By Susan Milius
Male turkeys often cruise for mates in pairs, but the sidekick seems like the real turkey. He doesn’t get the girl. So, what’s in it for him? A classic answer might be right, recent tests show.
More than 30 years ago, researchers proposed that in an uncertain world, a brother helping his sibling find mates could pass along enough shared genes to compensate for not fathering on his own.
To test that notion, Alan Krakauer of the University of California, Berkeley observed wild turkeys courting alone and in pairs. Their faces and throats flushed bright red and blue as they fanned their tails and wings. In the pairs, however, only the dominant male strutted and made drumming noises. With his buddy’s help, the average dominant male fathered six more chicks than he would have if courting solo.
In genetic analyses, Krakauer confirmed that the pairs were close relatives, probably brothers and half-brothers, with about half of their genes being identical. Thus, the sidekick isn’t wasting his time. Two of his brother’s chicks carry as many of the sidekick’s genes as one of his own chicks would.
Krakauer also knew that males courting alone averaged barely one chick apiece. Therefore, the sidekick passed along more of his genes in the large family produced by a brother teammate than he would have passed by courting alone.
From these results, Krakauer concludes in the March 3 Nature that the reproductive benefit for the sidekick greatly outweighs the cost. Therefore, says the researcher, the decades-old explanation for paired courting in males now has strong data to back it up.
