[meteorite-list] Impact extinction events accelerate evolution?

From: Mr EMan <mstreman53_at_meteoritecentral.com>
Date: Mon, 3 Nov 2008 15:56:14 -0800 (PST)
Message-ID: <601347.29876.qm_at_web55204.mail.re4.yahoo.com>

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 Mon 03 Nov 2008 06:56:14 PM PST