[meteorite-list] Impact extinction events accelerate evolution?

From: Steve Dunklee <sdunklee72520_at_meteoritecentral.com>
Date: Tue, 4 Nov 2008 07:57:20 -0800 (PST)
Message-ID: <987260.1921.qm_at_web33207.mail.mud.yahoo.com>

I find it amazing meteorites are relativly rare , yet played such a critical role in our evolution by knocking out the competition. Your respopnse was pretty much what I was thinking myself, and as always well stated.
   When I look at the impact extinction layers at the quarry where I work, and see all the thousands of layers magnetite and other materials .I wonder if it actually represents millions of years from the end of limestone growth from one era to the beginning of growth in the next. If there were any fossil dna present in each layer with common specie. the amount of time from the end of one to the beginning of the next could be determined using the standard accepted mutation rates.
    Dou you know of any amber from the different layers? and have any remnant DNA ever been found in it?

Steve


--- On Mon, 11/3/08, Mr EMan <mstreman53 at yahoo.com> wrote:

> From: Mr EMan <mstreman53 at yahoo.com>
> Subject: Re: [meteorite-list] Impact extinction events accelerate evolution?
> To: meteorite-list at meteoritecentral.com, sdunklee72520 at yahoo.com
> Date: Monday, November 3, 2008, 5:56 PM
> Good question Steve,
> I favor the rate remaining the same scenario. The
> experiments you suggest have effectively been done that
> enrich the given mutations in white mice and bacteria
> strains. Only most forced mutation experiments kill off a
> whole lot of test subjects and take human lifetimes to
> enrich mutations into a bloodline but usually are designed
> to develop a flaw vs an advantage. (I think we now have
> strains of cannibal barking cockroaches that can live in
> high methane,low-light-high pressure atmospheres and inside
> reactor vessels. They aren't good for anything but you
> can't kill'em off. I believe these may have come
> from attorney/politian donors--but I digress)
>
> As to changing mutation rates and in talking about Cambrian
> and later extinction events, IMO there is no suggestion that
> there is an increased mutation"rate" per se,
> caused by the extinction event. Extinction events are
> rooted in multiple causes and only a few of them offer DNA
> damage potential such as an abnormal sustained gamma ray
> burst over 1000's of generations or increased
> ultraviolet energy reaching habitats.
>
> The mutation "rate" would seem to be constant
> even when evolution of new species is expanding (S. Jay.
> Gould spoke of punctuated evolution but this supports niche
> exploitation vs accelerated mutation). For a time after the
> extinction event,the criticality/consequence of a particular
> neutral or negative mutation isn't so heavily
> challenged. With competition reduced to nill, more mutations
> will be passed along that have no consequence for the time
> being. As more species fill the niches the apparent rate of
> evolution, as measured in new species,slows.
>
> The jump in radiation of species post event--acceleration
> of evolution into vacant eco-niches, is more likely owing to
> the absense of competition pressures from the former niche
> holders. This results in an ecosystem with a more
> forgiving, less-consequential challenge for the mutated
> bloodline. (e.g. having ample food and habitat without the
> pressure of also having to overcome another creature's
> advancing mutations, avoiding predators,etc. Simply, when
> food is ample, most any mouth part will work to scrap it
> up).
>
> Elton
>
> --- On Fri, 10/31/08, Steve Dunklee
> <sdunklee72520 at yahoo.com> wrote:
>
> > From: Steve Dunklee <sdunklee72520 at yahoo.com>
> > Subject: [meteorite-list] Impact extinction events
> accelerate evolution?
> > Was it the repeated impact events in the primordial
> soup
> > that caused the chemical changes that sparked the
> creation
> > of life on earth?
> > Current science shows that environmental factors
> cause
> > mutations in DNA. Instead of being detrimental to life
> and
> > genetic diversity. Might the repeated impact
> extinction
> > events ,actually caused an increase in genetic
> mutations? Or
> > do the mutation rates remain the same?
> > Have there been any studies done where the
> conditions
> > after an extinction event have been recreated over
> several
> > generations ,to see if there is an increase in
> mutations
> > over a control group in small mammals?This would
> probably
> > require subjecting a group of mice to cold
> conditions,with a
> > near starvation diet in the dark for several years.and
> > comparing the mutation rate to a control group. and
> also
> > having a group exposed to high temperatures, a
> starvation
> > diet and high lighting and low light for comparison of
> > genetic mutation rates.
> > There may already be such studies out there
> somewhere.
> > If any list member have any links or further
> information to
> > them ,this troll would appreciate it!
> >
> > Have a great day
> >
> > Steve


      
Received on Tue 04 Nov 2008 10:57:20 AM PST