January 6, 2010

Even Toads Are Picky About Their Mates

Scientists in Australia have found that the female cane toad will expand her body if she feels a male 'isn't her type.'

According to their study, AFP reports, this suggests frogs and toads may have more power over choosing their mates than we thought. More details on the study appear in the British journal Biology Letters.

The mating process is actually quite interesting. The female toad will choose whichever male gives out the best call.

Sounds simple enough.

However, she must fight off unwanted suitors who will try and climb on her back, grasping her tightly in the armpit or groin, waiting until she starts laying her eggs in order to fertilize them.

By inflating sacs in her body, she is able to loosen her grip and the male slides off her body. Scientists say fertilization among cane toads is most successful when males and females are similar in size.

Cane toads will also puff themselves up in the presence of a predator to make itself look scarier.

Benjamin Phillips and his team went a great distance to test this hypothesis.

They inflated a dead toad with a pump to measure the sacs' air pressure.

Males toads were then given sex hormones to encourage them to mate with the dead females.

After nine living females were given a certain surgery to prevent inflation, it turns out they were unable to shake off even the smallest male. The nine females were killed humanely following the experiments.

"Many of the traits that enable a female to repel a predator also allow her to repel unwanted suitors, and hence facilitate mate choice," the paper notes.

The cane toad, also known as the Giant Neotropical Toad, can weigh up to 5 lbs and can be poisonous to an extent. If ingested, tadpoles can be toxic to animals. Because of its voracious appetite, the cane toad has been introduced to many regions of the Pacific and the Caribbean islands as a method of agricultural pest control.


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