Members of Hillis Lab Receive NSF Grant

Central Texas salamanders of the Eurycea clade are enigmatic amphibians that live in dark underground water systems. This sort of habitat has given rise to a number of phenotypes of these salamanders, one of which is the focus of a new National Science Foundation (NSF) grant awarded to David Hillis and members of his lab in the Department of Integrative Biology, in collaboration with Dana Garcia from Texas State University.

Ruben Tovar, graduate student, and Tom Devitt, Research Scientist, will be leading the three-year investigation. The goal of this grant is to understand the evolutionary, developmental, and molecular underpinnings responsible for convergence--the independent evolution of similar traits in different species--in Central Texas salamanders.

For these groundwater salamanders, it has long been thought that when organisms like them live in a perpetually-dark subterranean habitat, they eventually will all evolve similar traits over time due to natural selection. With even just a superficial glance to several species of cave and aquifer vertebrates and invertebrates, one can indeed see these extreme phenotypes: reduced pigmentation, elongated limbs, flattened, shovel-like heads, and reduced eyes. So, it’s easy to state that they look the same because they have adapted to living in dark, subterranean habitats.

Tovar, who has made this project the focus of his PhD work, wants to dig deeper. “It’s all been kind of relative until now,” says Tovar. “Meaning, their eyes look relatively reduced to their heads and to other closely-related species that live above ground. But no one has really gone in to understand if it’s a completely reduced eye, and how reduced is it? What kind of tissues remain?”

Tovar has already jump started the search for answers to these questions before receiving the NSF grant. Since beginning his PhD work in the Hillis lab, Ruben has been collecting a number of salamander populations. His previous master’s research looked at the Texas blind salamander and its extremely reduced eyes. What he learned is that the eye of the Texas blind salamander doesn’t have some of the key features needed for sight, as it doesn’t have a lens or fully-formed retina. But features of other groundwater salamander visual systems are still unknown. No one knows what the Austin blind salamander’s eye structure is composed of, not to mention how they develop.

With the NSF grant, now Tovar can look at many species of Central Texas salamanders to learn how far reaching convergence exists in them. Currently, he has a handful of cave representatives they have started working with already: the Honey Creek Cave salamander (Eurycea latitans) and Preserve Cave salamander (Eurycea pterophila). Beyond these populations, Tovar plans to both collect and breed several representatives of subterranean phenotypes. Looking at their offspring, he can ask questions about what kind of molecular and developmental underpinnings result in a reduced eye. Are the offspring developing in similar ways to reach the ultimate outcome of a reduced eye like their parents were?

Through the Freshman Research Initiative: Biodiversity Discovery, Devitt plans to integrate undergraduates into the research, beginning next summer. Students from UT and Texas State will take part in a research exchange program where they will learn to think like scientists and experience what it’s really like to be a researcher, from hypothesis formation, data collection, and fieldwork, followed by labwork, analysis, and writing.