The female's aphrodisiac song, called "rapping," is a rapid series of loud clicks that sound like a Geiger counter exposed to a lode of uranium. It is among the rare instances in the animal kingdom where the female takes the first step.

Conventional wisdom in biology is that males advertise for mates and females answer: peacocks display, peahens admire; cocks crow, hens attend. It is extremely uncommon for females to initiate courtship, and "advertisement songs" that indicate receptivity had been thought to be the exclusive province of males. The male South African clawed frog, Xenopus laevis, had been thought to advertise his availability first, with a distinctive trill, and then to grab in succession the nearest females, releasing those that were not ready to lay eggs.

The new work, reported in the Feb. 17 issue of the Proceedings of the National Academy of Sciences, contradicts this view. The research, which also sheds light on how hormones may affect the nervous system, was conducted by Darcy B. Kelley, professor of biological sciences; Martha L. Tobias, senior research scientist, and Sandya S. Viswanathan, a graduate student in neurobiology and behavior, all at Columbia.

A female frog faces an urgent problem: there is a span of only about 24 hours in which her eggs are ready to receive sperm. She must attract a suitor during that period, or lose her progeny. Mating takes place at night in murky ponds crammed with frogs, making it difficult for receptive females to locate males, even though the males vocalize continuously during breedi
'"/>

Contact: Bob Nelson, Office of Public Affairs
rjn2@columbia.edu
(212) 854-6580
Columbia University
17-Feb-1998