Ronald Mumme’s students inspired by research

Students learn life lessons doing senior comprehensive project

Tyler Stigall, Staff Writer

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Dr. Ronald Mumme, professor of biology at Allegheny College, describes himself as a behavioral ecologist and field biologist.

“My job is to learn new things about the natural world,” he explained. “The more people know about the natural world and the cool things organisms do in their environments, it creates a greater appreciation of nature, which is not a bad thing to produce.”

His main area of interest and expertise is in the behavior of the hooded warbler, but most of his senior students research different but similar animal models for their comprehensive projects.

“The warbler is a migratory songbird that’s here from around the first of May to about the fifteenth of September,” Mumme said. “Generally, comp students work on other animal behavioral projects.”

It is no surprise then that two of his students, Thomas Richter, ’15, and Rebecca Skwarko, ’15, decided to examine guppies.

Most behavioral experiments involve several different disciplines in biology, according to Mumme. An experiment can examine a physiological mechanism and analyze it within a much broader ecological context.

This may explain why both Skwarko and Richter drafted their ideas while taking a junior seminar that dealt with the evolution of shape and morphology and later turned to Mumme, an ecologist, as their comprehensive project advisor.

Mumme’s advisees are indeed examining a range of behavioral, physiological and neurological phenomena.

“One student is interested in looking at the effects of music on memory tasks in mice,” Mumme said. “Another is looking at the effects of maternal immune challenge on behavior in the offspring. Two other students are interested in mouse neurodegenerative disorders—one in Alzheimer’s, one in Huntington’s.”

Both Skwarko and Richter studied sexual selection—the selection of mates based on behavioral or physical traits—in guppies for their comprehensive projects.

Skwarko examined a species of guppies in which the females prefer males with a more saturated orange coloration. Richter examined the selection of gonopodium size—which is essentially the size of the fish’s genitals, according to Richter—in red fire guppies.

Skwarko said, “I had a fish tank divided on two sides by one-way glass, with a female in the middle and males on either end. It was set up so that the female could see the males, but the males could not see the females, because then they would exhibit sexual behavior, which would be a confounding variable.”

Skwarko’s experiment involved two parts: one in which a female was placed with two live males, and a second part, in which two computer monitors were shown on either end of the tank. On a Powerpoint slide, a picture of a male guppy was shown to move about the screen. On one monitor, the guppy’s color saturation had been digitally increased; on the other, the picture’s saturation was diminished.

Of her results, Skwarko said, “The females preferred the live males overall, but the results for the videos were comparable. The females significantly preferred the more color-saturated males over dull-colored males in both the video and live experiments.”

Skwarko rotated through fifteen females and thirty males in forty trials total for the live trials of her experiment. The computer animation involved the same picture of a single male, shown again to all fifteen females.

Richter’s experimental setup was similar. He got the idea after reading a paper that measured sexual selection for gonopodium size in a different species of fish and he sought to confirm those findings in red fire guppies.

“If females prefer large gonopodium, why do we not see runaway selection?” Richter said. “Why do we not see every fish with large gonopodium?”

Richter also performed a two-part experiment: the first involved proving that females prefer males with larger gonopodia and the second tested whether males with smaller gonopodia could swim faster, when startled, than those with larger gonopodia.

For the former experiment, Richter also used a Powerpoint presentation with a pair of doctored images of a single male guppy, one with an enlarged gonopodium, the other with a shrunken one. Females were shown one video for ten minutes, given five minutes to acclimate, and shown the second video for another ten minutes. The time that each female spent in a designated area close to the monitor was then measured.

During the second experiment, Richter essentially startled his guppies and measured, with a high-speed camera above the tank, the time in which each fish swam erratically before bolting off in a straight line.

“For mate choice, I found that the females significantly preferred the larger gonopodium,” Richter said. “For swimming speed, there was a weak positive correlation between gonopodium size and swim speed and I attribute that to my small sample size.”

Richter explained that while he only used nine males for the second part of his experiment, the study on which he based his model off of used forty individuals. This particular study found statistically significant results. Richter speculated that he might have obtained different data if he had included a larger sample size.

Both Richter and Skwarko consider their experiments successes. The key, according to Richter, is to do a lot of research beforehand in order to justify a hypothesis and any potentially significant findings.

“You need patience,” Richter said. “Especially if you’re working with animals, because they don’t always cooperate.”

“Things definitely go wrong,” Skwarko said. “And as you go, you figure things out.”

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