In the Dec. 22 edition of Science, Andrew McAdam, an assistant professor of fisheries and wildlife at Michigan State University, outlines how red squirrels have figured out a way around the elaborate ruse trees have used to protect their crops of tasty seeds.
The study, funded in part by the National Science Foundation and the Natural Sciences and Engineering Research Council of Canada, allows scientists to track the push and pull of evolution against an unforgiving struggle for survival.
McAdam, Stan Boutin from the University of Alberta in Edmonton, Canada, and other international collaborators have been studying two different types of squirrels, which share the ‘red squirrel’ name but are only distantly related, in the forests of Canada, Belgium and Italy. The study has been going on for 20 years, with each squirrel carefully tracked.
The red squirrels on this side of the ocean dine almost exclusively on the seeds of spruce cones, which they gnaw off before the seeds ripen. The squirrels are thus a major enemy of the spruce trees. If the squirrels become too successful, their hoarding and gorging on the cones thwarts the trees’ ability to cast seeds and reproduce.
So the battle continues.
Over the years, the trees devised a strategy called masting in which they unpredictably – every few years – produce an overabundance of cones. Boutin, the study’s lead author, said it’s called a “swamp and starve” strategy to take predators by surprise, flooding the market with more seeds than the squirrels could harvest. The starve part of the strategy comes from the few cones that are produced in the years between bumper crops.Swamp and starve is designed to play to the squirrels’ weakness. Squirrels are territorial and need not only food to feed growing pups, but also a place for their offspring to call their own. When there are lots of cones, there is plenty to feed pups, but the catch is that adults also survive well so there aren’t many vacancies for young squirrels searching for a home.
What the latest paper shows is that the squirrels are on to the trees’ game, McAdam said. Prior to masting seasons, the squirrels are producing second litters – an act that would be, well, squirrelly in seasons of low food supply.
But a population boom that coincides with a seed boom is brilliant. More food means more places for juvenile squirrels to set up shop.
“What we’ve shown is that the squirrels also are playing an adaptive strategy,” McAdam said. “They’re not just following along; they’re making reproductive decisions that are best for them. This is about how red squirrels make a living in a variable world and how they make reproductive decisions in what seems like unpredictability. And given the currency they use, the stakes are high.”
Boutin speculates that buds the spruce trees put out the summer before cones develop may hold the clues to a masting event. These buds differentiate in the summer; some become tree branches, some develop into cones. The squirrels eat the buds and may detect which destiny they’ll follow thus getting a tip-off to an upcoming masting event.
“I hope this gives people a better appreciation that these squirrels are not just taking what they get,” McAdam said. “Both players – the squirrels and the trees – are following these strategies to try to maximize their fitness.”
Andrew McAdam | EurekAlert!
Closing the carbon loop
08.12.2016 | University of Pittsburgh
Newly discovered bacteria-binding protein in the intestine
08.12.2016 | University of Gothenburg
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
08.12.2016 | Life Sciences
08.12.2016 | Physics and Astronomy
08.12.2016 | Materials Sciences