Biology Chapter 20 Phylogenies

What is a taxon?

Any names group of organisms at any level

What is a phylogeny?

Evolutionary history of a group of organisms

What is a root?

The oldest common ancestor in the tree

What is a node?

Branching point representing a common ancestor

What is a tip?

Species or taxon at the end of a branch

What is a sister taxa/sister clades?

Lineages that share a most recent common ancestor

What is a clade?

A group that includes an ancestor and all descendants

What is a monophyletic group?

Includes an ancestor and all of its descendants (a clade)

What is a paraphyletic group?

Contains common ancestors and some descendants

What is a polyphyletic group?

Group that does not include any common ancestors (only tips)

What is plesiomorphy?

The ancestral trait for a particular clade

What is apomorphy?

A derived or changed trait for a particular clade

What is a synapomorphy?

A derived trait that is shared by members of a clade, used to identify clades and reveal patterns of shared evolutionary history

What is a homologous trait?

Traits that have shared similar evolutionary origins

What is an analogous trait?

Traits that evolved independently for the same function via convergent evolution

What is evolutionary reversals?

Occurs when a lineage reverts to an ancestral traits

What is homoplasy?

Similar traits that evolved independently through convergent evolution or by an evolutionary reversal

What is convergent evolution?

When different species independently evolve similar traits, even though they are not closely related.

What is the parsimony principle?

The best phylogenetic tree requires the fewest evolutionary changes

What is a molecular clock?

Method that uses the rate of genetic change to estimate evolutionary time