Each circle represents a Hawaiian island, with geological ages noted; molecular dating shows that endemic Drosophila species on each island are youngest on the youngest islands.
Hawaiian Drosophila species on each island are most closely related to species on the next-older island. This pattern reflects
- A
Convergent evolution from soil bacteria
- Bcheck_circle
Progression rule via colonization of new islands and adaptive radiation
- C
Independent origin on each island from the mainland
- D
Hybridization across the entire archipelago
Explanation
The progression rule describes a stepping-stone colonization pattern in island chains: new species form by colonizing newly emerged islands and radiating, mirroring the geological age progression.