Scientists say evolution shapes ecology

TALLAHASSEE, Fla., Feb. 9 (UPI) -- U.S. scientists say an experiment with two populations of guppies shows evolution's influence on ecology can be as great as the converse.

Professors Joseph Travis of Florida State University and David Reznick of the University of California-Riverside said they studied guppies that evolved to live in upstream communities of Trinidad, and genetically distinct guppies that evolved to live downstream.

The researchers said because upstream guppies have fewer predators, they grow slowly and larger, reproduce later and less, and die older. In contrast, downstream guppies live where predators thrive, so that downstream guppies grow rapidly and smaller, reproduce quickly and die younger.

In the experiment, the team introduced downstream guppies to upstream habitats of artificial streams designed to duplicate Trinidad's natural habitats The team found the guppies made rapid and dramatic differences in the nutrient cycles and overall productivity of the stream ecosystems. Travis said the results show evolutionary change can drive changes in the ecosystem, just as ecological change can drive evolutionary changes in organisms.

"Evolution can be very fast," Travis said. "If you take downstream guppies and introduce them to pools upstream with no guppies, the descendants of those founders will evolve to look like upstream guppies in a few dozen generations."

The study appears in the online edition of the Proceedings of the National Academy of Sciences.