Understanding Phylogenetic Trees and Evolutionary Relationships

Phylogenetic Tree

A diagram showing evolutionary relationships among organisms.

Root

Represents the ancestral lineage in a phylogenetic tree.

Branch Tips

Most recent descendants of an ancestral lineage.

Evolutionary Lineage

Sequence of ancestral organisms leading to a descendant.

Branch Point

Node indicating a common ancestor and speciation.

Common Ancestor

Ancestral organism giving rise to multiple lineages.

Most Recent Common Ancestor (MRCA)

Youngest ancestor from which all lineages descend.

Sister Taxa

Groups sharing a common ancestor not shared with others.

Systematics

Discipline classifying organisms and their evolutionary relationships.

Morphological Data

Physical characteristics used to infer evolutionary relationships.

Molecular Data

Genetic information used to determine phylogenetic relationships.

Shared Ancestral Character

Character originating in an ancestor of the taxon.

Derived Character

Evolutionary novelty unique to a specific clade.

Homology

Similarity due to shared ancestry among organisms.

Analogy

Similarity due to convergent evolution, not ancestry.

Outgroup

Species closely related to, but not part of the ingroup.

Ingroup

Group of species being studied in phylogenetic analysis.

Branch Length

Represents time or genetic divergence in phylogenetic trees.

Maximum Parsimony

Method assuming the simplest tree requires fewest changes.

Convergent Evolution

Unrelated species evolve similar traits due to environment.

Clade

Group including an ancestor and all its descendants.

Speciation

Process where one lineage splits into two or more.

Unique Characters

Features that are specific to a particular lineage.

Shared Characters

Features resulting from common ancestry among organisms.

Divergence

Process where lineages evolve different traits over time.

Phylogenetic Analysis

Study of evolutionary relationships using trees and data.