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How traits evolve

How traits evolve

Dave Larsen January 05, 2023
Associate professor of biology, Tom Williams
Associate professor of biology, Tom Williams


In an organism that has around 13,000 genes, only 100 or 200 are responsible for making a physical characteristic.

"How is it that these genes know in which cells and when during life to be active?" asked associate professor of biology Tom Williams, who studies how physical traits develop and evolve at the DNA level.

To find out, he’s using a National Science Foundation grant of more than $1 million awarded this fall to grow his research lab staff to one doctoral, two master’s and eight undergraduate students. Together, they will find and characterize the parts of genes in fruit flies responsible for variations in abdomen color patterns.

"Everything we’re asking here about fruit flies are the same things that have to be spelled out in the language of our own DNA to make sure things are produced in the right place at the right times during development," Williams said. "When changes happen in the DNA sequence and it goes wrong, we get things like genetic diseases or a variation from one individual to another."

In the last decade, the NSF has awarded Williams more than $2.3 million in grants for his evolutionary developmental research.

  • Previously, Williams studied ways in which DNA sequences function to switch genes "on" and "off" during an organism’s development.

  • He then studied how evolution used these so-called "genetic switches" to develop biological diversity.

  • "Heart attack risk or cholesterol variations in families — a lot of times this is under the control of the switches." - Williams

  • Roughly 60% of the fruit fly’s genes can be found in humans in similar form, and about 75% of the genes responsible for human diseases have counterparts in flies.

  • Because the fruit fly can birth a generation in only 10 to 15 days, Williams can follow evolutional changes through as many as 24 generations per year.

  • "The lessons we learn about the genes in fruit flies give us insights about how these genes might be functioning in our bodies as well." - Williams

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