Travis to collaborate with team on NSF-funded study of interaction between evolution, ecology

Joseph Travis

Just how do changes in the environment cause organisms to evolve—and how do those evolving organisms then change the ecosystem?

To answer those big biology questions, the National Science Foundation (NSF) has awarded a $5 million grant over five years to an interdisciplinary research team that includes Florida State University College of Arts and Sciences Dean Joseph Travis, the FSU Robert O. Lawton Distinguished Professor of Biological Science and a noted expert in population biology.

"This award will enable experimental research on evolution in nature on an unprecedented scale to help answer a complex and critical question: Does an evolving animal affect its ecosystem in real time; that is, does the system change right along with the animal?" Travis said.

With collective expertise in molecular biology, population and community ecology, ecosystem science, biogeochemistry and applied mathematics, Travis and a dozen distinguished researchers from universities nationwide will conduct a collaborative experimental study of the natural stream communities on the island of Trinidad. They will focus on the evolution of guppies and the changes in the ecosystem that follow changes in those small freshwater fish.

Project findings are expected to shed light on how guppies have evolved in response to different ecological conditions, and in turn, how an evolving organism affects its ecosystem.

"We know that evolving organisms can alter their ecosystems in real time when the system is very simple, as with bacteria in laboratory flasks," he continued. "What we don’t know is whether those results will still emerge in more complicated natural systems in which different processes unfold at different rates."

But knowing is important, Travis said, because many animals and plants are evolving in response to the ways in which humans are changing ecosystems.

As an example, he pointed to the many fish species that appear to be evolving shorter life spans and smaller body sizes in response to over-harvesting. "Those changes could be altering the ecosystems further in a complex feedback loop that can affect whether we’ll even have fish to harvest down the line. We need to understand that loop and what it means for the future," he said.

Travis noted that groundwork for the forthcoming study was performed in Trinidad by David Reznick, an evolutionary biologist at the University of California-Riverside and the new project’s principal investigator. His findings showed that guppies living with only one predator—in this case, the killifish Rivulus hartii—have higher population densities that exert a greater effect on the food supply, resulting in less food per fish. In turn, those low-predation guppies grow more slowly, live longer, become larger in body size, and produce fewer young later in life than guppies living with many predator species—though in Trinidad, both the high-predation and low-predation sites exist in a single stream divided only by natural barrier waterfalls.

This suggests that the evolution of guppies living in two proximate but disparate sites was rapid enough in both cases to change the ecosystems in which they were evolving.

In the new Trinidad study that will encompass both experimental streams and control streams, Travis and the team first will measure ecosystem parameters such as nutrient levels and the productivity and densities of other species in the system. Then, the researchers will take guppies from high-predation sites, mark each one, place them into low-predation sites, and follow their growth, survival and reproductive success over time—assessing the expansion and evolution of the fish, the associated changes in other organisms in the community, and nutrient availability.

Ultimately, the data gathered from this and numerous other experiments over five years will aid in the development of mathematical models of the feedback loop between evolution and ecology—models, said Travis, that could be used to understand other systems as well.

"My own expertise will support our study of the growth of the populations and the changes in all of the variables across time," Travis said. "In addition, some of our FSU students will get to go to Trinidad to work on the project and develop research projects of their own. This truly is an exciting opportunity at every level."

The $5 million grant comes from NSF’s Frontiers in Integrative Biological Research (FIBR) program, which supports major research in the biological sciences that integrates scientific concepts and research tools across disciplines: biology, the physical sciences, mathematics, the social sciences, engineering and the information sciences.