Picking Mr. Right wastes energy that female iguanas could be using to find food, produce eggs or avoid predators, suggests research published Wednesday.

Princeton University researchers observing Galapagos marine iguanas found that "visiting 'attractive' males carries the highest costs.

Female Galapagos marine iguanas (left) suffer when they are choosy about their mates, suggests research.
(Martin Wikelski)

"The longer female iguanas spend in the company of these appealing suitors the more weight they lose, and the smaller the eggs they subsequently produce," said the news release introducing the research paper, titled High Costs of Female Choice in a Lekking Lizard.

The "attractive" males displayed nearly constant courtship rituals involving walking sideways and bobbing their heads. The females burned energy staying out of their way.

Long periods of sitting up and watching prospective mates also sapped the energy levels of the females.

The resulting weight loss may have dire consequences, the research suggests.
 
"During El Nino years marine iguanas have a hard time finding food, and those that start the season at a low body weight are less likely to live through it."

When El Nino conditions occur, as they do frequently in the Galapagos — islands in the Pacific Ocean, about 965 kilometres west of Ecuador — increased ocean surface temperatures decrease the amount of food algae available to iguanas and many die.

Although females are paying high costs for being choosy, the researchers suspect there may be a positive side.

"Females may choose males with 'better' genes that produce offspring that are more likely to survive," Maren Vitousek told CBC News.

"It's also possible that mating with an attractive male means that you're more likely to produce attractive sons."

As only a small number of males sire most of the offspring, "having sought-after sons could mean that you end up with a lot of grandchildren."

The research paper is available online from the Public Library of Science.