AsianScientist (Nov. 9, 2016) – Tropical birds such as parrots and parakeets are well known for their colorful appearance, and the popularity of these birds leads many to assume that tropical climates are home to a greater proportion of colorful birds than temperate climates. But how exactly does a geographical region influence the evolution of a species?
Dr. Nicholas Friedman from the Okinawa Institute of Science and Technology Graduate University in Japan and Dr. Vladimír Remeš from Palacký University in the Czech Republic examined a total of 137 different species from two major songbird families in Australia. The familial relationships of the birds that they examined were compared using an evolutionary tree based on the birds’ DNA. They then used a special instrument to measure the color of the feathers in particular places on the birds, and data from satellites to describe the geographical region each species lives in.
Contrary to what you might think, the researchers found that bird species in the tropics do not evolve more colorful feathers compared to their cousins in temperate climates. The work was published in Global Ecology and Biogeography.
“If you look at birds in the tropics, there are a lot of colorful birds that stand out. But there are really more species in general there, and there are just as many more of the little brown ones,” described Friedman. “Instead, birds living in the harsh arid climates of inland Australia tended to have fancier colors than those in the lush tropical islands. Since desert birds have to scramble for mates during the wet season, we think they may be evolving colors that can attract mates quickly.”
Meanwhile, birds thriving in climates with more precipitation and vegetation are darker in color overall, while desert birds tend to be lighter. Birds living in the desert tend to be more grey on their backs, while birds living in the forest have evolved to be more of a dark green. According to Friedman, this would be an example of natural selection; in this case, more camouflaged organisms can survive and pass on their genes.
The article can be found at: Friedman and Remes (2016) Ecogeographical Gradients in Plumage Coloration among Australasian Songbird Clades.
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Source: Okinawa Institute of Science and Technology Graduate University; Photo: Pexels.
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