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Author Topic:   Rate changes for evolution
PaulK
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Posts: 17822
Joined: 01-10-2003
Member Rating: 2.2


Message 31 of 40 (96692)
04-01-2004 5:23 PM
Reply to: Message 29 by mark24
04-01-2004 5:06 PM


Well how fast is "rapid" ? Eldredge and Gould were reacting to a fairly extreme gradualism which was apparently common amongst paleontologists at the time. If most evolution happens during relatively short intervals then it has to be rapid during those periods - in relative terms. Gould is fairly clear that he is talking of periods of centuries - perhaps a thousand years to get something different enough to be classified as a new species by paleontologists.
That's not fast in human terms. But it is the "rapid" evolution of PE.

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Replies to this message:
 Message 32 by mark24, posted 04-01-2004 5:37 PM PaulK has replied
 Message 39 by Brad McFall, posted 04-08-2004 6:27 PM PaulK has not replied

  
mark24
Member (Idle past 5196 days)
Posts: 3857
From: UK
Joined: 12-01-2001


Message 32 of 40 (96698)
04-01-2004 5:37 PM
Reply to: Message 31 by PaulK
04-01-2004 5:23 PM


PaulK,
Gould means by rapid up to 100ky-ish, according to The Structure of Evolutionary Theory. Enough to be potentially observed.
Mark
[This message has been edited by mark24, 04-01-2004]

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Replies to this message:
 Message 33 by PaulK, posted 04-01-2004 5:49 PM mark24 has replied
 Message 35 by Denesha, posted 04-02-2004 4:57 AM mark24 has not replied

  
PaulK
Member
Posts: 17822
Joined: 01-10-2003
Member Rating: 2.2


Message 33 of 40 (96704)
04-01-2004 5:49 PM
Reply to: Message 32 by mark24
04-01-2004 5:37 PM


Can you elaborate ? 100ky (i assume that's 100,000 years) for how much change ? If that's the time taken for speciation (even in the paleontological sense) it really doesn't sound like it's anything objectionable.

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 Message 32 by mark24, posted 04-01-2004 5:37 PM mark24 has replied

Replies to this message:
 Message 34 by mark24, posted 04-01-2004 6:46 PM PaulK has not replied
 Message 40 by Brad McFall, posted 04-12-2004 6:23 PM PaulK has not replied

  
mark24
Member (Idle past 5196 days)
Posts: 3857
From: UK
Joined: 12-01-2001


Message 34 of 40 (96725)
04-01-2004 6:46 PM
Reply to: Message 33 by PaulK
04-01-2004 5:49 PM


Hi Paul,
Can you elaborate ? 100ky (i assume that's 100,000 years) for how much change ? If that's the time taken for speciation (even in the paleontological sense) it really doesn't sound like it's anything objectionable.
It's the time for the evolutionary burst, rather than speciation itself. After that comes stasis. If I remember correctly it's only meant to be an upper limit ball park figure.
Mark

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Denesha
Inactive Member


Message 35 of 40 (96989)
04-02-2004 4:57 AM
Reply to: Message 32 by mark24
04-01-2004 5:37 PM


too short for fossils
Dear Mark24,
I think that 100Ky is too short for speciation based on fossils. This time is more likely a colonisation or secondary invasion time-duration.
Denesha

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Brad McFall
Member (Idle past 5033 days)
Posts: 3428
From: Ithaca,NY, USA
Joined: 12-20-2001


Message 36 of 40 (97034)
04-02-2004 11:33 AM
Reply to: Message 28 by Denesha
04-01-2004 2:43 PM


this is not rethorical.
Dont these conclusions rely on the notion of a past adaptation or anscestral form that is differnt from any view of taxonomy gleaned by only studying living kinds? Is not this a degree of subjectivity beyond that of any particular alpha taxonomic group becuase it involves a time interval and not just an origin in time short of the general concept of evolution itself??

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 Message 28 by Denesha, posted 04-01-2004 2:43 PM Denesha has replied

Replies to this message:
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Denesha
Inactive Member


Message 37 of 40 (97448)
04-03-2004 7:56 AM
Reply to: Message 36 by Brad McFall
04-02-2004 11:33 AM


Re: this is not rethorical.
Dear Brad,
I will say yes and no. We are limited in our investigation by the fact that we only have fossilized parts of past species.
Paleospecies are only known by that. This is true, unfortunately.
To take account of this subjetivity, it is assumed that mutations have always occured but have not changed the phenotype is most case.
Chronospecies are the best examples.
This inaccuracy is a parameter. A step ahead in objectivity?
Have a nice day,
Denesha

This message is a reply to:
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Brad McFall
Member (Idle past 5033 days)
Posts: 3428
From: Ithaca,NY, USA
Joined: 12-20-2001


Message 38 of 40 (97892)
04-05-2004 1:41 PM
Reply to: Message 37 by Denesha
04-03-2004 7:56 AM


As I read it Gould orginally used allopatry but it was ALL interms of speciation while he remains agnostic as to periparty,allopatry,polyplodiy. If I read him correctly he did not think that neobiology would invade the theoretical space he felt he opened for paleobiology by not needing to NAME the intermindable number of boundaries the resolution problem migh exascerbate. It is clear that as he thought Fisher's argument about species selection was "impotent" in the face of PE that he acknowdeges the differnt kinds of TIME I asked in question to you but still there is not way to COUNT objectively. My feeling like Gould has a "dominant stasis" feeling is that the form-making (including that preserved in rocks) can be better geometrized statistically such that conclusions that do not rely on his unsymmetrical relation of levels of selection can be arrived at. I have not done this as of yet. I hope this helps. I would perfer naming where Gould insists on statistical differences but that does not address the use of the distribution itslef which I think requires NOT using all of these DIFFERNT notions of time at the same stair step.

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Brad McFall
Member (Idle past 5033 days)
Posts: 3428
From: Ithaca,NY, USA
Joined: 12-20-2001


Message 39 of 40 (98762)
04-08-2004 6:27 PM
Reply to: Message 31 by PaulK
04-01-2004 5:23 PM


It is for reasons of this "time" that I am attempting to find the time in Einstein's notion of non-eucldian"time" else we have a plurivocity that remians unreduced and hence even if epistemologically one(I also doubt), it is ontologically divergent.

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Brad McFall
Member (Idle past 5033 days)
Posts: 3428
From: Ithaca,NY, USA
Joined: 12-20-2001


Message 40 of 40 (99492)
04-12-2004 6:23 PM
Reply to: Message 33 by PaulK
04-01-2004 5:49 PM


I would be satisfied if the branch-off was detailed with data of actual disruptive selection no matter the actual time(between natural and artifical selection under debate).

This message is a reply to:
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