College of Science

Biology doctoral student Beston receives prestigious NSF Doctoral Dissertation Improvement Grant funding

A doctoral student at The University of Texas at Arlington has received a prestigious National Science Foundation award to help fund her research.

Shannon Beston, a third-year Ph.D. student in biology, was selected to receive funds from the NSF’s Doctoral Dissertation Improvement Grants (DDIG) program, which typically awards funding to only 100-200 projects nationwide each year. Beston, who works in the lab of Matt Walsh, assistant professor of biology, learned that she had been named a DDIG recipient while doing research for her dissertation on the Caribbean island of Trinidad in January.

“We had just gotten back to the field station for the day and I received an e-mail from my program officer asking for me to give her a call back as soon as I could,” Beston said. “When she told me that I received the grant, I was thrilled. At the start of the trip I knew that there was a possibility that it might be my last time doing fieldwork on the island because we no longer had funds to support future travel. I was very excited about the DDIG because it was my first NSF grant, but a lot of that excitement was because I knew that with this grant I could return to Trinidad and could continue to test some of the questions I am most interested in answering.”

The DDIG award, which is for $19,604, will fund Beston’s dissertation project, titled “The evolution of complexity: tests of the ecological drivers of eye size and brain size evolution in nature”, which examines the evolution of complex traits in natural populations. Specifically, the work addresses how eyes and brains have evolved in response to predation in populations of killifish, Rivulus hartii, found in the waters of the Caribbean off the island of Trinidad.

“Understanding how complex traits have evolved is a long-standing goal in evolutionary biology and the complex structure of the eye is frequently presented as an example of evolution that challenges the understanding of evolution by natural selection,” said Beston, who earned a B.S. in Biology at Hobart and William Smith Colleges in Geneva, N.Y., in May 2014 prior to coming to UTA to begin her doctoral studies.

While eye size varies extensively across species, there are very few studies that have evaluated how eyes evolve within a single species, she explained. Increases in eye size are associated with improved vision. As a result, shifts in eye size are likely connected, and potentially driven, by a variety of ecological factors, such as foraging, avoiding predators, and identifying mates. Rivulus are found in fish communities on the island that vary in predation intensity, ranging from sites where they are preyed upon by large piscivorous fish to sites where they are the only species present.

“My most recent work, and the basis of the research I have proposed in the DDIG, has shown that increases in predation are associated with genetically based decreases in eye size,” Beston said. “This work provides a clear link between an ecological driver of eye size evolution (i.e. predation), but it does not establish causation. We still do not know why predators appear to select for a smaller eye size in Rivulus.”

Beston hopes that the research she has proposed in the DDIG will begin to provide answers that establish a causal link between predators and prey eye size, rather than just a correlational relationship. The work she proposed involves a series of mark-recapture experiments where individual Rivulus specimens
Shannon Beston

can be tracked both from populations with predators and without predators to look at how eye size correlates with variables like survival and growth rate.

“I also plan to complete perturbation experiments in the lab and in nature,” she said. “These approaches will evaluate how natural selection is operating on eye size and will also allow us to experimentally test the influence of predators on eye size in Rivulus.”

Walsh said the funding from the DDIG will allow Beston to perform “ambitious, manipulative experiments in nature that have the potential to provide novel insights into how the vertebrate eye evolves.”

“Shannon has shown tremendous growth as a Ph.D. student at UTA and is always willing to go the extra mile in the field and lab,” Walsh said. “Her selection as a recipient of an NSF DDIG grant reflects the success she has achieved to date as well as the strong potential for continued success thereafter.”

Beston plans to return to Trinidad to collect more specimens in August and December, as well as making several return trips in 2018, which will be paid for by her DDIG award.

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Posted April 17, 2017