The Oasi Naturale Lamastrone in Garfagnana was the location today for the first Toads Sex Olympics of spring 2018.
music by The Aristodemo’s
Sex in many toads, frogs and other amphibians involves a male mounting a female’s back and gripping her by the armpits. This amorous embrace, called amplexus, places the animals’ cloacas – an all-purpose orifice at the rear that excretes feces, urine, eggs and sperm – close together.
Fertilization is best assured when the toady couple is similar in size and their cloacas line up. In most toads, females are the larger sex, so they benefit from shacking up with the bigger males.
Mating season competition, however, is intense. Male toads gather around suitable waterholes, croak out to attract mates and jump on any female when she approaches. The males then battle each other for the best or – ideally for one of them – the sole amplexus position – staying in amplexus for several days.
The outcome of this struggle is that the strongest male will win the right to fertilise the female’s eggs and pass on his genes to the next generation. While the female lays eggs, the male on her back spreads sperm over them. Toad spawn is laid in a long double helix chain of around 7,000 eggs and is wrapped around the vegetation in the water.
Female toads inflate to avoid sex
When it comes to choosing a mate, female toads may have more control than previously thought, say scientists.
A report in the Royal Society’s Biology Letters journal describes how a female toad inflates its body to prevent an amorous male from mating with it. This makes it difficult for the male toad to “hold on”.
Male toads often wrestle with each other in an effort to grasp a mate but, according to Dr Benjamin Phillips from the University of Sydney, bodily inflation could be “a widespread mechanism of mate choice” in frogs and toads.
Dr Phillips and his team explained in their research paper that male toads will “grasp any female that comes within reach and retain their hold unless displaced by a rival male”.
In their experiments, the scientists found that male toads were less able to maintain this grip if the female inflated its body.
Scientists had noticed previously that females inflated their bodies during male-male wrestling matches.
They assumed that this inflation was just a response to the physical stress of being pushed, prodded and occasionally knocked over by males but females can actually manipulate the outcome of male-male competition by inflating at the right moment.
This could help ensure that the female gets to mate the the biggest, strongest male, which is likely to produce the healthiest offspring.
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