Genetics of Color Adaptation

What experiments can allow us to find the genes that are responsible for color? What tests show that color actually matters for survival? Professor of Zoology at Harvard University Hopi Hoekstra explains how it is possible to link a DNA base pair change to survival in a natural population.

One of the exciting things about being a biologist now is that we have this incredible opportunity to sequence genomes of organisms. Not only humans, but sort of any organism we want. With all of these data we’re finding variants in these genomes, mutations. At the extremes, there is two types of mutations. And we are interested in those types of mutations for different reasons. So, for example, there are mutations that we consider deleterious or harmful. There are a lot of people who are very interested in identifying these mutations, especially those that affect let’s say human disease.

When we started at the lab one of the first traits we were interested in was color, color adaptation. And this is because it’s a trait that is easy to measure and we already had a hint that color can be important for survival. As mice are running around in their natural habitats they are constantly being barraged by attacks from predators. And one of their primary defenses is simply to blend into their environment.

This sounds like a very simple story, and in part it is, but it’s not just about this one gene. In fact, when we looked at the experiment as a whole there were three regions of the genome that were associated with lighter color. So, I told you a story about the melanocortin 1 receptor, and that in one sense is the simplest story. But there are two other genes that we know to be involved. Another gene is called the agouti signalling protein. Interestingly, it actually physically interacts with melanocortin 1 receptor.