Figuring out how a genome evolves
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| Stephen Proulx |
It takes about 30,000 genes to make a human being, only five times the number of genes in yeast.
And, explained Stephen Proulx, the differences in number are due mostly to changes in the size of existing gene families, groups of genes that evolved from a common ancestral gene. Proulx joined the faculty of the ecology, evolution and organismal biology department last summer and gene families are one subject of his research. The institute assisted in recruiting him to Iowa State.
As a theoretical biologist, Proulx uses mathematical tools and computer models to determine how environmental and evolutionary factors such as seasonal change, migration and sexual preference structure a genome. His models explore how genomes become diverse and evolve.
One path to diversity in a genome involves the proliferation of genes into multi-gene families. The growth of a gene family can occur through rare errors in DNA replication. Sometimes in error, a single gene is duplicated on a chromosome, and the duplicated copy can emerge as a new functional gene. While that gene may have a new function, it's not fundamentally different from the original gene.
Proulx's model calculates the exact conditions under which evolutionary pressures cause genes to diverge.
“One of the things I'm trying to do is provide an ecological and environmental context and what I continue to see is that these ecological factors can play a really large role,” said Proulx.
The gene family model is one of several projects Proulx is working on. Other areas of interest include mating system evolution, the evolution host-pathogen systems, and the evolution of robustness in genetic networks.
