Summary
Rapid diversification of a lineage into many forms filling different niches, as with Hawaiian honeycreepers.
In depth
After a colonist enters an environment with empty niches or after a mass extinction, a lineage diversifies. Examples: Darwin's finches (about 15 species), Hawaiian honeycreepers, African cichlids and mammals after the dinosaur extinction.
It is rapid on geological timescales.
Triggers include a new environment (islands, lakes), a key innovation (such as pharyngeal jaws in cichlids or flowers in plants) and the end of competitors by extinction. Hawaiian silverswords diversified from a single tarweed ancestor into around 30 species ranging from trees to ground mats. Lake Malawi has an estimated 500 to 1000 cichlid species.
After the extinction of dinosaurs, mammals radiated into bats, whales, primates and others within about 10 million years. The pattern is recognised by many species from a common ancestor occupying varied niches, each with different adaptations. Lizards of Caribbean Anolis radiated into ecomorphs on each island independently.
Frequently asked questions
What is Adaptive Radiation?
Rapid diversification of a lineage into many forms filling different niches, as with Hawaiian honeycreepers.
Which area of biology covers Adaptive Radiation, and how advanced is it?
Adaptive Radiation is one of the 53 topics in Evolution. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Allopatric Speciation, Phylogenetic Trees, Divergent Evolution.
Why does Adaptive Radiation matter?
Radiations show how ecological opportunity and evolutionary innovation generate biodiversity.
Can you give an example of Adaptive Radiation?
Marsupials in Australia filled niches equivalent to placental mammals elsewhere.
What should I learn before Adaptive Radiation?
Work through the Beginner topics in Evolution first, such as Evolution, Natural Selection, Charles Darwin, then return to Adaptive Radiation. Intermediate topics assume the Beginner vocabulary.
What topics are related to Adaptive Radiation?
The closest topics to Adaptive Radiation are Allopatric Speciation, Phylogenetic Trees, Divergent Evolution, Extinction. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Adaptive Radiation?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Adaptive Radiation. To practise the whole of Evolution, use the Evolution quiz.
How is Adaptive Radiation different from Allopatric Speciation?
Adaptive Radiation: Rapid diversification of a lineage into many forms filling different niches, as with Hawaiian honeycreepers. Allopatric Speciation: Speciation after a geographic barrier separates populations, as with Darwin's finches on separate islands. Read both side by side and note what each one explains.
How should I study Adaptive Radiation step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Allopatric Speciation and explain the difference aloud. Finally, take the Evolution quiz and come back to this page for any question you miss.