Explosive ice age diversification of kiwi

Area of Science:

• Evolutionary Biology
• Genomics
• Paleoclimatology

Background:

• Global cooling during Pleistocene glacial cycles challenged traditional views on species diversification.
• Some evidence suggests speciation is promoted in habitats near expanding and retracting ice sheets.

Purpose of the Study:

• To investigate a glacially induced burst of diversification in kiwi (avian family).
• To analyze a genome-wide dataset to understand kiwi evolutionary history in relation to glacial cycles.

Main Methods:

• Utilized a genome-wide DNA dataset (>0.5 million base pairs) from kiwi species across their geographic range.
• Employed molecular dating techniques to determine diversification timelines.
• Estimated effective population size through time to identify population bottlenecks.

Main Results:

• Discovered numerous cryptic kiwi lineages, increasing known taxa to 11 (previously 16-17 pre-human arrival).
• Dated 80% of kiwi diversification events to the Middle and Late Pleistocene glacial advances.
• Observed a fivefold increase in diversification rates during key glacial periods, with significant population bottlenecks in most lineages.

Conclusions:

• Kiwi diversification was significantly influenced by Pleistocene glacial cycles and glacial refugia in New Zealand.
• Rapid ice age diversification occurred in kiwi lineages near glaciated regions, supporting the role of climate change in speciation.