Taylor Hallowell ’17 majors in biology. Her thesis examines the sensory drive hypothesis in cichlid fish that express different retinal genes while living under different colors of light. Professor of Biology Ethan Clotfelter is her advisor.
Q: Can you describe your thesis?
A: The sensory drive hypothesis is essentially that there’s a difference in the environment, [which] leads to sensory divergences, like divergences in animals’ sensory systems. That leads to reproductive isolation, and that leads to speciation. There isn’t a ton of evidence for it right now, but there’s an increasing amount. People are starting to take more of an interest in it. I’m trying to get more data for it. I’m working with cichlid fish, which are really common fish to work with because they’re so easy to breed. I have hundreds of little babies already. I’m making them grow up in extreme light environments. A third of them are only getting red light, a third are only getting blue light, and a third are getting just white light. I’m trying to show that differences in light environment cause differences in the expression of the genes in the retina. That would contribute to the sensory drive hypothesis.
Q: Why did you choose that topic?
A: Ethan, my professor, works with cichlid fish. He had gotten some a couple years ago from a lake in Nicaragua and they’ve just been in his lab. He alternates every four years or so between birds and fish, and he just finished up bird stuff this summer, so we’ve just started. He was looking for a thesis student to help him with his fish, and I thought it sounded cool … he told me that I could do any project with the cichlid fish that related to the sensory drive hypothesis.
Q: What were the different phases of your experiment?
A: I actually haven’t collected a whole lot of data yet. I took four females and four males from the fish that [Professor Clotfelter] had, and I put them in four different spawning tanks so there were a male and a female in each tank. It took five days for them to spawn. We had no idea if this was going to work or not, because we needed to figure out a way to get the one-day-old fish from the flower pots [in which they spawn]...up to the tanks one floor up. We ended up just taking the flower pots out and using a turkey baster to suck them all up and squirt them into the new tanks. Ethan said, “You just need to be mentally prepared for the fact that this could kill all of them,” but they’re eight days old now and they’re all alive. For the filters, it turns out that in Belchertown, the town over, there’s a store that sells filters for theaters … [We] just spent a day looking through all of the different wavelength spectra for their filters and picking out the ones we thought would be the best for the most extreme blue, red and white. We went there and we tried to explain what we needed them for, and they thought we were crazy, but they helped us.
Q: Can you expand more on the sensory drive hypothesis?
A: Cichlids have seven opsin genes, which are the genes in their retina, but they only have three turned on at a time. Even though they’re the same species, [cichlids] in Africa living in really clear water have different genes turned on than ones living in really turbid water. My thesis is trying to show that it is the light environment, specifically, that’s causing the different genes to be turned on.
Q: Have you started collecting data yet?
A: I haven’t. I’m taking my first data point when they’re two weeks old, so I’ll do it next week. I’ll get the sequences for their opsin genes, and that will tell me which three they have turned on. Other papers in the past have shown that the three that they have turned on can change throughout their life, so I’m going to test the sequences at a few different times. It takes six months for them to become completely mature, so I will be collecting data right up until the thesis is due. I’m going to do it at two weeks, [and] this two week mark will show me the divergence that I’m looking for.
Q: How long have you spent so far planning or working?
A: I started working on it on August 10. For the first couple weeks, Ethan and I were just sitting down and trying to figure out how all of this could work out, and what exactly we wanted to look for. Then we set up the tanks. Like I said, I paired the spawning pairs in late August and got the fry, the baby fish, a week ago.
Q: What’s been the hardest or the most difficult part so far?
A: I think it’s just handling the time. Since I’m working with live animals, I need to take care of them every day. I have to go even if I don’t have to do other lab work specifically on that day. I at least have to go in and feed them and make sure that the temperature of the tank is okay, that the salinity of the water is correct and that the tanks are clean.
Q: Have there been any particularly fun, funny, or exciting moments?
A: Ethan’s really fun to work with in general because he has a good sense of humor, but I think that the most exciting part was when the babies survived their first night after being moved with a turkey baster. We celebrated the next day.
Q: What are some things that you’re glad you did?
A: I committed to doing this thesis with Ethan last year in the spring semester before I went abroad mostly because I knew that he was a professor that I liked working with. Then I did my study abroad, which was SEA Semester, a marine biology program. I realized that I could really see myself doing marine biology and that I was really happy that I had the opportunity to do this project with fish. I feel like I became more interested in the topic after I decided that I wanted to do it.
Q: Do you think you’ll continue to do research after Amherst?
A: Definitely. I’m not a pre-med student. I’m a biology major because I want to go into research. My field will probably be marine biology, but whatever it is, I want it to be some sort of biodiversity research that could potentially inform management decisions about conservation.
Q: Do you have any advice for potential thesis writers as you look back at your experience so far?
A: Definitely do a thesis. I recommend getting as much done over the summer as you can. Over the summer, when I wasn’t meeting with Ethan and trying to figure out how the experiment itself was going to play out, I was reading all of the background literature to understand what all of the previous research had said. And now, as I go to write my introduction, I’m happy I did all of that reading beforehand and I don’t have to deal with it while I also have to do all the reading for class. Start early, and don’t get behind.
