Bird song goes out of fashion too

Just as the Bee Gees' disco style sounds antique compared to hip-hop, birdsong can also go out of fashion. Such stylistic changes may help explain how mating barriers arise, eventually leading to new species.

Behavioural ecologists have long known that some songbirds develop local dialects, and that individual birds respond more strongly to their own dialect than to a foreign one. Less is known about how, or how quickly, such differences arise.

To study how a dialect changes over time, Elizabeth Derryberry, a behavioural ecologist at Duke University in Durham, North Carolina, compared recordings of male white-crowned sparrows' song from 1979 - when the Bee Gees topped the charts - and 2003. The modern song, she found, was slower and lower in pitch.

This difference mattered to the birds. When Derryberry played the songs to 10 female and 20 male birds, she found that females solicit more copulations and males showed more aggressive territorial behaviour to the contemporary song than to the older ones - even though the recordings were of equal quality and no bird had ever met any of the recorded individuals (Evolution, DOI: 10.1111/j.1558-5646.2007.00154.x). The result shows that meaningful differences in song styles can arise within just a few years, and thus that mating barriers can be erected quickly, says Derryberry.

From issue 2611 of New Scientist magazine, 05 July 2007, page 17

05 July 2007 NewScientist.com news service http://www.newscientist.com/article.ns?id=mg19526115.000

[评论]

这对语言的进化研究有着直接的作用，随着语言的分化，不同人群的婚育就产生了障碍，人们就越倾向于在同一语言群体内部来进行交配和生育，于是也就对人类种群的分化产生了影响。其实到现在，人类也大多数还是在同一语言群体内部进行婚育，尽管跨语言群体的婚姻比例有所增加了。