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|Multiple gene evidence for expansion of extant penguins out of Antarctica due to global cooling|Baker, A.J.; Pereira, S.L.; Haddrath, O.P.; Edge, K.-A. (2006). Multiple gene evidence for expansion of extant penguins out of Antarctica due to global cooling. Proc. - Royal Soc., Biol. Sci. 273(1582): 11-17. hdl.handle.net/10.1098/rspb.2005.3260
In: Proceedings of the Royal Society of London. Series B. The Royal Society: London. ISSN 0962-8452; e-ISSN 1471-2954, meer
|Auteurs|| || Top | Dataset |
- Baker, A.J.
- Pereira, S.L.
- Haddrath, O.P.
- Edge, K.-A.
Classic problems in historical biogeography are where did penguins originate, and why are such mobile birds restricted to the Southern Hemisphere? Competing hypotheses posit they arose in tropical–warm temperate waters, species-diverse cool temperate regions, or in Gondwanaland ~100?mya when it was further north. To test these hypotheses we constructed a strongly supported phylogeny of extant penguins from 5851?bp of mitochondrial and nuclear DNA. Using Bayesian inference of ancestral areas we show that an Antarctic origin of extant taxa is highly likely, and that more derived taxa occur in lower latitudes. Molecular dating estimated penguins originated about 71 million years ago in Gondwanaland when it was further south and cooler. Moreover, extant taxa are inferred to have originated in the Eocene, coincident with the extinction of the larger-bodied fossil taxa as global climate cooled. We hypothesize that, as Antarctica became ice-encrusted, modern penguins expanded via the circumpolar current to oceanic islands within the Antarctic Convergence, and later to the southern continents. Thus, global cooling has had a major impact on penguin evolution, as it has on vertebrates generally. Penguins only reached cooler tropical waters in the Galapagos about 4?mya, and have not crossed the equatorial thermal barrier.