Over on the Eurekalert page, there is this press release: In túngara frogs, female choice for complex calls led to evolution of unusual male vocal cord. The male frogs have fibrous masses on the vocal cords. Researchers surgically removed the masses in some males, who thereafter could not produce the “chuck” part of the typical mating call in this species of “whine chuck chuck”. The female frog preference for males able to make the more complex call provides a basis for selection leading to the trait of having fibrous masses on the vocal cords.
This research complements Basolo’s earlier study finding that platyfish females in species without “swords” preferred males with artificial swords (Basolo, A.L. 1990. Female preference predates the evolution of the sword in swordtail fish. Science, 250:808-810.).