Phylogeny and Cladistics Review

These flashcards cover key concepts related to phylogeny and cladistics, focusing on their definitions, characteristics, and common mistakes made in constructing cladograms.

Phylogenetic Tree

A diagram representing evolutionary relationships where branch lengths can indicate genetic change or time.

Cladogram

A tree-like diagram showing evolutionary relationships based on shared characteristics, where branch lengths are usually arbitrary.

Clade

A group that includes a common ancestral species and all its descendants.

Derived Characteristics

Traits that are shared among organisms in a clade, represented with hash marks on cladograms.

Sister Taxa

Any taxa derived from a common ancestral node.

Outgroup

A group that diverged before the ingroups being studied in cladistics.

Common Ancestor

The most recent ancestor shared by two or more groups.

The snip rule states that if you snip before a node, all sister taxa fall off.

Mistake in Cladogram Construction: Phantom Taxon

The bottom line should not extend past the last organism on the cladogram.

Mistake in Cladogram Construction: Ladder-like Continuation

All organisms on a cladogram should be level to represent equal evolutionary continuation.