Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Fossils reveal direct link between global warming and genetic diversity in wildlife

08.09.2004


For the first time, scientists have found a direct relationship between global warming and the evolution of contemporary wildlife. A research team led by Stanford University biologist Elizabeth A. Hadly published its findings in the Sept. 7 online edition of the journal PloS Biology.



"We think we know a lot about how animals might respond to global warming, but we really have very little idea about their actual genetic response to environmental change," said Hadly, an assistant professor of biological sciences at Stanford.

In the study, she and her colleagues conducted a genetic analysis of two species of rodents commonly found in Wyoming’s Yellowstone National Park – the montane vole (Microtus montanus) and the northern pocket gopher (Thomomys talpoides). The researchers collected DNA from living animals and from the teeth of fossilized specimens whose remains were buried in Lamar Cave, a remote site near the northeast entrance to the park. "The deposit in the cave is about nine yards deep and it took me seven years to excavate and identify the fossils," Hadly said. "It contains hundreds of thousands of bones and represents a continuous fossil record dating back 3,000 years. This timescale allows us to really investigate microevolution in a natural environment, the way you’d investigate it in a laboratory with something that has a much quicker generational timeline, such as bacteria or fruit flies."


Climate change and genetics

For the experiment, the research team compared DNA from voles and pocket gophers living near Lamar Cave with ancient DNA from fossilized rodents that inhabited the area at different times since 1000 B.C. The researchers were particularly interested in animals that were alive during two recent climatic events – the Medieval Warm Period (850-1350 A.D.), when the Northern Hemisphere experienced a slight warming trend; and the Little Ice Age (1350-1950), when the hemisphere cooled.

Since voles and pocket gophers prefer relatively wet grasslands, the scientists expected to see a decline in the population of both species during the Medieval Warm Period when their habitats dried up, and an increase during the Little Ice Age when the climate was wetter.

That prediction was confirmed by an analysis of fossil abundance in Lamar Cave, which revealed a 40 percent drop in the vole population during the warmer period, along with a 50 percent decline in the number of pocket gophers. As expected, fossil abundance for both species rose dramatically during the Little Ice Age as precipitation levels increased. These findings established a direct correlation between climate change and population size, but how did individual voles and pocket gophers respond genetically to these episodes of global warming and cooling?

Earlier studies have shown that, when an isolated population shrinks, inbreeding increases. As a result, surviving offspring end up with similar DNA. Over time, this lack of genetic diversity can jeopardize the entire population, because each individual inherits the same vulnerability to diseases and other external threats. "When you decrease population size, you have the potential of eliminating much genetic diversity," Hadly explained. "That’s what happened to pocket gophers during the Medieval Warm Period. We found that they underwent a population size reduction and a decline in genetic diversity, which is what you would predict."

But voles had a different response to medieval warming. "They didn’t show any reduction in genetic diversity, even though they did show a reduction in population size," Hadly said. That’s because voles routinely look for mates from other colonies. "Voles move around," Hadly noted. "They disperse quite freely, and that actually results in an elevation of genetic diversity during the time that their population sizes are undergoing reduction. Pocket gophers, on the other hand, are subterranean rodents. They dig underground burrows that are very energetically expensive to build, and they kind of stick in one place."

Subtle message

These results have important implications for wildlife biology and conservation, Hadly observed. "There’s a subtle message in this paper about the potential influence of warming on evolution," she said. "Voles show an influx of new genes and genetic diversity as their population declines, which means they’re connected to other populations. But gophers haven’t really recovered from the Medieval Warm Period, which ended less than 1,000 years ago. That means gophers are not getting any fresh, new genes from somewhere outside because they’re isolated."

While previous studies have shown that interbreeding usually occurs among large populations of animals, "this study shows that gene flow is occurring when population sizes are low," Hadly said. "So the snapshot we have today about how populations are connected may not be how it actually persists through time."

The study also has implications for wildlife managers in the greater Yellowstone ecosystem who are trying to maintain genetically diverse populations of elk, bison and other mammals. "The landscape of Yellowstone – arguably one of the largest relatively intact temperate zone ecosystems in the world – is really chopped up and isolated, and there are fewer connections between populations," Hadly explained. "They really might not have anyplace to go because of development or habitat loss, and this has the potential to be exacerbated during global warming."

She noted that the methods developed for the study offer wildlife biologists a unique approach to understanding the long-range effects of climate change on genetics. "In looking at wild organisms in nature, I don’t really know of another study like this," she said. "No one has really looked specifically at how the environment has influenced genes over a 3,000-year timescale. And our expectation is that other species will also show genetic responses to warming. Whether these effects are reversible may have to do with life history and how connected populations are, and for many species that remains to be seen."

Mark Shwartz | EurekAlert!
Further information:
http://www.stanford.edu

More articles from Life Sciences:

nachricht Symbiotic bacteria: from hitchhiker to beetle bodyguard
28.04.2017 | Johannes Gutenberg-Universität Mainz

nachricht Nose2Brain – Better Therapy for Multiple Sclerosis
28.04.2017 | Fraunhofer-Institut für Grenzflächen- und Bioverfahrenstechnik IGB

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>