Research in Molecular Design Could Have Implications for Evolutionary Genetics

Alpan Raval's paper, “Molecular Clock on a Neutral Network,” has been accepted by the prestigious physics journal, Physical Review Letters.

Claremont, CA, September 01, 2007 --( Claremont Graduate University Assistant Professor of Mathematics Alpan Raval has written a paper, “Molecular Clock on a Neutral Network,” that has been accepted by the prestigious physics journal, Physical Review Letters.

Raval’s paper lends insight into the disparity between terrestrial species, and is a step towards helping clarify the discrepancies in the molecular clock technique for estimating the time of emergence of new species. There are currently two ways to attempt to find the time when a new species first emerged in evolution: DNA/protein analysis or carbon dating of fossils. However, these methods often do not agree, as the accumulation of mutations in DNA or protein sequences often exhibits large variability. Such sequences are called “erratic molecular clocks”.

Raval’s research, which involves mathematics and biology, focuses on identifying the conditions under which protein sequences could be good or erratic molecular clocks. An implication of his work is that proteins which can function robustly when virtually any site in them is mutated, but quickly become non-functional when these mutations are simultaneous, will be good molecular clocks. This leaves much of the guesswork behind in terms of identifying good molecular clocks for studying speciation in evolution. With this information handy, evolutionary geneticists can expect to map the history of all species with more precision, focusing on the types of proteins that have stood the test of time.

“Estimating dates for the emergence of new species over the course of evolution is a pressing problem, and a common method used to address it is the so-called ‘molecular clock’ technique,” Raval said. “The best molecular clocks will be proteins that can withstand mutations at many different sites, but not withstand simultaneous mutations at these sites, making them traceable over millions of years of evolutionary history.”

“The idea of a molecular clock is extremely important in genetics, potentially allowing researchers to determine the date when two species diverged,” said John Angus, Dean of the School of Mathematical Sciences. “Alpan’s paper sheds light on the nature of the statistical error that can occur in such dating schemes. This can have a great impact on estimates of when various species arose."

Chris Adami, Professor of Applied Life Sciences at Keck Graduate Institute in Claremont, agreed that Raval’s work is groundbreaking.

“Nobody has yet pinpointed the ideal clock protein, but Alpan's formula now can tell us where to look,” Adami said.

Raval has been part of Claremont’s School of Mathematical Sciences since 2002. He is a joint professor at Keck Graduate Institute.

Claremont Graduate University
Nikolaos Johnson