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5 December 2013 11:26 am ,
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An animal rights group known as the Nonhuman Rights Project filed lawsuits in three New York courts this week in an...
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Thousands of scientists in the Russian Academy of Sciences (RAS) are about to lose their jobs as a result of the...
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
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Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
Snake venoms are remarkably complex mixtures that can stun or kill prey within minutes. But more and more researchers...
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
- 5 December 2013 11:26 am , Vol. 342 , #6163
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A Flashy Bill of Health
3 April 2003 (All day)
All across the wild kingdom, males often show off to tell potential mates, “Pick me!” Typically a female bird chooses the one with the brightest body parts or the most melodic song. Now evolutionary biologists have shown that this can be a good move on her part--some displays are true boasts of good health.
Only in the past 20 years have researchers begun to glean how sexual traits can reflect a male's vitality. But until now, they could only speculate about the link between health and showiness. One possible connection is red and yellow pigments called caretenoids, which brighten body parts and strengthen the immune response. Now two research teams have shown that this link does exist in some birds and is reflected in the color of the birds' bills. They report their results in the 4 April issue of Science.
In one study, Jonathan Blount, an evolutionary biologist at the University of Glasgow, U.K., and colleagues fed zebra finches water fortified with carotenoids, while the birds' brothers drank plain water. The added carotenoids made the bird's healthier, their bills redder, and the sex appeal greater--females preferred these birds to their drab siblings. Conversely, a team led by evolutionary biologist Bruno Faivre of the University of Burgundy in Dijon, France, found that blackbirds whose immune systems are under stress have duller bills.
“The studies are important and complementary,” says Joseph Waas of the University of Waikato, New Zealand. Together they provide experimental evidence that bill color is a true indicator of the male's fitness because carotenoids help boost the immune system. As a bonus for females, bill color changes to indicate the male's current vigor. “The characteristics that females really pay attention to are things that reflect the [male's] day-to-day well being,” explains Marlene Zuk, an evolutionary biologist at the University of California, Riverside.