A male and female guppy in a natural stream in Trinidad.
Click on image for full size
Courtesy of Paul Bentzen

Evolution Impacts Environment, Study Finds

Biologists have long known that ecology, the interaction between organisms and their environment, plays a significant role in forming new species and in modifying living ones.

The traditional view is that ecology shapes evolution. The environment defines a template for the process of evolution: natural selection shapes organisms to fit that template.

Some studies suggest, however, that evolutionary processes reciprocate by influencing ecology.
Now biologists present evidence that ecology and evolution are indeed reciprocally interacting processes, a fundamental shift in scientists' understanding of the relationship between evolution and ecology.

The results appear this week in the online early edition of the journal Proceedings of the National Academy of Sciences (PNAS).

"By documenting that rapid, adaptive evolution within single species can cause substantial changes in ecosystem structure and function, this study makes a significant contribution to merging ecological and evolutionary theory," said Alan Tessier, program director in the National Science Foundation (NSF)'s Division of Environmental Biology, which funded the research.

NSF supported the research as part of a five-year, multi-investigator grant funded by the Frontiers in Integrative Biological Research (FIBR) initiative.

"Our results represent a first significant step in showing that evolution cannot be ignored when studying ecological interactions," said David Reznick, an evolutionary biologist at the University of California at Riverside (UCR), who led the study.

In earlier work, Reznick demonstrated that guppies, the study organism, can evolve very rapidly. In this new study he and collaborators quantify the ecological consequences of such rapid adaptation.

The scientists compared guppies--small freshwater fish that have been the subject of long-term studies--adapted to two different stream communities in Trinidad.

One stream community had a diverse group of fish species, some of which were predators on guppies. The other stream community included guppies and one or a few non-predatory species.

In the experiments, the researchers collected guppies from the two different communities and quantified their impact on a stream ecosystem by placing them in replicate, artificial streams built alongside a natural stream.

The researchers chose the locations of the artificial streams so they could divert water from a spring that flowed into the nearby natural stream. The diverted spring water first flowed through the artificial research streams, then emptied back into the natural stream.

Next, the biologists seeded the artificial streams with organisms, such as insect larvae, from the natural stream.  The artificial streams had similar ecosystems at the start of the experiment.

They found that guppies from the two types of fish communities had substantially different impacts--after only four weeks--on the structure and function of their ecosystems.

"Guppies from the more diverse fish communities ate more insect larvae, while the low-predation guppies--guppies from the simple fish communities--ate more algae," said scientist Ronald Bassar of UCR, the first author of the PNAS paper.

"These differences in diet resulted in the artificial streams with guppies from diverse communities having more algae and fewer invertebrates than streams stocked with guppies from the simple communities."

There also were corresponding differences in how and at what rate nutrients, like nitrogen and phosphorus, were recycled.

The streams with high-predation guppies--guppies from the more diverse fish communities--had less plant production and oxygen consumption, a slower breakdown of leaves that had fallen into the water, and a slower accumulation of the resulting detritus.

The researchers' findings mirrored their observations in guppies across natural streams in Trinidad.
"By doing our experiments in artificial streams we are able to pin down guppies as a likely cause of what we see in natural streams," Bassar said.

"The experiments show that local adaptation causes the evolution of differences in diet, which, in turn, causes differences in ecosystem structure. Our next step is to characterize how this changed ecosystem, in turn, shapes how the guppies adapt to it."

Bassar and Reznick were joined in the study by several biologists, including Michael Marshal and Cathy Pringle from the University of Georgia; Eugenia Zandonà of Drexel University; Douglas Fraser from Siena College; Joseph Travis from Florida State University; Alexander Flecker from Cornell University; and Steven Thomas from the University of Nebraska. The team also included Sonya Auer and Andrés López-Sepulcre of UCR.

Text above is courtesy of the National Science Foundation

Last modified May 20, 2010 by Lisa Gardiner.

You might also be interested in:

Cool It! Game

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

Biomes and Ecosystems

Biomes are large regions of the world with similar plants, animals, and other living things that are adapted to the climate and other conditions. Explore the links below to learn more about some of the...more

Triggers of Volcanic Eruptions in Oregon's Mount Hood Investigated

A new study has found that a mixing of two different types of magma is the key to the historic eruptions of Mount Hood, Oregon's tallest mountain, and that eruptions often happen in a relatively short...more

Oldest Earth Mantle Reservoir Discovered

Researchers have found a primitive Earth mantle reservoir on Baffin Island in the Canadian Arctic. Geologist Matthew Jackson and his colleagues from a multi-institution collaboration report the finding--the...more

It’s Not Your Fault – A Typical Fault, Geologically Speaking, That Is

Some geologic faults that appear strong and stable, slip and slide like weak faults. Now an international team of researchers has laboratory evidence showing why some faults that 'should not' slip are...more

Extended Period of Lower Solar Activity Linked to Changes in Sun's Conveyor Belt

A new analysis of the unusually long solar cycle that ended in 2008 suggests that one reason for the long cycle could be a stretching of the sun's conveyor belt, a current of plasma that circulates between...more

Growth Spurt in Tree Rings Prompts Questions About Climate Change

Anyone who has ever cut down a tree is familiar with the rings radiating out from the center of a tree trunk marking the tree's age. Careful study of tree rings can offer much more: a rich record of history...more

Did Life First Develop in a Mica Sandwich at the Bottom of a Primordial Sea?

Earth's first life form may have developed between the layers of a chunk of mica sitting like a multilayered sandwich in primordial waters, according to a new hypothesis. The mica hypothesis, which was...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA