Featured Research

from universities, journals, and other organizations

Colonizing songbirds lost sense of syntax

Date:
September 26, 2013
Source:
Duke University
Summary:
As one species of European songbird island-hopped to colonize mid-Atlantic archipelagoes over the course of a half million years, their songs lost their sense of syntax.

Songs of the European chaffinch lose their syntactical structure the further out the birds are found on the mid-Atlantic archipelago.
Credit: Robert Lachlan, Duke University

As one species of European songbird island-hopped to colonize mid-Atlantic archipelagoes over the course of a half million years, their songs lost their sense of syntax.

Chaffinches (Fringilla coelebs) on the furthest island of their dispersal, Gran Canaria in the Canary Islands, still sing the same notes, but with a much less structured pattern from one bird to the next, sort of like an island of Charlie Parkers.

"A chaffinch from mainland Europe always sounds like a chaffinch from mainland Europe," said biologist Robert F. Lachlan who completed the 15-year study of chaffinch song structure during a post-doctoral fellowship at Duke University. But on Gran Canaria, it's much harder for a human to pick them out by hearing alone, he said.

Lachlan recorded the songs of 723 males in 12 different populations across the European mainland, the Azores and the Canary Islands and compared them computationally. Subunits of the songs, which he calls syllables, differed slightly between populations, but the sequencing of the syllables -- the syntax -- was progressively less predictable the further the birds got out on the chain of colonization.

The work appears Oct. 7 in the journal Current Biology. It was funded by the Dutch Science Foundation and Duke University.

Syntactical structure was lost in a step-wise fashion that matches the known dispersal of the species across these islands. At the end of the island chain, "the syntax isn't just changing, it's disappearing," Lachlan said. "It's not about changing the rules, it's about losing them."

Lachlan says one factor in the loss may have been that island birds face fewer competing species. Whereas a female chaffinch might be trying to pick out the right male among 60 other songbird species singing all at once in Europe; in the Azores, she faces just eight other songbirds. The males are the singers. "One of the jobs the female has is to identify her own species."

Unfortunately the data don't completely match that idea, Lachlan said. There are almost twice as many species on the Canary Islands as on the Azores, yet the Canary Island songs have much less structure. "Other factors must also be involved," Lachlan said.

A large body of research has shown that birds learn their species-specific song from their elders. If cultural transmission were the only source of syntactical structure in the songs, however, one would expect songs from the smaller island populations to have more structure than those from the mainland not less, Lachlan said.

But there is also a genetic component to that learning. Hundreds of genes have been identified which relate to song learning and singing. Studies show that young birds have a genetic predisposition that helps them pick out which songs they ought to be learning in order to develop species-typical songs.

"It seems very likely that what we measured is the result of the evolution of such genes," Lachlan said.

One of two plausible explanations for the loss of syntactical structure may be something called a "cultural trap," Lachlan said. "In small populations, like those on islands shortly after colonization, an evolutionary interaction between culture and genetic predisposition favors individuals that can recognize and learn a wider range of songs -- in this case, a wider range of syntactical patterns."

It may also be a case of "withdrawal of learning," he said. When populations are very small on the new island, young birds may find few tutors to learn from. Some of the young birds would be forced to improvise, and this would introduce new songs into the population at a higher rate than normal, leading to rapid change in song structure.

Now that he has established this pattern of syntactical loss across the islands, Lachlan hopes to use it to investigate the causes of song learning evolution.


Story Source:

The above story is based on materials provided by Duke University. Note: Materials may be edited for content and length.


Journal Reference:

  1. RobertF. Lachlan, MachteldN. Verzijden, CarolineS. Bernard, Peter-Paul Jonker, Bram Koese, Shirley Jaarsma, Willemijn Spoor, PeterJ.B. Slater, Carel tenCate. The Progressive Loss of Syntactical Structure in Bird Song along an Island Colonization Chain. Current Biology, 2013; DOI: 10.1016/j.cub.2013.07.057

Cite This Page:

Duke University. "Colonizing songbirds lost sense of syntax." ScienceDaily. ScienceDaily, 26 September 2013. <www.sciencedaily.com/releases/2013/09/130926123453.htm>.
Duke University. (2013, September 26). Colonizing songbirds lost sense of syntax. ScienceDaily. Retrieved August 23, 2014 from www.sciencedaily.com/releases/2013/09/130926123453.htm
Duke University. "Colonizing songbirds lost sense of syntax." ScienceDaily. www.sciencedaily.com/releases/2013/09/130926123453.htm (accessed August 23, 2014).

Share This




More Plants & Animals News

Saturday, August 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Endangered Red Wolves Face Uncertain Future

Endangered Red Wolves Face Uncertain Future

AP (Aug. 22, 2014) A federal judge temporarily banned coyote hunting to save endangered red wolves, but local hunters say that the wolf preservation program does more harm than good. Meanwhile federal officials are reviewing its wolf program in North Carolina. (Aug. 22) Video provided by AP
Powered by NewsLook.com
Farm Resurgence Grows With Younger Crowd

Farm Resurgence Grows With Younger Crowd

AP (Aug. 22, 2014) New England farms are seeing a surge in younger farm hands as the 'buy local' food movement grows across the country. (Aug. 22) Video provided by AP
Powered by NewsLook.com
Drug Used To Treat 'Ebola's Cousin' Shows Promise

Drug Used To Treat 'Ebola's Cousin' Shows Promise

Newsy (Aug. 21, 2014) An experimental drug used to treat Marburg virus in rhesus monkeys could give new insight into a similar treatment for Ebola. Video provided by Newsy
Powered by NewsLook.com
Terrifying City-Dwelling Spiders Are Bigger And More Fertile

Terrifying City-Dwelling Spiders Are Bigger And More Fertile

Newsy (Aug. 21, 2014) According to a new study, spiders that live in cities are bigger, fatter and multiply faster. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins