Media

OTTAWA, May 3, 2010  —  In the wake of a global amphibian decline around the world, a team of researchers led by Professor Vance Trudeau from the University of Ottawa’s Department of Biology and colleagues in Argentina, have developed a new method to induce spawning in amphibians.

The decline in frog populations is linked to an increase in diseases, pollution and the loss of breeding habitat. One approach to stop this downturn is the captive breeding of declining or endangered species, but many frogs do not reproduce well in captivity since the environmental conditions in zoos and labs are suboptimal.

Professor Trudeau and his team have found that injection of a combination of brain hormones stimulates successful laying and fertilization of eggs in the common leopard frog, a type of frog that do not breed well in captivity. They invented the amphiplex method, which is a word derived from amphibian amplexus and refers to the specific reproductive behaviour of frogs when the male mounts and clasps the female to stimulate ovulation and to fertilize the eggs as they are laid.

“This new technique offers a new reproductive technology as injection of the hormones overrides the stress of captivity but at the same time stimulates the natural hormones of the pituitary gland.” explains Prof. Trudeau.

Not only can the method be used in Canadian frogs, but the special formulation was also tried in three South American species, as the research was featured in a recent article in the journal Reproductive Biology and Endocrinology.

Among the declining species, the Argentinian horned frog, also known as the Pacman frog, is now endangered as it gains popularity among pet owners. Hormone injections in these animals produced fertile eggs and the researchers were able to study the development of the little known tadpoles.

Studying the Argentinian horned frog led to another unique discovery, published in Acta Zoologica. Dr. Guillermo Natale from the Universidad National La Plata, in collaboration with Prof. Trudeau, discovered that the young tadpoles of the Pacman frogs let out an audible scream when they come under attack. They are the first known larvae of any vertebrate to make sounds. Producing these distress calls is likely to help prevent the tadpoles cannibalizing each other. This finding could have far-reaching implications for our understanding of the behaviours and ecology of amphibians.

“The combination of our reproductive technologies for induced breeding and the expertise of our observant colleagues in Argentina, led to these discoveries that we hope will bring attention to the crisis of disappearing frogs,” concluded Prof. Trudeau.

The University of Ottawa is committed to research excellence and encourages an interdisciplinary approach to knowledge creation, which attracts the best academic talent from across Canada and around the world.