Hunt for Genetic Roots of Evolution Earns Mark Rebeiz Honor of Being Named 2011 Sloan Foundation Fellow

Mark Rebeiz

How did the elephant first get its trunk or the turtle its shell? These are the types of questions University of Pittsburgh biologist Mark Rebeiz hopes to answer with his research. Rebeiz looks for that moment when a gene’s function and expression change to produce “novelties,” characteristics with no genetic precedent, such as the horn of a beetle or the eyespots on a butterfly’s wings.

His pursuit of errant gene activity recently earned Rebeiz, an assistant professor in the Department of Biological Sciences in Pitt’s School of Arts and Sciences, the honor of being named a 2011 Alfred P. Sloan Foundation Fellow, a distinction that carries a two-year, $50,000 grant. In being named a Sloan Fellow, Rebeiz joins 118 young scientists from 54 universities in the United States and Canada, among them Cornell University, Harvard University, the Massachusetts Institute of Technology, the University of California at Berkeley, and the University of Pennsylvania. Rebeiz is the fourth Sloan Fellow from Pitt in the past three years.

Rebeiz works at the forefront of evolution, comparing the genes of an individual with a new trait to the genes of its predecessors. Genes contain regulatory switches that activate gene expression and, ultimately, the characteristics a genetic code will produce. A newly evolved characteristic is often simply the result of an old gene being expressed in a new way, Rebeiz explained. He seeks to understand how and why regulatory switches change to produce novelties.

Many novelties like beetle horns evolved too long ago to detect such slight mutations in regulatory switches. Instead, Rebeiz examines recent developments in fruit flies, for which evolution can be traced in the laboratory. For instance, his lab is beginning to examine the development of the posterior lobe, a microscopic appendage found in only four fruit fly species that a male wields during mating to grasp onto his chosen female. Rebeiz plans to compare the genome of fruit flies sporting this feature to those without it to determine the genetic alterations that gave rise to the lobe. Rebeiz said that his work could be applied beyond the private lives of fruit flies to human genetics as a way to better understand how switches are altered in ways that can lead to disease and deformities.

“When you look molecularly at how an existing biological structure develops, it is incredibly complex, with lots of moving parts,” Rebeiz said. “However, we know that these entities evolved through simple steps. The goal in my lab is to understand those short strides that generate the complex world around us.”

Other Pitt researchers recently named Sloan Fellows include 2010 Fellow Gurudev Dutt, an assistant professor in the Department of Physics and Astronomy; and 2009 Fellows Brent Doiron, an assistant professor in the Department of Mathematics, and Michael Grabe, an assistant professor in the Department of Biological Sciences. Rebeiz is the 33rd Pitt researcher to be selected as a Sloan Fellow since the awards were established in 1955.