Frog Study Receives National Geographic's 7,000th Research Grant

David Braun
National Geographic News
May 9, 2001
A study of frogs that could yield benefits for both conservation and human health has received the 7,000th grant awarded by the National Geographic Society's Committee for Research and Exploration.

The recipient of the grant is Tyrone B. Hayes, 33, an associate professor in the department of integrative biology at the University of California, Berkeley.

Funding for Hayes' research was approved by the National Geographic committee at a recent meeting in Peru, where committee members visited several scientists in the field who are also being supported by the Society.

Hayes' project brings to 7,000 the total number of grants that the Committee for Research and Exploration has awarded since it was established more than a century ago. The long list of grantees and their work includes some of the most distinguished names in research and exploration and a number of milestones in science and discovery (see sidebar).

Hayes will use the grant to further his study of the genus Hyperolius, a reed frog that is common in Africa. His work focuses on frog hormones, many of which are very similar to human hormones.

As part of the research, Hayes will conduct studies of the African reed frog this year in Ethiopia and Uganda. Several members of the Hyperolius genus change color permanently when they reach maturity and are able to reproduce, and in some species the males' coloring is different from that of females. Both traits are rare in frogs, and determining the cause may provide insight as well into characteristics of other species.

"Tyrone is an amazing young scholar [with] extraordinary synthetic abilities," said Raymond B. Huey, professor in the zoology department at the University of Washington. "This is a bold project, which requires a synthesis of very different fields—hormones, embryology and pollution. And he is tackling this not in the lab, but in the bush in Africa."

Probing Color Change

Hayes' research team will observe, count and gather reed frogs in the field to study whether differences in color patterns are genetically controlled and whether hormones alter color patterns.

Exploring the influence of genetics and hormones on color pattern variation in males within a species requires studying different populations of a single species. Hayes' research team wants to determine whether males with different color patterns exhibit different behaviors.

The researchers hope to learn the ecological and evolutionary reasons for the sexual color differences in the species.

"In understanding hormonal mechanisms and potential adaptive advantages within populations, we will gain insight into the mechanisms leading to differences between populations and the differences between species," said Hayes.

Hayes' research has implications for conservation and public health. According to an article in the May 2001 National Geographic magazine, a serious decline in the population of frogs signals something is amiss in the natural world.

Many hormones found in frogs are similar, and in some cases identical, to human hormones. Chemicals that affect hormonal development in frogs could have implications for human health.

Hormones in frogs orchestrate their development from egg to tadpole, and the metamorphosis from tadpole to adult frog. During metamorphosis, frogs are very sensitive to changes in their environment, including chemicals in the water or their food supply.

Possible Bio-Sensor?

Hayes said the extraordinary sensitivity of the frogs' skin means that one day it may be possible to use these amphibians as a cost-effective way to detect the presence of chemicals in water used by humans.

"Many chemicals mimic hormones in their effect on frogs," Hayes said. "We've found that tadpoles show developmental changes in water that has contaminants fifty times lower than what's allowed to be in drinking water in the United States. That's an indication of the ability of frogs to detect pollution in the environment. If chemicals in such low concentrations can impact amphibians, it may be an indication that mammals also may be affected."

"This is exciting research," said Huey. "Tyrone Hayes has discovered that the color of adult frogs is altered by exposure to low levels of toxicants in water.

"But what is so brilliant is Tyrone's realization that this seemingly simple observation can be applied in developing countries as an almost cost-free 'biossay' of pollution," Huey added. "Merely raise some frogs in local water, look at the resultant adults, and one immediately knows whether certain pollutants might be a concern."

More Information

These people were among the latest recipients of grants from National Geographic's Committee for Research and Exploration:

• Cuban-born Lourdes Rodriguez Schettino received a grant for her research on Cuban amphibians and reptiles.
• Croatian anthropologist Ivor Karavanic will conduct paleolithic archaeological research in Dalmatia, Croatia.
• U.K. native Laurence Packer, based in Canada, will continue field work in Chile on bee conservation genetics.
• Astronomer Jay Pasachoff will study the solar corona from Zambia during the June 2001 solar eclipse.
• Anriano Garcia Chiarello, a Brazilian, will assess the success of translocation experiments of sloths in Brazil.
• Polish-born Leszek Karczmarski will conduct behavioral observations of spinner dolphins in the coastal waters of Hawaii.

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