Mice living in sandy hills quickly evolved lighter coloration
August 27, 2009
As the result of natural selection for crypsis, deer mice (Peromyscus maniculatus) living on the pale soils of the Nebraska Sand Hills are lighter (top) than deer mice from darker, surrounding areas (bottom). Mice are shown on contrasting soil backgrounds (bottom: Sand Hills soil; top: soil from outside the Sand Hills). Credit: Photos by Emily Kay.
In a vivid illustration of natural selection at work, scientists at Harvard University have found that deer mice living in Nebraska's Sand Hills quickly evolved lighter coloration after glaciers deposited sand dunes atop what had been much darker soil. The work is described this week in the journal Science.
Co-authors Catherine R. Linnen and Hopi E. Hoekstra show that the different variants of a single gene determines whether a deer mouse is dark or pale -- a small difference with huge survival implications for a species widely hunted by owls, hawks and other visual predators.
"Our work shows that rapid adaptive change, such as the evolution of lighter coloration among Sand Hills mice, need not always rely on pre-existing genetic variation," says Linnen, a postdoctoral researcher in Harvard's Department of Organismic and Evolutionary Biology. "We show that a single genetic change creates lighter coloration in these mice, and that this variant clearly arose recently, sometime after the formation of the Sand Hills."
The color of this deer mouse's (Peromyscus maniculatus) coat allows it to blend into the light soil of the Nebraska Sand Hills and help escape detection by visual predators, such as owls and hawks. Credit: Emily Kay
The species Linnen and Hoekstra studied, Peromyscus maniculatus, is the most widespread mammal in North America. By analyzing the strength of natural selection in favor of lighter Sand Hills mice, the scientists determined that predation would drive virtually all individuals in the area toward pale coloration within 8,000 years -- just slightly less than the age of the Sand Hills.This and other evidence, including much greater genetic uniformity among pale mutants than their dark wildtype cousins, suggests this mutation is a relatively recent development, likely arising shortly after the formation of the Sand Hills in north-central Nebraska.
Linnen and Hoekstra found that light coloration arises from increased activity in a single gene, called Agouti. This increased expression, in turn, is associated with the deletion of a single amino acid, a process that appears to be under natural selection. This Agouti mutation generates wider pale bands on dorsal hairs, making the entire animal appear golden rather than brown.
"This work sheds new light on the forces affecting diversity in nature," says Hoekstra, John L. Loeb Associate Professor of the Natural Sciences in Harvard's Faculty of Arts and Sciences. "It's an exciting time in biology, with the integration of field studies, genetic analysis, and developmental and molecular biology enabling us to connect genes and molecular mechanisms with species' traits in the wild. In the bicentennial of Charles Darwin's birth and on the 150th anniversary of his publication of On the Origin of Species, this study vividly illustrates the power of natural selection."
The Sand Hills, rolling dunes occupying more than a quarter of Nebraska's area, were created by glacial deposition of sand sometime in the last 10,000 years. Since the soils of these hills are composed mostly of light-colored quartz grains, pale mice are better camouflaged against owls and other raptors. Surrounding areas, with much darker soils, tend to be occupied by dark brown mice.
By mating light Sand Hills mice and dark mice found outside the Sand Hills, Linnen and Hoekstra determined that the light coloration seen in Agouti mutants is genetically dominant to the darker coats seen among wildtype mice.
Source: Harvard University (news : web)
Aug 14, 2007 |
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The two variants are too close together geographically to speciate. 8,000 years might be enough IF they didn't interbreed at the edges of the territories, which they most likely do. Without some way to stop interbreeding speciation is unlikely.
Ethelred
Sorry for the new signature. But It Needed Killun.
From QubitTamer's fake profile
Qubitwit gets the rest of August in my signature for aiming his idiocy at me. Again.
Please keep my sig all the way through 2009 jackass.
Learn to read. I can't even tell what Slotin/Alexa-Alazee opinion is on this. I don't much care either.
It is natural selection. If you don't like it show cause.
And yes you are sill owned in my sig till the end of the Month. The Briar Patch will retain you till then.
Even jackasses have enough brains not to think a spammer made a meaning post. Perhaps you should hire one to do your thinking for you.
Ethelred
Sorry for the new signature. But It Needed Killun.
From QubitTamer's fake profile
Qubitwit gets the rest of August in my signature for aiming his idiocy at me. Again.
I am here to tell you to get the hell off the computer and go out and find another human being who needs some help or assistance with something. Go volunteer to cook meals at a shelter, just DO SOMETHING WITH YOUR LIFE. That is NOT a message from a God or based off any religion, it's based on the observation that people of high energy and intellect have a RESPONSIBILITY to use those gifts in the service of others. You are WASTING your life (58 eh? You act more like a 22 year old) I bet i have been more places and done more things in my much shorter life than you so i shall continue to consider you sad and pathetic and really nothing more than a whiny curmudgeon if you are in fact 58 as you claim to be)
Physorg banned him again. So they disagree with you and agree with me.
I see you still haven't done a search on Oliver. Neither Alexa or I nor even you have much in common with him. Well maybe you do but I am hoping there aren't that many Olivers out there still.
Know thyself.
You sure are making it easy to reuse my other posts.
Thank you.
I will not be punched, stamped, folded briefed debriefed or numbered. My life is my own.
Better twenty two than 14 or for that matter 58. Somewhere between 22 and 28 would be about ideal for me.
You seem to be using a lot of time here trying to troll me. Get out more often.
Stay out of in front of trucks.
Considering the alternative I will take 58 any day of the week until I turn 59. Then I will take that for a year.
I am having fun. You are trolling me and losing. More fun.
You are on your second week of obsessing about me. So it is pretty clear just who is owned.
I believe the phrase 'get a life' applies to you. But don't bother if you don't want too.
And thank you for being so predictable. Typical of trolls on every site.
Begging will still not avail you. You stay in my sig till the end of the month. Obsess all you want. Prove my point for me.
Oh and the right to way to slit your wrists is along the arm and not across. Running around the block might help but the guy that did finally called the a hospital and survived.
Though in your case just staying till sunrise should do the trick.
Ethelred
Sorry for the new signature. But It Needed Killun.
From QubitTamer's fake profile
Qubitwit gets the rest of August in my signature for aiming his idiocy at me. Again.
Please stick with the subject at hand and keep this nonsense private. Exchange e-mails, phonenumbers or whatever. I don't think anyone here cares for these rather childish arguments, so stop it please.
on topic:
This is indeed a good example of the power of natural selection. Very interesting to read!
Meow