Featured Research

from universities, journals, and other organizations

Chipmunks Descended From Ancestors That Survived Last Ice Age, Scientists Say

Date:
July 13, 2004
Source:
University Of Illinois At Urbana-Champaign
Summary:
Eastern chipmunks have upset the apple cart of assumptions on glacier-driven population migrations. Based on a mitochondrial DNA analysis of 244 chipmunks, it seems the majority of them living in Illinois and Wisconsin today descend from ancestors who survived the last North American ice age.

CHAMPAIGN, Ill. -- Well, nuts.

Related Articles


Eastern chipmunks (Tamias striatus) have upset the apple cart of assumptions on glacier-driven population migrations. Based on a mitochondrial DNA analysis of 244 chipmunks, it seems the majority of them living in Illinois and Wisconsin today descend from ancestors who survived the last North American ice age in what researchers believe were isolated pockets of forestland amid the cold tundra.

The findings -- reported online this week (July 12-16) ahead of regular publication by the Proceedings of the National Academy of Sciences -- came as a surprise to researchers at the University of Illinois at Urbana-Champaign and the Illinois Natural History Survey.

They found that 78 of the 95 haplotypes (groups of individuals with similar sequences of base pairs of genetic material) identified in mostly the Wisconsin and Illinois populations clearly descend from survivors in the west and north, closer to the Wisconsin glaciation. Over time, these chipmunks migrated south from the colder region, merging with chipmunks that migrated into the region from the warmer east and south.

"This is counter-intuitive given that organisms would be expected to respond to glacial expansion by shifting their ranges to more suitable climates most often in a southern refuge followed by a northward recolonization as the glaciers receded," said Kevin C. Rowe, lead author and doctoral student in the evolutionary/molecular biology laboratory at the U. of I.

"It also is particularly surprising that while chipmunks in Illinois and Wisconsin are closely related, they are distantly related to chipmunks in Indiana and Michigan," he said. "There really is no clear geographical barrier at present that should lead to their isolation, so chipmunk history may be responsible. From our data, this history appears to include colonization of the Midwest from multiple sources such as separate ice-age refugia."

Unlike nuclear DNA that passes along vital genetic information, mitochondrial DNA is found in organelles and generates energy. It has been used to trace genetic lineage. In this case, researchers focused on a mitochondrial region called the D-loop, a highly variable one that opens a window on geographical time and distribution of organisms.

DNA was taken from tissue from the very tip of an ear of each chipmunk after the animals were captured in live traps. The chipmunks were released at the same sites of their capture. The DNA, from which 964 unambiguous base pairs were identified, was then analyzed for evolutionary relationships, with 95 unique haplotypes being identified.

Only 17 of the haplotypes were identified as from eastern clades, or groups descending from multiple eastern and southern populations, that included northern Michigan through Indiana and eastern and southern Illinois. The other 78 haplotypes, whose genetic sequences showed little divergence, were found primarily in chipmunks from northern Wisconsin to southern Illinois.

The data, the researchers write, "indicate that T. striatus from Wisconsin and Illinois are descended from a population that has recently expanded out of a small glacial refugium."

That refugium refers to northern regions up against the ice sheets "in an area known as the 'driftless region,' from where the chipmunks that currently inhabit Wisconsin and Illinois emerged from surviving deciduous forest areas and moved south as the glaciers receded," Rowe said.

The Wisconsin glaciation occurred about 18,000 years ago during the Late Pleistocene, with the Laurentide Ice Sheet gradually receding from its southern reaches. Researchers had long thought that the driftless region near the ice sheets were all tundra, but emerging geological evidence now suggests that small areas of deciduous forests may have persisted, allowing for some animals to survive.

"Overall, in light of global climate change occurring today, our results indicate that predictions of movements and where organisms may or may not end up will not be as straightforward as the literature up to now has led one to believe," said co-author Ken N. Paige, head of the animal biology department at the U. of I.

Other co-authors were Edward J. Heske of the Center for Wildlife Ecology unit of the Illinois Natural History Survey and Patrick W. Brown, formerly at the Natural History Survey and now of Michigan State University Extension. The American Museum of Natural History, American Society of Mammalogists and National Science Foundation funded the project.


Story Source:

The above story is based on materials provided by University Of Illinois At Urbana-Champaign. Note: Materials may be edited for content and length.


Cite This Page:

University Of Illinois At Urbana-Champaign. "Chipmunks Descended From Ancestors That Survived Last Ice Age, Scientists Say." ScienceDaily. ScienceDaily, 13 July 2004. <www.sciencedaily.com/releases/2004/07/040713082558.htm>.
University Of Illinois At Urbana-Champaign. (2004, July 13). Chipmunks Descended From Ancestors That Survived Last Ice Age, Scientists Say. ScienceDaily. Retrieved April 19, 2015 from www.sciencedaily.com/releases/2004/07/040713082558.htm
University Of Illinois At Urbana-Champaign. "Chipmunks Descended From Ancestors That Survived Last Ice Age, Scientists Say." ScienceDaily. www.sciencedaily.com/releases/2004/07/040713082558.htm (accessed April 19, 2015).

Share This


More From ScienceDaily



More Earth & Climate News

Sunday, April 19, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Nervous Return to Everest a Year After Deadly Avalanche

Nervous Return to Everest a Year After Deadly Avalanche

AFP (Apr. 18, 2015) In the Himalayan town of Lukla, excitement mingles with fear as mountaineers make their way up to Everest a year after an avalanche killed 16 guides and triggered an unprecedented shut-down of the world&apos;s highest peak. Duration: 00:37 Video provided by AFP
Powered by NewsLook.com
L.A. Water Cops Remind Residents of Water Conservation

L.A. Water Cops Remind Residents of Water Conservation

Reuters - US Online Video (Apr. 18, 2015) "Water cops" in Los Angeles remind the public about water conservation methods amid California&apos;s prolonged drought. Julie Noce reports. Video provided by Reuters
Powered by NewsLook.com
Planet Defence Conference Tackles Asteroid Threat

Planet Defence Conference Tackles Asteroid Threat

AFP (Apr. 17, 2015) Scientists gathered at a European Space Agency (ESA) facility outside Rome this week for the Planetary Defence Conference 2015 to discuss how to tackle the potential threat from asteroids hitting Earth. Duration: 00:54 Video provided by AFP
Powered by NewsLook.com
Gulf Scarred, Resilient 5 Years After BP Spill

Gulf Scarred, Resilient 5 Years After BP Spill

AP (Apr. 17, 2015) Five years after the Deepwater Horizon spill in the Gulf of Mexico, splotches of oil still dot the seafloor and wads of tarry petroleum-smelling material hide in pockets in the marshes of Barataria Bay. (April 17) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins