Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

When plants need ants’ help, bigger is better

03.05.2004


Small ant invaders put plants at peril


A Rhytidoponera aurata ant drags an acacia seed by its elaiosome, a nutritious ant snack attached to the seed.



Not surprisingly, tiny ants just can’t tote seeds as far as their bigger cousins.

Because seeds are more likely to survive and sprout if they’re farther from the mother plant, it’s best for plants to form seed-moving partnerships with heftier ants.


Now ecologists have shown how much poorer small ants are at moving seeds.

The research suggests that plants that depend on ants for heavy lifting may be in for tough times if small invasive species like Argentine or fire ants move into the neighborhood.

"Bigger isn’t just better than smaller, bigger is a lot better than smaller," said team leader Joshua Ness, an ecologist at the University of Arizona in Tucson, adding, "Most native ants are larger than invasive ants."

As invasive ants replace the native species, the average size of seed-moving ants declines. The change in the ant community can influence the plant community.

Ness and his colleagues examined 57 ant species from 24 sites across six continents and found that just a small increase in body length meant the ant was a whole lot better at carrying seeds far from the mother plant. The research article, "Ant Body Size Predicts Dispersal Distance of Ant-Adapted Seeds: Implications of Small-Ant Invasions," will be published in the May issue of the journal Ecology.

Ness’s coauthors are UA ecologist Judith L. Bronstein, Alan N. Andersen of the CSIRO Tropical Ecosystem Research Centre in Winnellie, Australia, and J. Nathaniel Holland, formerly of the University of Arizona and now at Rice University in Houston. The research was funded by the National Institutes of Health.

Ness and his colleagues study the beneficial partnerships between species. As non-native species move into new ecosystems, such mutualistic relationships can be disrupted if one partner is displaced by an invader.

Plants that rely on ants to disperse seeds generally produce a tough-coated seed that has a little ant snack, called an elaiosome, attached to it. A foraging ant picks up the seed and drags it off, often to an ant nest. The food reward gets eaten, and the discarded seed germinates in the rich soil of the colony’s trash bin.

In natural communities, such interactions between species can benefit both parties: the ant has a reliable source of food, and the plant’s seeds are dispersed far enough to reduce competition between the seedlings and their parent. The further the seeds are dispersed, the better chance the seedlings have of making it to adulthood.

Such ant-plant mutualisms are common and include such plants as sacred datura in the Southwest and violets and trilliums in deciduous forests in the eastern United States.

But how far the seed gets carried depends on the size of the ant.

Therein lies the rub.

As small invasive ants such as Argentine and fire ants move into ecosystems in the United States and throughout the world, plants are losing their traditional partners, because the invading ants displace native ants. The plants have to make do with having the new, smaller ants disperse seeds.

The smaller ants have a tendency to rob the seed of its elaiosome and then take off. They don’t lug seeds very far from the mother plants. Moreover, the small ants are more likely to leave seeds lying on the surface exposed to seed predators like rodents and other insects.

That doesn’t bode well for the plants, Ness said.

In the South African ecosystems called fynbos, many of the plants have ant-dispersed seeds. Argentine ants have invaded that ecosystem, resulting in fewer seedlings of native plants. The seedlings that do exist are not dispersed far from the parent plant.

"The invasive ants take the reward and don’t provide the level of service provided by the larger ant," Ness said.

His team’s current findings suggest that what’s happening in the fynbos is not unique to South Africa or to Argentine ants.

"We would expect the set of problems we see with Argentine ants in South Africa to occur in other habitats invaded by small ants," he said.

But knowing what problems are likely to occur can help design strategies to mitigate the effect of ant invasions, he said. For imperiled plant species, managers may need to help the plants disperse their seeds.

Ness’s next step is looking at other ways invasive ants differ from natives and how those differences change invaded communities.

Joshua Ness | EurekAlert!
Further information:
http://www.arizona.edu/

More articles from Ecology, The Environment and Conservation:

nachricht Scientists team up on study to save endangered African penguins
16.11.2017 | Florida Atlantic University

nachricht Climate change: Urban trees are growing faster worldwide
13.11.2017 | Technische Universität München

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

Im Focus: Wrinkles give heat a jolt in pillared graphene

Rice University researchers test 3-D carbon nanostructures' thermal transport abilities

Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

NASA detects solar flare pulses at Sun and Earth

17.11.2017 | Physics and Astronomy

NIST scientists discover how to switch liver cancer cell growth from 2-D to 3-D structures

17.11.2017 | Health and Medicine

The importance of biodiversity in forests could increase due to climate change

17.11.2017 | Studies and Analyses

VideoLinks
B2B-VideoLinks
More VideoLinks >>>