Religions > Atheism > Pressured by predators, lizards see rapid shift in natural selection
| Topic: |
Religions > Atheism |
| User: |
"johac" |
| Date: |
17 Nov 2006 01:51:36 AM |
| Object: |
Pressured by predators, lizards see rapid shift in natural selection |
Natural selection can be studied experimentally and can work fast.
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Pressured by predators, lizards see rapid shift in natural selection
CAMBRIDGE, Mass. -- Countering the widespread view of evolution as a
process played out over the course of eons, evolutionary biologists have
shown that natural selection can turn on a dime -- within months -- as a
population's needs change. In a study of island lizards exposed to a new
predator, the scientists found that natural selection dramatically
changed direction over a very short time, within a single generation,
favoring first longer and then shorter hind legs.
The findings, by Jonathan B. Losos of Harvard University and colleagues,
are detailed this week in the journal Science. Losos did much of the
work before joining Harvard earlier this year from Washington University
in St. Louis.
"Because of its epochal scope, evolutionary biology is often caricatured
as incompatible with controlled experimentation," says Losos, professor
of organismic and evolutionary biology in Harvard's Faculty of Arts and
Sciences and curator in herpetology at the Harvard Museum of Comparative
Zoology. "Recent work has shown, however, that evolutionary biology can
be studied on short time scales and that predictions about it can be
tested experimentally. We predicted, and then demonstrated, a reversal
in the direction of natural selection acting on limb length in a
population of lizards."
Losos and colleagues studied populations of the lizard Anolis sagrei on
minuscule islands, or cays, in the Bahamas. They introduced to six of
these cays a larger, predatory lizard (Leiocephalus carinatus) commonly
found on nearby islands and known as a natural colonizer of small cays.
The scientists kept six other control cays predator-free and
exhaustively counted, marked, and measured lizards on all 12 isles.
Anolis sagrei spends much of its time on the ground, but previous
research has shown that when a terrestrial predator is introduced, these
lizards take to trees and shrubs, becoming increasingly arboreal over
time. Losos and his colleagues hypothesized that immediately following a
predator's arrival, longer-legged -- and hence faster-running -- Anolis
lizards would be favored to elude capture. However, as the lizards grew
ever more arboreal in habitat, the scientists projected that natural
selection would begin to favor shorter limbs, which are better suited to
navigating narrow branches and twigs.
Their hypothesis was borne out. Six months after the introduction of the
predator, Losos found that the Anolis population had dropped by half or
more on the islands with the predators, and in comparison to the lizards
on the predator-free islands, long legs were more strongly favored:
Survivors had longer legs relative to non-survivors. After another six
months, during which time the Anolis lizards grew increasingly arboreal,
selective pressures were exactly the opposite: Survivors were now
characterized by having shorter legs on the experimental islands as
compared to the control islands.
The behavioral shift from the ground to higher perches apparently caused
this remarkable reversal, Losos says, adding that behavioral flexibility
may often drive extremely rapid shifts in evolution.
"Evolutionary biology is by its nature an historical science, but the
combination of microevolutionary experimentation and macroevolutionary
historical analysis can provide a rich understanding about the genesis
of biological diversity," the researchers write.
---
http://www.eurekalert.org/pub_releases/2006-11/hu-pbp111406.php
--
John Hachmann aa #1782
"Those who can make you believe absurdities can make you commit atrocities"
-Voltaire
Contact - Throw a .net over the .com
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| User: "*nemo*" |
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| Title: Re: Pressured by predators, lizards see rapid shift in natural selection |
17 Nov 2006 05:30:20 AM |
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In article <jhachmann-A45404.23513616112006@news.giganews.com>,
johac <jhachmann@sbcglobal.com> wrote:
CAMBRIDGE, Mass. -- Countering the widespread view of evolution as a
process played out over the course of eons, evolutionary biologists have
shown that natural selection can turn on a dime -- within months -- as a
population's needs change. In a study of island lizards exposed to a new
predator, the scientists found that natural selection dramatically
changed direction over a very short time, within a single generation,
favoring first longer and then shorter hind legs.
If you think evolution can move fast for lizards there, check out my
home town.
http://news.yahoo.com/s/ap/20061117/ap_on_fe_st/alligator_motel_2
Damn things are so advanced here, they're staying in local hotels now.
{;-)
--
Nemo - EAC Commissioner for Bible Belt Underwater Operations.
Atheist #1331 (the Palindrome of doom!)
BAAWA Knight! - One of those warm Southern Knights, y'all!
Charter member, SMASH!!
http://home.earthlink.net/~jehdjh/Relpg.html
Draco Dormiens Nunquam Titillandus
Quotemeister since March 2002
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| User: "Randy Day" |
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| Title: Re: Pressured by predators, lizards see rapid shift in natural selection |
17 Nov 2006 06:20:21 AM |
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*nemo* wrote:
In article <jhachmann-A45404.23513616112006@news.giganews.com>,
johac <jhachmann@sbcglobal.com> wrote:
CAMBRIDGE, Mass. -- Countering the widespread view of evolution as a
process played out over the course of eons, evolutionary biologists have
shown that natural selection can turn on a dime -- within months -- as a
population's needs change. In a study of island lizards exposed to a new
predator, the scientists found that natural selection dramatically
changed direction over a very short time, within a single generation,
favoring first longer and then shorter hind legs.
If you think evolution can move fast for lizards there, check out my
home town.
http://news.yahoo.com/s/ap/20061117/ap_on_fe_st/alligator_motel_2
Damn things are so advanced here, they're staying in local hotels now.
{;-)
Heh. Gives a *whole* new meaning to the term
"lounge lizard".
--
R
Atheist Chair,
EAC Disciplinary Committee
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| User: "johac" |
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| Title: Re: Pressured by predators, lizards see rapid shift in natural selection |
18 Nov 2006 12:57:34 AM |
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In article <nemo0037-5D71D7.06301917112006@news.west.earthlink.net>,
*nemo* <nemo0037@earthlink.dieSPAM.net> wrote:
In article <jhachmann-A45404.23513616112006@news.giganews.com>,
johac <jhachmann@sbcglobal.com> wrote:
CAMBRIDGE, Mass. -- Countering the widespread view of evolution as a
process played out over the course of eons, evolutionary biologists have
shown that natural selection can turn on a dime -- within months -- as a
population's needs change. In a study of island lizards exposed to a new
predator, the scientists found that natural selection dramatically
changed direction over a very short time, within a single generation,
favoring first longer and then shorter hind legs.
If you think evolution can move fast for lizards there, check out my
home town.
http://news.yahoo.com/s/ap/20061117/ap_on_fe_st/alligator_motel_2
Damn things are so advanced here, they're staying in local hotels now.
{;-)
I can see some hotel/motel adds in the future. :-)
--
John Hachmann aa #1782
"Those who can make you believe absurdities can make you commit atrocities"
-Voltaire
Contact - Throw a .net over the .com
.
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| User: "Al Klein" |
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| Title: Re: Pressured by predators, lizards see rapid shift in natural selection |
17 Nov 2006 11:32:03 AM |
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On Thu, 16 Nov 2006 23:51:36 -0800, johac <jhachmann@sbcglobal.com>
wrote:
Natural selection can be studied experimentally and can work fast.
---
Pressured by predators, lizards see rapid shift in natural selection
And the fundies will say "but they're still lizards".
--
rukbat at optonline dot net
"If we really know Truth, we do not fear hearing falsehoods or half-truths; if we are not sure of the truth - we shudder and try to shout down every utterance." - A. J. Mims
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This signature was made by SigChanger.
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| User: "johac" |
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| Title: Re: Pressured by predators, lizards see rapid shift in natural selection |
18 Nov 2006 12:53:47 AM |
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In article <rfsrl21t5ct1f80t69d8rcp9affjhnm4kh@4ax.com>,
Al Klein <rukbat@pern.invalid> wrote:
On Thu, 16 Nov 2006 23:51:36 -0800, johac <jhachmann@sbcglobal.com>
wrote:
Natural selection can be studied experimentally and can work fast.
---
Pressured by predators, lizards see rapid shift in natural selection
And the fundies will say "but they're still lizards".
Of course. But then again the fundies would miss the point as they
always seem to do.
--
John Hachmann aa #1782
"Those who can make you believe absurdities can make you commit atrocities"
-Voltaire
Contact - Throw a .net over the .com
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