New Study Shows Colorful Bird Populations Evolve Faster
By Juliana Chan | Featured Research
May 14, 2012
Researchers have found that bird species with multiple plumage color forms within in the same population, evolve into new species faster than those with only one color form.
AsianScientist (May 14, 2012) – Researchers have found that bird species with multiple plumage color forms within in the same population evolve into new species faster than those with only one color form.
In the 1950s, scientists such as Julian Huxley predicted the link between having more than one color variation (color polymorphism) like the iconic red, black, or yellow headed Gouldian finches and the faster evolution of the species.
The global study, which used information from birdwatchers and geneticists accumulated over decades, is the first to confirm Huxley’s 60 year-old major theory in evolutionary biology.
“We found that in three families of birds of prey, the hawks and eagles, the owls and the nightjars, the presence of multiple color forms leads to rapid generation of new species,” said senior author Dr. Devi Stuart-Fox from the University of Melbourne.
“Well known examples of color polymorphic species in these families include the Australian grey goshawk which has a grey and pure white form, the North American eastern screech owl and the Antillean nighthawk, each with grey and red forms.”
The team focused on birds because although color polymorphism occurs in many animals (such as fish, lizards, butterflies and snails), there is a wealth of information on color variation in birds, as well as on species classification (taxonomy), partly thanks to birdwatchers or ‘twitchers’.
“We looked at five bird families with a high proportion of color polymorphism and compared their rates of evolution with those with only one color form,” Stuart-Fox said.
By modeling evolutionary rates using publicly available genetic information accumulated over a quarter of a century, the researchers found that color polymorphism speeds up the generation of new species.
Color polymorphic species tend to evolve into species with only one color form (monomorphic), explaining why existing species with different color forms are relatively young and also rare.
The study found that color polymorphic species were younger not only in the birds of prey but in the songbirds, which account for more than half of the world’s bird species.
“Using many decades of natural history information and 25 years of genetic sequence information we were able to generate the massive family trees, such as a tree of more than four thousand songbirds, needed to model rates of bird evolution in this study,” said lead author Dr. Andrew Hugall.
“Now that we’ve identified this pattern for the first time, our next step is to test some of the explanations proposed for why color polymorphism leads to accelerated evolution.”
The article can be found at: Hugall AF et al. (2012) Accelerated speciation in colour-polymorphic birds.