Frogs: Female choice for complex calls led to evolution of unusual male vocal cord

May 03, 2006

Male tropical túngara frogs have evolved masses on their vocal cords that help them woo females with complex calls, show scientists working at the Smithsonian Tropical Research Institute (STRI) in Panama.

Dr. Mike Ryan, Clark Hubbs Regents Professor of integrative biology at The University of Texas at Austin, Dr. Marcos Gridi-Papp, a post-doctoral scholar in physiological sciences at UCLA, and the late Dr. Stan Rand, of STRI, published their findings in the May 4 issue of Nature.

Males of the túngara frog, Physalaemus pustulosus, attract females by singing out "whine chuck chuck" calls in wetlands and puddles during the rainy season. The males may only produce whines, but females are more attracted to males that also produce chucks.

The scientists surgically removed the fibrous masses in the males' larynx and found that they could no longer produce the "chuck". The frogs produced a normal whine and attempted to add chucks to it, but the sounds that they added lacked the distinctive pattern of the chuck.

"By removing the structure within the larynx, we eliminated the ability of a frog to produce a complex call," says Ryan. "Now we know that there is a structure associated with a single syllable of the call."

"The experiment shows that the fibrous masses produce the complexity in the calls of male túngara frogs," adds Gridi-Papp, who was a post-doctoral researcher at Universidade Estadual Paulista in Brazil during this study.

Taken together with the fact that female preference for complex male calls most likely evolved before males could actually produce them, Gridi-Papp says this shows that the fibrous masses on the male vocal cords evolved in response to female preference.

"Besides shaping the behavior of males, female preferences also indirectly shape the anatomy of the calling apparatus of males by favoring enlarged fibrous masses that allow for production of complex calls," says Gridi-Papp.

"The simple connection between the fibrous mass and call complexity gives us a unique opportunity to dissect the evolution of acoustic complexity," Gridi-Papp says.

Comparative studies looking at the fibrous masses of other species in the same genus may reveal why complex calling evolved in the túngara frog lineage and not in others.

Such studies will help explain the origins of complex traits, one of the major evolutionary questions for biologists since Charles Darwin.

Source: Smithsonian Tropical Research Institute

Explore further: Himalayan Viagra fuels caterpillar fungus gold rush

add to favorites email to friend print save as pdf

Related Stories

A high price to pay for cheap technology

Sep 17, 2013

Rape in war cannot be addressed in isolation. It is deeply embedded in both the local context and that of global proportions. This is one of the conclusions made in a doctoral thesis about eastern Democratic Republic of Congo ...

Recommended for you

Literature searches benefit from location tagging

7 minutes ago

Agricultural Research Service ecologist Jason Karl is creating new options for helping researchers to conduct literature searches that go beyond using traditional search terms such as keywords or authors. ...

Himalayan Viagra fuels caterpillar fungus gold rush

14 hours ago

Overwhelmed by speculators trying to cash-in on a prized medicinal fungus known as Himalayan Viagra, two isolated Tibetan communities have managed to do at the local level what world leaders often fail to ...

Science casts light on sex in the orchard

16 hours ago

Persimmons are among the small club of plants with separate sexes—individual trees are either male or female. Now scientists at the University of California, Davis, and Kyoto University in Japan have discovered ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.