25 February 2009

Biologists Honored on Darwin’s Birthday

Darwin-Wallace medals recognize contributions to evolutionary biology

Duke biologist Mohamed Noor, one of 13 recipients of the 2008 Darwin-Wallace medal.

By Daniel Gorelick
Staff Writer

Washington — In a ceremony commemorating Charles Darwin’s 200th birthday on February 12, 13 scientists received Darwin-Wallace medals for “major advances in evolutionary biology.”

The medals have been awarded every 50 years, beginning in 1908, by the Linnaean Society of London. They commemorate the anniversary of the presentation of the joint paper by Darwin and Alfred Wallace “On the Tendency of Species to form Varieties; and the Perpetuation of Varieties and Species by Natural Means of Selection,” on July 1, 1858.

Darwin and Wallace independently theorized that evolution occurs by natural selection, an idea that has become a bedrock of biology.

“It is truly humbling to be considered alongside such an illustrious group,” said recipient Mohamed Noor, an American geneticist at Duke University, during the ceremony.

The 13 British and American biologists were honored for their work on a variety of evolutionary issues, from understanding how species remain distinct to elaborating on Darwin’s tree of life, increasing understanding of how different species are related to one another.

“This is a very special occasion in the calendar of the Linnean Society of London,” said David Cutler, president of the society, who presented the awards. “Those awarded medals join a group of illustrious names spanning 150 years of research endeavour in this expanding and significant field.”

The Linnaean Society, founded in 1788, is the world’s oldest active biological society. In addition to preserving the specimens and notes of Swedish naturalist Carl Linnaeus, the society promotes the study of evolution, taxonomy, biodiversity and sustainability. The society’s 2,000 fellows from throughout the world range from leading professional scientists to amateur naturalists, according to its Web site.

EVOLUTIONARY ADVANCES

Noor, the son of Egyptian immigrants, spoke on behalf of all the medalists at the ceremony. He highlighted three innovations that have increased scientists’ understanding of evolution since the previous medals were awarded in 1958.

The first innovation is the rise of phylogenetic systematics, the classification of species based on ancestry. “We now know that physical or DNA-sequence similarity does not necessarily demonstrate close relationship,” Noor said. Medal recipient Joseph Felsenstein, a professor at the University of Washington, wrote freely available software that calculates similarities and differences between genes, a crucial component of phylogenetic systematics.

The second innovation is the increase of computational power and availability. “We can now apply approaches that would have seemed absurdly difficult a generation ago,” Noor said, referring to complex mathematical modeling that has generated new predictions about evolution. The “explosion” in computer power “allowed the birth of the disciplines now called bioinformatics and population genomics.”

The third innovation is in genetics. Sequencing DNA has now become routine, allowing many scientists to study the complete genomes of many organisms, “a feat inconceivable 20 years ago,” according to Noor. “While we may not yet know the meaning of all the information we can acquire, we can, essentially, get an organism’s complete genotype to study.”

Noor was honored for his studies on different species of fruit flies, showing how they keep their gene pools distinct by choosing to mate with flies of the same species.

ENDOSYMBIOTIC THEORY

Among the 2008 honorees were Americans Lynn Margulis and the late Stephen Jay Gould.

Margulis popularized and provided evidence in support of the endosymbiotic theory, which argues that parts of animal cells originated from microorganisms such as bacteria. In this theory, primitive cells engulfed bacteria and used them to survive. Over time, the internalized bacteria, or endosymbionts, lost the ability to live independently and became part of the cellular machinery. The cell’s mitochondria, which generate energy and contain their own DNA separate from that found in the cell’s nucleus, are thought to be derived from endosymbiosis.

Gould was recognized posthumously as “the leading spokes-person for evolutionary theory,” according to the award citation. “His monthly columns in Natural History magazine and his popular works on evolution have earned him numerous awards and one of the largest readerships in the popular-science genre.”

He also is known for presenting the theory of punctuated equilibrium, which states that most organisms that reproduce using sex (as opposed to one-celled organisms that simply divide) undergo few changes during their geological history, over millions of years. When evolution does occur, it happens rarely and rapidly.

Other winners include Nick Barton, Mark Chase, Bryan Clarke, Peter Grant, Rosemary Grant, James Mallet, John Maynard-Smith (posthumously), H. Allen Orr and Linda Partridge.

Beginning in 2010, the Linnaean Society will award the Darwin-Wallace medal annually.

For more information on the Darwin-Wallace medals, see the Linnaean Society of London Web site.