Smell could play a role in origin of new bird species
The study, of organic compounds present in the preen oils of Dark-eyed Juncos, was carried out by researchers at the Indiana University Bloomington, US.
In a new study, scientists have found that two recently diverged populations of a southern California songbird produce unique odors, suggesting smell could contribute to the reproductive isolation that accompanies the origin of new bird species.The study, of organic compounds present in the preen oils of Dark-eyed Juncos, was carried out by researchers at the Indiana University Bloomington, US."There's so much we don't know about the role of smell in bird behavior," said biologist Danielle Whittaker, the study's lead author. "Differences in smell could be affecting sexual behavior, parental care and even contribute to speciation," she said.Led by Whittaker, a team of IU Bloomington biologists and chemists examined the chemical composition of preen oil, which is a compound birds secrete and spread around their bodies to straighten, protect and waterproof their feathers. To analyze the odor chemistry of preen oil, the scientists isolated 19 volatile molecules that can achieve a gaseous, more sniff-friendly state. The scientists found that each junco possesses a unique and recognizable odor profile that was stable over a two-week period and that could be used to distinguish it from other individuals. The odor profiles of male birds differed from those of female birds, and birds' odor profiles differed depending on which population they were from."This is the most comprehensive study of its kind," Whittaker said. "And as far as we know, it is the first time anyone has looked closely at these chemical compounds at the population level in any bird," she said.The team collected juvenile juncos from two populations, one that resides in and around the University of California San Diego campus in La Jolla, California, and another that lives in the Laguna Mountains, about 42 miles east. After capture, the birds were transported to aviaries in Bloomington, Ind., and raised under identical environmental conditions. The scientists used gas chromatography-mass spectrometry to isolate 19 volatile compounds from the preen oils which are secreted from the birds' uropygial glands near the base of the tail.The researchers confirmed that individual birds sampled over time produce levels of each of the volatile compounds that remain more or less constant. They also found gross differences between males and females, and between juncos from the UC San Diego population and birds from the mountains. These population differences were found even though the birds were raised in identical conditions, suggesting that the odors have a genetic, rather than an environmental or developmental basis.