Why are some individuals more attractive to the opposite sex than others? New research by a team from University College London and Oxford University, published in PLOS Genetics, has shown that in wild turkeys (Meleagris gallopavo), the essence of male beauty is mainly dependent on the way that males use their genes, rather than differences in the genes themselves.
Males and females in many animals show profound differences in how they look and act, and some of these differences are key to sexual attractiveness. Within each sex, individuals often show a range of these sex differences, with both males and females being more or less masculine or feminine. This variation in sex differences is puzzling, as it seems evolutionarily logical that every individual would want to be as attractive as possible to the opposite sex, in order to maximise their chances of producing offspring.
Male wild turkeys come in two morphs: dominant males show an exaggeration of male traits, such as: head colouration and snood length, which attract females, while subordinate males are less ornate. Subordinate and dominant brothers work together during the breeding season to attract females, but subordinate males never actually mate and father offspring themselves. Instead, they are the perfect and perennial wingmen, helping to pull in females for their dominant brother to mate with and potentially furthering their own genes indirectly through their sibling.
Dominant and subordinate males showed profound and wide-spread differences in the way they express the majority of genes in their genome. Dominant males were both masculinized (showed higher expression of genes predominantly found in males) and defeminized (showed lower expression for genes predominantly found in females). Thus, attractiveness in male turkeys is more a function of how they use their genes, rather than differences in the genes themselves.