The American wild turkey is a textbook example of cooperative courtship, where subordinate male turkeys help dominant males attract a mate, even though they themselves do not get a chance to breed. When this cooperative courtship was first reported 34 years ago, the behavior was thought to make sense only if the males were related. But that kinship, and thus the entire hypothesis, could not be tested, and, in fact, the details of that study were never published.
"This study not only shows that the males are related, but that the indirect gain in fitness through your relative's gain is equal to or greater than the expense of cooperating," said the study's author, Alan Krakauer. "This is one of the best demonstrations in vertebrates that the benefits of cooperating can outweigh the costs because of kinship alone."
Krakauer, a Ph.D. student in UC Berkeley's Department of Integrative Biology and the Museum of Vertebrate Zoology, published his results in the March 3 issue of Nature.
The cooperative courtship of brother turkeys is one case of the general evolutionary principle of kin selection, which posits that individuals may engage in altruism - behavior detrimental to their survival or reproduction - if the behavior increases the survival or reproductive output of their relatives. Such behavior can include caring for a relative's young or sending out alarm calls to warn nearby relatives at the peril of drawing the attention of a predator.
"Although kin selection is widely invoked as an explanation for cooperation, obtaining the fitness data necessary to demonstrate kin selection can be really tough," said Eileen Lacey, UC Berkeley associate professor of integrative biology and one of Kra
Contact: Robert Sanders
University of California - Berkeley