How Aussie lizards avoid sex
Australian researchers have revealed an unusual method of female species of a lizard who roll on their back showing their bright orange underside in a bid to avoid sex with their male counterparts.
Devi Stuart-Fox of Melbourne University along with his team has reported their findings that will be published in Journal of Comparative Physiology A. In most animals, that use colourful displays for attraction, it's usually the male that's flashy, such as the peacock. But female Lake Eyre dragon lizard (Ctenophorus maculosus) is an exception, the findings reveal, according to ABC report.
It states 'she (lizard) displays a bright orange belly and throat during parts of her breeding season, which researchers think is driven by the hormone testosterone. The colour features prominently when the female wants to put off a male from copulating with her. Stuart-Fox took a close look at a number of female lizards taken from Lake Eyre in South Australia and observed what happened when they were in the company of males.
When Lake Eyre lizards copulate the male bites the female's neck, climbs on top of her, wraps his tail around hers and inserts one of his two penises. This can be hazardous to the health of the female because when the males bite them on the neck this can pierce the female's spine and result in death.
Therefore, once the female's eggs have been fertilised, she will try to avoid mating. But males aren't easily put off. "The males are really persistent," Stuart-Fox said and added "They try and force copulation and they harass females all through the breeding season."
Unreceptive females scare off advancing males by taking on a threatening posture. If this doesn't work, they throw themselves on their backs and reveal their bright orange underside. "Males can't actually force themselves onto a female when she's on her back," Stuart-Fox said who measured the levels of sex steroids in blood samples taken from the lizards over time.
Progesterone and testosterone usually decrease once female lizards are no longer receptive to mating, but not in the Lake Eyre dragon lizard. "They maintain high testosterone levels all through the reproductive cycle including when they weren't receptive later in the cycle," he said. The researchers believe the testosterone is used to drive the female courtship rejection behaviours.
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