Biology Professor Studies Unusual Mating Behavior
Standing in ankle-deep water under the fiery South Texas sun, Dr. Caitlin Gabor grips one end of a net the size of a bedsheet and hurls it into the stream. Moments later she drags it ashore and begins to rummage through its contents for mollies, fish no bigger than her finger.
Gabor, an associate professor in the Department of Biology at Texas State University-San Marcos, received a $300,000 grant from the National Science Foundation to study the mating behavior of the Amazon molly, an unusual, all-female species.
Named for the mythical, all-female warriors, Amazon mollies are live-bearing fish that reside in the brackish waters along the South Texas coast. These genetically identical clones must mate with males of other species to stimulate egg development. Those males, however, contribute no genetic material to the offspring.
Evolution Mystery “Students in my lab are studying questions related to how Amazon mollies have persisted for almost 100,000 years,” Gabor says. The studies involve the mating behavior of Amazon mollies and sailfin mollies, which are closely related to Amazon mollies but have both males and females within the species.
After collecting the two species, Gabor brings them to her laboratory on campus where she and her students conduct various studies and observe the fish in action.
Male sailfin mollies that coexist with Amazon mollies would be expected to avoid mating with the all-female Amazons, because evolution programs individuals to pass along their own genes. Yet the male sailfin mollies have mated with the Amazons for thousands of years. Gabor wants to know why.
“We found that male sailfin mollies make more mating mistakes when the Amazon mollies are larger than female sailfin mollies,” Gabor says. “This is because larger females have more eggs and therefore are usually higher quality mates, unless males are being ‘tricked’ by these sexual parasites.”
Gabor and her students also collect sperm from the sailfin mollies to gauge their reaction to females of their own species versus their reaction to Amazon mollies.
“We found that while male sailfin mollies produce more sperm in the presence of sailfin molly females, they actually expend more sperm when mating with Amazon mollies,” she says. “This was contrary to our prediction.
“However,” she continues, “our graduate student at the time realized that it may be that males were rapidly making sperm while mating with sailfin mollies but not when mating with Amazon mollies. These results suggest that male sailfin mollies are sperm-limited and make more sperm only when they are mating with their own species.”
The results from Gabor’s first study on sperm production have been highlighted by the Canadian Broadcasting Corp. radio show “Quirks and Quarks” and in numerous magazines.
Gabor’s Evolution Gabor, who came to Texas State seven years ago, uses both behavioral and genetic-based experiments and says she enjoys “letting the organisms tell you why they do things” through her experiments. She teaches organismal biology, behavioral ecology and evolutionary ecology.
Caitlin Gabor became interested in biology as a 12-year-old in Santa Barbara, Calif. “I found a newt in a friend’s pool,” she says. “We looked it up in an encyclopedia and realized it was a salamander. A few weeks later it still had not eaten, so we called a zoo and found out what it was and what it should be eating. I had it for eight and a half years.”
As a college student, Gabor considered a career in marine biology. “I went on a semester-abroad program to a marine research station in St. Croix, and I realized that I did not want to do marine research, but I still wanted to work with aquatic organisms,” she says. “The next summer I did research for a behavioral ecologist who studied mate choice in fish at the same field station. I found that I really enjoyed research, specifically in behavior and mate choice. But I didn’t want to have to dive every day to accomplish my research.”
She found a master’s degree program focusing on salamander behavior. “I did my master’s research on territoriality in salamanders, and part of my Ph.D. on mate choice in newts. Then, near the end of my doctoral studies, I returned to doing research on mate choice in fish, specifically mollies, which I am studying to this day. But I still love working with salamanders.”
Training Future Scientists Today, Gabor mentors graduate students of her own, as well as undergraduates.
“I try to teach freshmen how to learn in such a way that the information stays with them for a long time,” she says. “This requires putting information into a framework instead of thinking of information as independent facts, something I learned from my dad. Also, I try to teach students to apply concepts, as this promotes both greater understanding and a general way to think.”
Laura Alberici de Barbiano, Gabor’s first doctoral student focusing on mollies, agrees that this is a good approach to learning.
“She tries to make students think and gives them the tools to make general predictions rather than presenting them with a list of boring examples that they just have to regurgitate,” Alberici says. “Presenting examples within a context helps students to remember them better. Evolutionary biologists have to think about the big picture.”
Junior Michelle Parmley, one of Gabor’s undergraduates, is intrigued by the experiments with mollies.
“It is fascinating and very specialized research,” says Parmley. “Doing hands-on research with Dr. Gabor has enhanced my overall education too much to express in words. It is one thing to read about experiments; it is another thing to perform them.”
Racing to Results Before the birth of her daughter last year, Gabor competed in adventure races that combined kayaking, mountain biking and cross-country running. Athletic awards and trophies cover a wall of her office.
“I find that working out gives me a good time to think about my research without distractions,” she says. “Some of my best ideas have come while I am running. And while I’m not a great athlete, I can do well in races by training smartly and racing smartly. Instead of pounding out the miles, I try to train the smartest I can in the shortest amount of time. Before races, I visualize my stages so that I can make smooth transitions and avoid stupid mistakes. After races I feel a sense of accomplishment and then try to figure out what I can improve.
“In a sense, I do this with research too. I plan out all of the steps, perform the experiment and then spend time thinking about my results while enjoying the satisfaction of having finished another experiment.”
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