Frog girlfriend can't hear you? Just wave!
The Local · 3 May 2016, 20:53
Published: 03 May 2016 20:53 GMT+02:00
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The study into instinctive behaviour has been held as ground-breaking by showing how hormones can also trigger automatic behaviour, not only in making the frogs wave, but in limiting their ability to croak.
The endangered green-spotted rock frog (Staurois tuberilinguis) lives in areas around waterfalls, making it hard to win territory, and therefore mate, with croaking because of the noise of the water which drowns out its calls.
Instead the frogs have developed a habit of waving in order to signal their presence, and now scientists have discovered that it is the male sex hormone that stimulates the frog to wave.
The discovery was made by an international cooperation between scientists in Austria and the United States that involved studying frogs being kept in Vienna's Schönbrunn Zoo, the oldest zoo in the world.
The tiny frogs, which are just an inch in length and come from Borneo, have evolved with 10 times more receptors to androgenic hormones - a testoid that controls sexual development in males - in their hind legs than other types of frog.
And the presence of the hormone is what makes the male frogs wave to signal they are in the area, according to the team led by Doris Preininger from Schönbrunn Zoo as well as physiologist Lisa Mangiamele, from Smith College and Matt Fuxjager, from Wake Forest University, both in the USA.
Speaking to Central European News, Johanna Bukovsky said: "Our research shows how hormones are used in a sex-selective way to control muscle movement - namely the visual communication by feet."
"The evolutionary advantage is that the frog that waves has more chance of showing his presence and defending his territory, and less risk of having to fight to do so. That means he has a place to attract females."
It means that evolution favoured more receptors in the legs for the male hormone, she added.
Zoo Director Dagmar Schratter said: "It is often unclear how animal gestures have evolved into a repertoire of signals. Our results show that frogs developed waiving by evolutionary changes in hormone sensitivity in their muscles."
Story courtesy of Central European News