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Since male peacocks appear to shiver in response to female run-arounds, the scientists think that male mating calls, which consist of multiple notes and sound very different than the noises females make, could affect mating success. The trains, on the other hand, may just be obsolete signals at this point, they suggest. Louise Barrett, a member of the Faculty of Science and Technology at the University of Central Lancashire in Preston, U.K., thinks the reason for their obsolescence could be that, unlike many other elaborate traits in birds and animals, peacock trains are dictated by the female hormone estrogen, rather than testosterone. Barrett said that "it is the absence of estrogen in the male that produces the train, rather than the presence of testosterone." "Traits under the control of estrogen are usually very poor indicators of phenotypic (visible physical attributes) and genotypic (DNA) condition," she explained. "Accordingly, females are known to disregard estrogen-dependent male plumage cues when choosing mates." Barrett, however, mentioned that this theory, along with the rest of the new findings, is bound to be controversial, since other researchers have presented data suggesting that a peacock's train does influence whether or not a female will choose to mate with him. "Tests between the two alternate hypotheses now on offer leave students of sexual selection with plenty of work to do," Barrett concluded. Related Links: Jennifer Viegas' blog: Born Animal San Diego Zoo's Animal Bytes: Peafowl |
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