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Colour variation speeds up evolution

In a recent study into colour polymorphism in birds, we found that the presence of multiple colour forms leads to the rapid generation of new species. While the link between multiple colour morphs and the evolution of new species was proposed by Sir Julian Huxley in the 1950s, ours was the first study to confirm it. Research into this area is important because it improves our understanding about the processes that generate biodiversity, and provides insight into to why some groups of species diversify rapidly while others stay the same for millions of years.

Using an extensive data set of genetic data from ‘GenBank’ collected over a quarter of a century, we generated large ‘trees’ (phylogenies) allowing us to compare rates of speciation associated with colour polymorphism. Our data contained genetic information from five families of birds with a high occurrence of colour polymorphism, and included more than 4100 species in total.

We found that in three families – hawks and eagles, owls, and nightjars – the presence of multiple colour forms leads to the rapid generation of new species. We found that those polymorphic species that do speciate commonly evolve into species with only one colour form – i.e. the polymorphism is lost. The next step is to examine why species with multiple colour forms evolve faster, by looking for general patterns among polymorphic species or at specific processes in individual species. One of our current research projects examines colour polymorphism and speciation in the tawny dragon lizard.

To learn more, read the full paper:

Hugall, A.F. and Stuart-Fox, D. 2012. Accelerated speciation in colour-polymorphic birds. Nature 485: 631–634 (31 May 2012). PDF

Or view media coverage of the study:

Colour variation speeds up evolution – Science Illustrated (17 May 2012)
Colourful birds evolve faster – Science Alert (14 May 2012)
Species with multiple colours evolve faster – The Conversation (10 May 2012)
Bird color variations speed up evolution – Science Daily (9 May 2012)

Photo credit: Larry Hitchens

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