Read phylogenetic trees and connect common ancestry, evidence, extinction, and diversification.
Part of the free Knowledge Mountain biology library. Read an explanation, try a question, and use a memory cue to check what you can recall.
A phylogenetic tree is a hypothesis about evolutionary relationships. A branch point represents a common ancestor. Taxa sharing a more recent common ancestor are more closely related.
Rotating branches around a node does not change their relationships. A tip higher on the page is not more evolved than a tip below it.
Two branches swap left-to-right positions around the same node on a phylogenetic tree. Have the evolutionary relationships changed?
No.
Branch order on the page can change without altering the branching pattern. Relationships depend on common ancestry, not visual closeness between the tips.
Homologous structures share ancestry, even if their functions differ. Analogous features have similar functions that evolved independently. Convergent evolution can produce analogous similarities.
A human arm and a whale flipper share an inherited skeletal pattern. Streamlined bodies can evolve independently in distantly related swimmers.
How can a major extinction be followed by adaptive radiation in surviving lineages?
Survivors may diversify as they exploit newly available habitats and resources.
Adaptive radiation is the evolution of many forms from a shared ancestral lineage, often associated with ecological opportunity. It is not a guarantee that every survivor diversifies.