Francisco J. Ayala, whose genetic research on the origin of species has revolutionized evolutionary biology, will receive the National Medal of Science, the highest scientific honor in the United States.

Ayala, 68, is one of 15 U.S. scientists and engineers to receive this year's medal. President George W. Bush will honor them at a White House ceremony in late May.

"UC Irvine is extremely proud of Dr. Ayala's accomplishments in his many important roles on behalf of science and science education at UCI, in the nation and around the world," Chancellor Ralph J. Cicerone said.

Ayala is the second UCI faculty member to receive the National Medal of Science. Nobel Prize-winning physicist Frederick D. Reines was awarded the honor in 1983.

"I am extremely humbled and thankful beyond words," Ayala said. "I am particularly pleased that this honor comes to me as a faculty member at UCI, whose achievements and recognitions are growing at an ever accelerated rate, and that so very much has facilitated my work and provided excellent conditions for teaching."

The Donald Bren Professor of Biological Sciences, Ayala has revolutionized evolution theory by pioneering the use of molecular biology methods in the investigation of evolutionary processes. His research has led to a new understanding of the origin of species, the pervasiveness of genetic diversity, the genetic structure of populations and rates of evolution among other concepts.

Ayala's biological discoveries have opened up new approaches to the prevention and treatment of diseases that affect hundreds of millions of individuals worldwide. He demonstrated that the reproduction of Trypanosoma cruzi, the agent of Chagas disease, is mostly the product of cloning, and that only a few clones account for most of this widespread, mostly untreatable South American disease that affects 16 million to 18 million people. This finding opened new approaches for the development of drug therapies and vaccines to combat the disease.

Recently, Ayala reconstructed the evolution of the four Plasmodium species that cause human malaria and discovered that three of them were originally parasitic to non-human species, from which they were transmitted to humans. In further studies on this topic, Ayala and his collaborators also have shown that the worldwide P. falciparum parasites all derive from one single African strain that lived about 5,000 years ago, and that they are genetically uniform, except for the few genes that have recently evolved in response to the human immune system or to drug therapies. Falciparum causes malignant malaria, a disease that debilitates several hundred million people and kills more than 1 million children each year. The public health consequences of this discovery are beginning to be appreciated and are potentially enormous.

"Francisco's research on evolution and genetics has had a significant impact on both the biological and health sciences," said Susan V. Bryant, dean of the School of Biological Sciences at UCI. "In addition, he is a distinguished and articulate spokesman for such issues as science and religion, and the ethics and philosophy of biology. He is a wonderful colleague and has been integral to the continued excellence of biological research at UCI."

Born in Madrid, Spain, Ayala has lived in the United States since 1961 and became a U.S. citizen in 1971. He received his Ph.D. from Columbia University in 1964, and before coming to UCI in 1987, he served on the faculties of UC Davis, Rockefeller University in New York and Providence College in Rhode Island. At UCI, he directs the Bren Fellows Program and holds a joint faculty appointment as a professor of philosophy.

He has published more than 750 articles and is author or editor of 18 books. He is a member of the National Academy of Sciences, the American Academy of Arts and Sciences, the American Philosophical Society, and he has been president and chair of the American Association for the Advancement of Science.

Ayala has received numerous awards for his work, including the Gold Honorary Gregor Mendel Medal from the Czech Academy of Sciences, the Gold Medal of the National Academy of Sciences of Italy, the President's Award of the American Institute of Biological Sciences and the Medal of the College of France.

In addition, Ayala was the founding chair of the Advisory Board of the Dialogue on Science, Ethics, and Religion of the American Association for the Advancement of Science, and he often participates in and speaks about issues concerning society, ethics and religion. He also served as expert witness in the Arkansas trial on the teaching of evolution in December 1981.

Ayala and his wife, Dr. Hana Ayala, live in Irvine. He has two sons, Francisco José, 33, and Carlos Alberto, 30.

The U.S. Congress established the National Medals of Science in 1959 to recognize outstanding lifetime achievement in fields of scientific research. The 2001 awards bring to 401 the total number of science medals awarded since their inception.