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News Release 05-192

When Froggy Goes a Courtin'

Females don't fall for the same old song when distant groups reconnect

Speciation of green-eyed tree frog

Populations of frogs differed in subtle ways following a geographic change that isolated them.


November 1, 2005

This material is available primarily for archival purposes. Telephone numbers or other contact information may be out of date; please see current contact information at media contacts.

Distance can be hard on relationships--especially if you are a 2.5- inch frog. So, after a million years, when geographically isolated green-eyed tree frogs (Litoria genimaculata) reconnected with their former group, the females exercised a newfound mate selectivity based on a unique male mating call. This ensured the finicky females paired only with males from their new group and generated a distinct frog species in just 8,000 years or so.

"That's lightning-fast," for species development, said University of California, Berkeley researcher Craig Moritz.

Moritz and Australian colleague Conrad Hoskin studied the impact of geographic changes that began several million years ago and caused a single population of green-eyed tree frogs in Australia's rainforest to split into distinct northern and southern groups. About 8,000 years ago, another environmental change allowed the two groups to intermingle. By then, frogs produced from a northern male-southern female pairing didn't survive well. As a result, a crossbreeding southern female was at a reproductive disadvantage.

The selection pressure led to a mating strategy in which southern female frogs preferentially selected southern males by virtue of his distinctive call. The behavior of the females therefore sped up, or reinforced, the normal speciation process. In a few thousand years a new species that could no longer mate successfully with either the northern or southern frogs developed.

This type of reinforcement of natural selection has been controversial since Darwin's time, but Moritz and Hoskin provided data to support the concept in the Oct. 27 issue of Nature.

The U.S. National Science Foundation and the Australian Cooperative Research Centre for Tropical Rainforest Ecology and Management sponsored this research.

For the complete story, see the University of California, Berkeley news release.

-NSF-

Media Contacts
Richard (Randy) Vines, NSF, (703) 292-7963, email: rvines@nsf.gov

Principal Investigators
Craig Moritz, University of California, Berkeley, (510) 643-7711, email: craigm@berkeley.edu

The U.S. National Science Foundation propels the nation forward by advancing fundamental research in all fields of science and engineering. NSF supports research and people by providing facilities, instruments and funding to support their ingenuity and sustain the U.S. as a global leader in research and innovation. With a fiscal year 2023 budget of $9.5 billion, NSF funds reach all 50 states through grants to nearly 2,000 colleges, universities and institutions. Each year, NSF receives more than 40,000 competitive proposals and makes about 11,000 new awards. Those awards include support for cooperative research with industry, Arctic and Antarctic research and operations, and U.S. participation in international scientific efforts.

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