Brightsurf Science News and Current Science News Events
 
Email a Friend Send to a friend
Printer Friendly Print Pendulums, predators and prey: The ecology of coupled oscillations

Pendulums, predators and prey: The ecology of coupled oscillations

December 04, 2006

ANN ARBOR, Mich.--Connect one pendulum to another with a spring, and in time the motions of the two swinging levers will become coordinated.

This behavior of coupled oscillators--long a fascination of physicists and mathematicians--also can help biologists seeking to understand such questions as why some locations overflow with plants and animals while others are bereft, University of Michigan theoretical ecologist John Vandermeer maintains.




In the cover article for the December issue of the journal BioScience, Vandermeer summarizes theoretical work he has done over the past decade, leading to his conclusion that ecologists seeking to understand complex interactions in nature should pay closer attention to coupled oscillations.

The basic idea of oscillating populations is not new to ecology.

"We know that any predator-prey system, say lions and zebras for example, shows oscillations," said Vandermeer, who is the Margaret Davis Collegiate Professor of Ecology and Evolutionary Biology. "If there are lots of lions preying on zebras, numbers of zebras decline; then because zebras are scarce, lions starve and their numbers dwindle, allowing the zebra population to build up again. You see this oscillation, changing on a regular basis from lots of predators with few prey to lots of prey with few predators. The pattern is like waves or pulsations."

What gets interesting is when two independently oscillating systems, such as lions preying on zebras and cheetahs preying on impalas, become connected through the invasion of a third predator--leopards, for instance.

"When they become connected, the situation is very much like connecting two springs together--the ups and downs get into regular patterns." In the case of lions, cheetahs and leopards, bringing leopards into the system causes lion and cheetah populations to oscillate in phase with each other--peaking and declining at the same time. That works to the leopard's advantage--when both lion and cheetah populations are low, leopards can pounce on the plentiful prey. But then lions and cheetahs increase again, eventually building up their numbers and combined competitive strength enough to drive out the leopards--at least until the next low point in the lions' and cheetahs' population cycles.

Predator-prey systems can also become coupled when a new prey species invades and competes for resources with prey species in two previously unconnected predator-prey systems. For example, an extremely fast antelope might begin competing with zebras and impalas for food. Even though neither lion nor cheetah is fast enough to prey on the new antelope, the antelope's activity links the previously unconnected lion-zebra and cheetah-impala pairs. In such a case, the ups and downs of the two original prey species are thrown into chaotic but coordinated patterns, Vandermeer said.

"That's what's known as coordinated chaos--a phenomenon that occurs in some physical systems, such as lasers, but hadn't been pointed out in ecology before." By oscillating out of phase with the other two grazers--zebras and impalas--the antelope can coexist with them, prospering when their numbers are low.

Considering such scenarios with the aid of mathematical simulations such as Vandermeer's can help address questions biologists have wrestled with for decades, such as how species that appear to be exploiting the same resources can coexist and why some predator-prey systems are particularly resistant to invaders.

"In the past, ecologists have taken a traditional Newtonian view of the world, where everything comes into a nice equilibrium," Vandermeer said. "But oscillations sometimes destroy that equilibrium. What I'm suggesting is that we ecologists need to acknowledge the inherent oscillation in consumer-resource systems, such as predator-prey, herbivore-plant and parasite-host systems, and start approaching these old ecological issues in terms of coupled oscillators."

University of Michigan



Related Ecology News Articles Ecology News and Current Ecology Events RSS Ecology News and Current Ecology Events RSS
Genome of saltwater creature could aid understanding of gene grouping
The genetic code of a simple saltwater creature could help researchers learn more about how groups of genes function in humans and other species.

Study finds foul owls use feces to show they are in fine feather
Some years ago, within the Department of Conservation Biology of the Estación Biológica de Doñana (EBD-Consejo Superior de Investigaciones Científicas; Seville, Spain), a recently established group (colloquially named the Night Ecology Group) started to explore the possibility of visual communication in crepuscular and nocturnal birds.

New and improved test for West Nile virus in horses
A new test for West Nile virus in horses that could be modified for use on humans and wildlife may help track the spread of the disease, according to an article in the September issue of the Journal of Medical Microbiology.

Signals from the Atlantic Salmon Highway
For years scientists have struggled to understand the decline and slow recovery of Atlantic salmon, a once abundant and highly prized game and food fish native to New England rivers. Biologists agree that poor marine survival is affecting salmon in the U.S. and Canada, but specific causes are difficult to determine in the ocean. Small acoustic tags and associated technology may provide some answers.

Extinction most likely for rare trees in the Amazon rainforest
Common tree species in the Amazon will survive even grim scenarios of deforestation and road-building, but rare trees could suffer extinction rates of up to 50 percent, predict Smithsonian scientists and colleagues in the Aug. 12 issue of the journal Proceedings of the National Academy of Science.

Microbes, by latitudes and altitudes, shed new light on life's diversity
Microbial biologists, including the University of Oregon's Jessica L. Green, may not have Jimmy Buffett's music from 1977 in mind, but they are changing attitudes about evolutionary diversity on Earth, from oceanic latitudes to mountainous altitudes.

Testosterone key to disease transmission
High levels of testosterone may be a key factor in spreading disease among mice, according to biologists. The findings could help explain why males in a population are often more likely to get infected, and transmit disease.

A one-stop shop for minimal information standards
More than 20 grass-roots standardisation groups, led by scientists at the European Bioinformatics Institute (EMBL-EBI) and the Centre for Ecology & Hydrology (CEH), have combined forces to form the "Minimum Information about a Biomedical or Biological Investigation" (MIBBI) initiative (www.mibbi.org).

The drivers of tropical deforestation are changing, say scientists
A shift from poverty-driven to industry-driven deforestation threatens the world's tropical forests but offers new opportunities for conservation, according to an article coauthored by William Laurance of the Smithsonian Tropical Research Institute in Panama.

Entomologists play matchmakers for cerambycid beetles
Cerambycid beetles, also known as long-horned beetles, can cause severe damage to standing trees, logs and lumber. How then might they be promptly detected and their numbers swiftly controlled?
More Ecology News Articles


The Omnivore's Dilemma: A Natural History of Four Meals
by Michael Pollan

A New York Times bestseller that has changed the way readers view the ecology of eating, this revolutionary book by award winner Michael Pollan asks the seemingly simple question: What should we have for dinner? Tracing from source to table each of the food chains that sustain us—whether industrial or organic, alternative or processed—he develops a portrait of the American way of eating. The...



Cradle to Cradle: Remaking the Way We Make Things
by William McDonough, Michael Braungart

Paper or plastic? Neither, say William McDonough and Michael Braungart. Why settle for the least harmful alternative when we could have something that is better--say, edible grocery bags! In Cradle to Cradle, the authors present a manifesto calling for a new industrial revolution, one that would render both traditional manufacturing and traditional environmentalism obsolete. Recycling, for...



Ishmael: An Adventure of the Mind and Spirit
by Daniel Quinn

The narrator of this extraordinary tale is a man  in search for truth. He answers an ad in a local  newspaper from a teacher looking for serious  pupils, only to find himself alone in an abandoned  office with a full-grown gorilla who is nibbling  delicately on a slender branch. "You are the  teacher?" he asks incredulously. "I am  the teacher," the gorilla replies. Ishmael is  a creature of...



1491: New Revelations of the Americas Before Columbus
by Charles C. Mann

1491 is not so much the story of a year, as of what that year stands for: the long-debated (and often-dismissed) question of what human civilization in the Americas was like before the Europeans crashed the party. The history books most Americans were (and still are) raised on describe the continents before Columbus as a vast, underused territory, sparsely populated by primitives whose cultures...



Bird Songs: 250 North American Birds in Song
by Les Beletsky

Drawing from the collection of the world-renowned Macaulay Library at the Cornell Lab of Ornithology, Bird Songs presents the most notable North American birds including the rediscovered Ivory-billed Woodpecker in a stunning new format. Renowned bird biologist Les Beletsky provides a succinct description of each of the 250 birds profiled, with an emphasis on their distinctive songs. Lavish...



Silent Spring
by Rachel Carson

Silent Spring, released in 1962, offered the first shattering look at widespread ecological degradation and touched off an environmental awareness that still exists. Rachel Carson's book focused on the poisons from insecticides, weed killers, and other common products as well as the use of sprays in agriculture, a practice that led to dangerous chemicals to the food source. Carson argued that...



The Botany of Desire: A Plant's-Eye View of the World
by Michael Pollan

Working in his garden one day, Michael Pollan hit pay dirt in the form of an idea: do plants, he wondered, use humans as much as we use them? While the question is not entirely original, the way Pollan examines this complex coevolution by looking at the natural world from the perspective of plants is unique. The result is a fascinating and engaging look at the true nature of domestication. In...



The Lorax (Classic Seuss)
by Dr. Seuss, Theodor Seuss Geisel

When Dr. Seuss gets serious, you know it must be important. Published in 1971, and perhaps inspired by the "save our planet" mindset of the 1960s, The Lorax is an ecological warning that still rings true today amidst the dangers of clear-cutting, pollution, and disregard for the earth's environment. In The Lorax, we find what we've come to expect from the illustrious doctor: brilliantly whimsical...



Plan B 3.0: Mobilizing to Save Civilization, Third Edition
by Lester R. Brown

"How to build a more just world and save the planet....We should all heed Brown's advice."—Bill ClintonIn this updated edition of the landmark Plan B, Lester Brown outlines a survival strategy for our early twenty-first-century civilization. The world faces many environmental trends of disruption and decline, including rising temperatures and spreading water shortage. In addition to these...



Blessed Unrest: How the Largest Social Movement in History Is Restoring Grace, Justice, and Beauty to the World
by Paul Hawken

The New York Times bestselling examination of the worldwide movement for social and environmental change Paul Hawken has spent more than a decade researching organizations dedicated to restoring the environment and fostering social justice. From billion-dollar nonprofits to single-person dot.causes, these groups collectively comprise the largest movement on earth, a movement that has no name,...

© 2008 BrightSurf.com