Tuesday, April 18, 2006
When William Duellman stumbled across a small, odd frog in the jungles of Panama in 1963, it was the start of a long career.
While studying tree frogs, Duellman, a retired ecology and systematics professor and curator of Herpetology at the University of Kansas, discovered a frog with a pouch on its back. Now, 42 years and 22 marsupial frog species later, he is still adding to his life’s list.
“I am not ‘one of,’ I am the leading expert on marsupial frogs,” Duellman said.
Duellman continues to do research on marsupial frogs because he said he is trying to understand the biodiversity of the planet. The greatest diversity of life is in the tropics where his frogs live, he said.
In 2003, Duellman discovered the most recent frog species in northern Peru with the help of Pablo Venegas, a member of the faculty at Facultad de Medicina Veterinaria de la Universidad Nacional Pedro Ruiz Gallo in Peru. Their findings were recently published by the Herpetologists’ League in its quarterly journal, Herpetologica.
The newest species of marsupial frogs are different from other marsupial frogs because of a flat, spatula-shaped skull and different-colored skin that is fused to the skull, Duellman said. Most marsupial frogs have big robust skulls, Duellman said. The newest species he found brought the number Duellman has discovered to 22. Only 46 species of marsupial amphibians are known at this time.
Currently, Duellman is working on a diary of DNA analyses to better understand the marsupial frogs. He needs tissue samples that have not been preserved, so he must go back into the field and look for more live specimens, Duellman said.
Since 1963 The National Science Foundation has funded all of his research on the marsupial frogs. Duellman has traveled many times to places like Panama, Columbia and other Central and South American countries to look for frogs in places where people haven’t been before, he said.
“I have been chasing the damn things for 43 years,” he said. “Sometimes you are successful, but just as many times you are not.”
The marsupial is a rarity in the frog world, said Juan Manuel Guayasamin, Quito, Ecuador, graduate student in the division of evolutionary biology at the University of Kansas.
“Marsupial frogs are one of the extreme products of evolution,” he said. “Through time, female marsupial frogs have evolved a pouch on the back where fertilized eggs are placed.”
Marsupial frogs generally live in the area from Costa Rica to Argentina. Most of the species live in the Andes Mountains. These frogs can range from a couple of centimeters long to almost four inches and they eat mostly insects, Duellman said.
According to Duellman, there is nothing special about the structure of the pouch. It is a pocket in the middle of the back that is used as an incubation system for fertilized eggs. The females carry these eggs in the pouch until they hatch and leave “momma and go off on their own,” Duellman said.
This evolutionary rarity has helped the marsupial frog become partially or completely independent of water, said Guayasamin. By being independent of water the marsupial frog can live high in trees.
“It is possible that generations and generations can go by without any of these frogs ever touching the ground,” Duellman said. “These are the ones that are hard to find, as you can imagine.”
The marsupial frog is thought to have evolved from another species of tree frog, Duellman said. This type of tree frog lived mainly in North and South America. Over time, a brood pouch developed and the marsupial frog was born, Duellman said.
Even though Duellman, 76, retired from teaching systematics and ecology in December 1996, he still enjoys being able to use the University’s facilities for his work.
“What is better than getting paid for what you like to do?” Duellman said. Then he thought about his statement again and added: “At least I used to get paid.”
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