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Ice sheets promote speciation in boreal birds
1Department of Zoology, University of British Columbia, Vancouver, V6T 1Z4, Canada. weir@zoology.ubc.ca
Proceedings. Biological Sciences
|September 7, 2004
Summary
Pleistocene ice ages significantly drove speciation in boreal bird species by fragmenting habitats. This contrasts with lower-latitude species, suggesting ice sheet impacts accelerated avian diversification.
Area of Science:
- Evolutionary Biology
- Quaternary Science
- Ornithology
Background:
- Previous studies suggested ice ages had limited impact on species diversity, citing pre-Pleistocene coalescence times.
- Research was biased towards low-latitude species, not directly affected by glacial fragmentation.
Purpose of the Study:
- To investigate the role of Pleistocene ice ages in avian speciation at high latitudes.
- To compare speciation timing in boreal, sub-boreal, and tropical avifaunas.
Main Methods:
- Mitochondrial sequence divergence analysis.
- Molecular clock dating of avian superspecies complexes.
- Comparison of coalescence times across latitudinal gradients.
Main Results:
- All studied boreal avian superspecies coalesced during the Pleistocene.
- Boreal species divergence correlates with ice sheet fragmentation of boreal forests.
- Lower percentages of sub-boreal (56%) and tropical (46%) species coalesced during the Pleistocene.
Conclusions:
- Pleistocene ice sheets were a major driver of speciation in high-latitude boreal avifaunas.
- Habitat fragmentation by glaciers accelerated diversification rates in boreal species.
- Boreal refugia may have imposed strong selection, promoting rapid ecological differentiation.