Hey Lady Lizards: Get a Whiff of This!
 If a guy wants to smell nice for his lady, a splash of aftershave or cologne usually does the trick. Male lizards take a slightly different approach. They eat vitamins.
When it comes to choosing a mate, female animals scope out the healthiest and most fertile males. Sometimes appearance matters most; the colorful tail of a male peacock, for example, attracts predators - so surviving males are judged fit enough to escape their enemies. A male's odor may also tag him as a good catch, but scientist’s aren't as clear on how this works.
Evolutionary ecologists José Martín and Pilar López of the National Museum of Natural Sciences in Madrid, Spain, wondered if rock lizards could provide an answer. Male Iberian rock lizards (Lacerta monticola) mark their territory with a secretion from their leg glands that contains provitamin D (a precursor to vitamin D). Like humans, lizards need vitamin D for strong bones. Healthy males on a good diet have an abundance of vitamin D and can therefore afford to secrete some of it as provitamin D. Can female lizards pick up on this lavish "spending?"
To find out, the team fed 20 male lizards a strict diet of mealworms, supplementing half with a liquid side-dish of vitamin D. After 2 days on the diet, the males on the supplement had 1.6 times more provitamin D in their gland secretions than controls. Lizards, like snakes, detect airborne odors by flicking their tongues-appealing odors get more flicks.
Females preferred swabs taken from the glands of vitamin supplemented males over controls, gracing them with twice as many tongue flicks. Females also directed 1.5 times more tongue flicks at swabs soaked in pure provitamin D than at swabs soaked in related chemicals from the gland secretions, such as cholesterol, the team reports online 19 July in Proceedings of the Royal Society of London B.
It's quite likely that females are using provitamin D levels as a measure of male fitness, says Martín. However, further experiments will be needed to determine whether males with more provitamin D in their secretions actually get the girl more often, he notes.
"This is a neat study, nicely carried out," says behavioral scientist Tristram Wyatt of the University of Oxford in the United Kingdom. The researchers have chosen a good system for investigating this kind of problem as they can easily manipulate one of the key nutrients involved, he adds.
Source: Science Magazine
|
