科学美国人60秒 SSS 2014-07-30（在线收听） |
When you think of birds, you probably imagine their dazzling plumage or their beautiful songs. But since the days of Darwin, scientists have figured that individual species of birds should not have both: they’d either be drab virtuosos or eye candy that sings only one note. Now a study shows that some songbirds are in fact show-offs in sight and sound. The work is in the Proceedings of the Royal Society B. [Nicholas A. Mason, Allison J. Shultz and Kevin J. Burns, Elaborate visual and acoustic signals evolve independently in a large, phenotypically diverse radiation of songbirds] Bright feathers and complex songs are different ways to attract a mate. The more flamboyant the display, the more likely a bird will get noticed. But these exaggerated calling cards take a lot of energy to produce. Which is why scientists assumed that birds would have to choose between melody or looks.
But an exhaustive survey of the tanagers, a family of songbirds from Central and South America, shows no sign of a tradeoff. Although some tanager species do emphasize oration over attire, like the aptly named drab hemispingus, some, like the mountain tanager, are both dashing and melodious. While the white-bellied seedeater is fine with looking and sounding rather dull.
The different species likely experienced different selective pressures, leading to their varied strategies. Whatever it takes to catch the eye, and/or ear, of a potential mate. |
| 原文地址：http://www.tingroom.com/lesson/sasss/2014/7/271201.html |