warp-speed evolution is transforming ecology

Rachael Lallensack in Nature:

It took Timothy Farkas less than a week to catch and relocate 1,500 stick insects in the Santa Ynez mountains in southern California. His main tool was an actual stick. “It feels kind of brutish,” says Farkas. “You just pick a stick up off the ground and beat the crap out of a bush.” That low-tech approach dislodged hordes of stick insects that the team easily plucked off the dirt. On this hillside outside Santa Barbara, there are two kinds of bush that the stick insect (Timema cristinae) inhabits. The creature comes in two corresponding colorations: green and striped. Farkas and his fellow ecologists knew that the stick insects had evolved to blend in with their surroundings. But the researchers wanted to see whether they could turn this relationship around, so that an evolved trait — camouflage — would affect the organism’s ecology.

To find out, the team relocated mixtures of green and striped insects to different plants, so that some insects’ coloration clashed with their new home. Suddenly maladapted, these insects became targets for hungry birds, and that caused a domino effect¹. Birds drawn to bushes with mismatched stick insects stuck around to eat other residents, such as caterpillars and beetles, stripping some plants clean. “That this evolutionary force can cause local extinction is striking,” says Farkas, an ecologist at the University of New Mexico in Albuquerque. “It affects the entire community.” All this happened because of an out-of-place evolutionary trait.

Ecologists have generally ignored evolution when studying their systems; they thought it was impossible to test whether such a slow process could change ecosystems on observable timescales. But they have come to realize that evolution can happen more quickly than they assumed, and a wave of studies has capitalized on this idea to observe evolution and ecology in unison. Such eco-evolutionary dynamics could be important for understanding how new populations emerge, or for predicting when one might go extinct. Experiments suggest that evolutionary changes alter some ecosystems just as much as shifts in more-conventional ecological elements, such as the amount of light reaching a habitat. “Eco-evolutionary dynamics is the dragon lots of people are chasing right now,” says Troy Simon, an ecologist at the University of Georgia in Athens. Rapid evolution can sometimes offset some of the detrimental effects of a warming climate and other known drivers of change; in other cases, it can worsen those effects. Even for the most common processes, such as changes in population size or food chains, ecologists must take evolution into consideration, researchers say. “Everybody realized rapid evolution was occurring everywhere,” says evolutionary ecologist Andrew Hendry of McGill University in Montreal, Canada.

More here.