phylogenetic trees

Uses for Phylo trees

Track spread of diseases, identify species that need to be conserved, and understand evolutionary relationships.

Taxa

Any named group of organisms at any level of classification.

Branch

Represents one species through time on a phylogenetic tree.

Root

The most ancestral branch in a phylogenetic tree.

Tip

The species or taxon at the end of a branch in a phylogenetic tree.

Outgroup

A taxon that diverged before the taxa that are the focus of the study.

Node

The most recent hypothetical common ancestor in a phylogenetic tree.

Polytomy

A branch that splits into 3, indicating insufficient data on relationships.

Ancestral trait

A character that existed in an ancestor.

Derived trait

A modified trait from the ancestor, found in the descendant.

Synapomorphy

A trait in two or more taxa present in their most recent common ancestor but missing in distant ancestors.

Monophyletic group

A group that contains an ancestor and all its descendants.

Homology

Similarity between species due to a common ancestor.

Homoplasy

Similarities between species not due to a common ancestor, often due to convergent evolution.

Parsimony

The principle that the tree requiring the fewest character changes is the most likely.

Evolutionary distance

The average frequency of character state changes between taxa used to find the best-aligning tree.

Convergent Evolution

The development of similar traits in different species due to adaptation to similar environmental conditions.

Adaptive radiation

A single lineage rapidly producing many descendant species with a range of adaptations fitting into different niches.

Niche

The range of conditions that a species can tolerate and the range of resources it can use.

Cambrian Explosion

A rapid diversification of life in the Cambrian period characterized by a significant increase in the variety of life forms.

Mass Extinction

A rapid extinction of a large number of diverse species around the world, often caused by dramatic environmental changes.

Background extinction

The normal low average rates of extinction occurring due to regular environmental changes, disease, predation, and competition.