic trees.

Phylogenetic tree

A diagram that represents the evolutionary history of a group of organisms, showing the amount of change over time.

Cladogram

A simplified diagram showing evolutionary relationships among organisms based on shared characteristics.

Node

A branching point in a cladogram that represents a common ancestor.

Clade

A group of organisms that includes an ancestor and all its descendants.

Root

The common ancestor of all species represented in a cladogram.

Sister taxa

Two clades that emerge from the same node on a cladogram.

Basal taxon

A lineage that evolved from the root and remains unbranched.

Synapomorphies

Derived characteristics that are shared by all members of a clade.

Derived characteristic

A similarity inherited from the most recent common ancestor of a group.

Ancestral characteristic

A similarity that arose prior to the common ancestor.

Outgroup

A lineage that is the least closely related to the rest of the organisms in a study.

Monophyletic group

Involves the most recent common ancestor of a group and all its descendants.

Paraphyletic group

Includes the most recent common ancestor of a group but not all its descendants.

Polyphyletic group

Does not include the most recent common ancestor of all the members.

Parsimony

A principle that suggests using the hypothesis that requires the fewest assumptions, helpful in constructing cladograms.