Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Discovery of Genetic Mutation in Florida Beach Mice Suggests Extinct Mammoth Had Light and Dark Fur

10.07.2006
Biologists at the University of California, San Diego have found that the main color differences among Florida’s mice—which are darker on the mainland, but lighter on the barrier islands to blend in with the white sand dunes—are largely due to a simple genetic mutation.

Their discovery, detailed in the July 7 issue of the journal Science, is one of the first to demonstrate how a small change in a single nucleotide—the smallest subunit of a gene—can affect the survival and evolutionary fitness of an organism in the wild.


Camouflaged beach mouse forages on the coastal sand dunes in Florida. Credit: Robert Burks

Because the mice differ not only in overall color, but in pigmentation pattern, the study also provides geneticists with a first step toward understanding how color patterns, such as zebra stripes and leopard spots, are generated in animals. And it raises the possibility that other vertebrates, such as mammoths, also evolved similar color variations using the same genetic mutation.

In a companion paper published in the same issue of Science, researchers in Germany report the discovery of this same mutation within DNA extracted from a 43,000-year-old bone of a wooly mammoth preserved in the permafrost of Siberia. Because the variations occur in the same nucleotide used by the Florida beach mice to alter their coat color, the University of Leipzig scientists say, populations of mammoths during the last Ice Age were likely composed of dark- and light-coated individuals.

“While there is growing evidence that phenotypic differences between organisms, like humans and chimps, are largely controlled by changes in gene regulation, these two studies are striking examples of how amino acid changes in structural proteins can also be important,” says Hopi Hoekstra, an assistant professor of biology at UC San Diego who headed the team that discovered the genetic roots of the color differences in Florida’s mice.

The coat pattern and color differences among populations of mice on the mainland and the barrier islands off the Florida Gulf and Atlantic coasts have been studied extensively since the 1920s, first by Francis Sumner of UCSD’s Scripps Institution of Oceanography. Sumner used the mice as a textbook example of how small, geographically isolated populations could adapt to their new environments and diverge into distinct subspecies.

Known to scientists as Peromyscus polionotus, mice living on the mainland have dark coats, which help them blend in with the vegetation and avoid their main predators—owls, hawks and herons—that hunt prey by sight. But on five barrier islands off the Florida Gulf coast and three off Northern Florida’s Atlantic coast, geographic isolation of the populations has resulted in eight distinct subspecies of beach mice, each with distinctive coat patterns that are lighter in color than their mainland counterpart.

“We know from geological evidence that the barrier islands are very recent, less than 6,000 years old,” says Hoekstra. “So these color mutations may have evolved rapidly.”

While scientists have been studying the genetics of complex coat patterns of these mice for nearly a century, few suspected that the simple mutation of a single nucleotide could have such a major impact on their coloration.

“We were surprised that this one gene could explain up to 36 percent of the variation we see in the mice,” she says. “It’s a large effect mutation. And what it says is that adaptation does not always occur gradually, but may happen in these relatively large jumps.”

Hoekstra and her colleagues—Rachel Hirschmann of UCSD’s Division of Biological Sciences and Richard Bundey and Paul Insel of UCSD’s Department of Pharmacology—discovered the single nucleotide mutation in the melanocortin-1 receptor, a gene which regulates the pigmentation of hair color.

In laboratory mating of the different subspecies to produce genetic crosses, the UCSD scientists report in their paper that the variations of this gene account as much as 36 percent of the color variation in Gulf Coast mice. Surprisingly, however, this mutation was absent in the two Atlantic Coast subspecies, even though these Atlantic coast beach mice have similarly light colored coats. The results suggest that beach mice gain their light coloration through different genetic mechanisms.

“There is apparently more than one way genetically to become a light-colored beach mouse,” says Hoekstra.

Other genes also contribute to the differences in the coat patterns among the mice. But, concedes Hoekstra, “We know very little genetically about how coat patterns are generated in mammals. This study is a first step toward understanding this complex genetic process.”

Unfortunately for the scientists, the subjects of their study are disappearing rapidly. One of the eight original subspecies studied by Sumner has since become extinct and six of the seven remaining subspecies are considered endangered because their habitats are being destroyed by human development.

“These mice exist on beautiful white-sand beaches, inhabit the sand dunes and feed on sea oats,” says Hoekstra. Their pristine habitat is being destroyed by human development coupled with hurricanes.

“Unfortunately these mice like the same habitat where people want to build beach homes and the two don’t coexist well together,” she adds. “The mice are now only found in protected areas, and hurricanes become a big threat because these beach mouse populations, which are so wonderfully adapted to their environment, are now small and fragmented.”

Funding for the study was provided by the National Science Foundation.

Comment:
Hopi Hoekstra, (858) 822-0160
Media Contacts:
Kim McDonald UCSD, (858) 534-7572
Sherry Seethaler UCSD, (858) 534-4656

Kim McDonald | EurekAlert!
Further information:
http://www.ucsd.edu

More articles from Life Sciences:

nachricht Study shines light on brain cells that coordinate movement
26.06.2017 | University of Washington Health Sciences/UW Medicine

nachricht New insight into a central biological dogma on ion transport
26.06.2017 | Aarhus University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Study shines light on brain cells that coordinate movement

26.06.2017 | Life Sciences

Smooth propagation of spin waves using gold

26.06.2017 | Physics and Astronomy

Switchable DNA mini-machines store information

26.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>