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Author | Topic: Punctuated Equilibria: The Basics | |||||||||||||||||||||||||||||||||||||||||||
Taq Member Posts: 10084 Joined: Member Rating: 5.1
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CRR writes: The PE model was developed to explain large morphological gaps in the fossil record, saltations. quote: PE explains gaps between species in the fossil record, but it doesn't use saltation to explain it. A gap in the fossil record is a gap in the fossil record, not a gap in the actual evolutionary history of the species.
If you think you can see a fossil series showing many small steps then punk eek does not apply to that example. That would also be false. Gould and Eldredge pointed to several instances where there was rapid evolution in the fossil record, complete with transitional fossils between species:
quote: They were able to find positive evidence of allopatric speciation with transitional fossils between species, and then evidence of that new species replacing the less derived parent population. Edited by Taq, : No reason given. Edited by Taq, : No reason given. Edited by Taq, : No reason given.
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Taq Member Posts: 10084 Joined: Member Rating: 5.1 |
CRR writes: More correctly I should have said "The PE model was developed to explain large morphological gaps in the fossil record, seeming saltations. That is false. PE was used to explain rapid evolution between species, followed by longer periods of stasis. The gap between species is not a large morphological gap.
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Taq Member Posts: 10084 Joined: Member Rating: 5.1
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CRR writes: The idea of Punk Eek is that the evolution takes place "off stage" where it isn't recorded in the fossil record . . . Gould and Eldredge cited two examples of PE being recorded in the fossil record: "PE sometimes is claimed to be a theory resting upon the lack of evidence rather than upon evidence. This is a curious, but false claim, since Eldredge and Gould spent a significant portion of their original work examining two separate lines of evidence (one involving pulmonate gastropods, the other one involving Phacopsid trilobites) demonstrating the issues behind PE (1972). Similarly, discussion of actual paleontological evidence consumes a significant proportion of pages in Gould and Eldredge 1977. This also answers those who claimed that E&G said that PE was unverifiable."Punctuated Equilibria The gap between species is not a large morphological gaps. On top of that, Gould has stated that there are plenty of transitional fossils filling those gaps: "Since we proposed punctuated equilibria to explain trends, it is infuriating to be quoted again and again by creationistswhether through design or stupidity, I do not knowas admitting that the fossil record includes no transitional forms. Transitional forms are generally lacking at the species level, but they are abundant between larger groups."--Stephen Jay Gould, "Evolution as Fact and Theory"
The evolution that takes place "off stage" is assumed to follow normal Darwinian processes. That is false. The observation of a nested hierarchy demonstrates that the processes were Darwinian. It isn't assumed.
Note that evolution can potentially take place more quickly in a small population because the average time for a change to reach fixity is correspondingly smaller. On the other hand the smaller population has less chance of producing a favourable mutation. Selection is often stronger at the edges of a species range meaning that mutations which are only slightly beneficial in the center of the species range can be much more strongly beneficial at the edges of the range. There is also the possibility that a neutral or even slightly deleterious mutation in the main population can be beneficial at the edges of the species range. Therefore, the subpopulation may already have the beneficial mutations it needs in low numbers.
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Taq Member Posts: 10084 Joined: Member Rating: 5.1 |
CRR writes: Or in other words evolution takes place "off stage" where it isn't recorded in the fossil record so that when it later reappears there is a large change, an apparent saltation. The evolution that takes place "off stage" is assumed to follow normal Darwinian processes. They also cited instances where rapid peripatric speciation was recorded in the fossil record. Also, it isn't assumed to be a Darwinian process. We observe that the end result is a nested hierarchy which is evidence that it was a Darwinian process.
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Taq Member Posts: 10084 Joined: Member Rating: 5.1
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Dredge writes: Athesits try and explain all those inconvenient gaps with their hypothetical (ie, imaginary) PE. Gould and Eldredge pointed to several places in the fossil record where PE was captured without gaps. Perhaps you should read the actual paper: http://www.sciacchitano.it/...d%20puctuated%20equilibria.pdf Start at the bottom of pg. 99. They were able to show an evolving population of snails with intermediates that evolved in one place. As other species of snail died out in other regions the evolving snail species from one region moved in and took over those territories. The fossil record in these areas showed an abrupt change in species, but this due to migration of the species that evolved in a different region. PE isn't imaginary. It is very real.
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Taq Member Posts: 10084 Joined: Member Rating: 5.1 |
Dredge writes: PE is magic masquerading as science. Denial ain't just a river in Egypt.
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Taq Member Posts: 10084 Joined: Member Rating: 5.1 |
Faith writes: Welcome back dredgie. I agree that PE is magic masquerading as science. Can you explain how a snail species migrating to a new area is magic?
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Taq Member Posts: 10084 Joined: Member Rating: 5.1
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Faith writes: The snail species didn't migrate anywhere, it got killed and buried by the Flood and stayed right where we find it in the strata. It's funny that you accuse me of believing in magic simply because I propose migration as a mechanism for a species to move around. You then turn around and propose a magical flood, all without any self awareness of sense of irony. I don't know if I should laugh or what.
And so did all the other species of snail in other parts of the strata, same as for every species of everything else too. Movement is purely an imaginative or magical idea. So I guess people are just making stuff up when they talk about this invasive mussel species that is quickly invading Minnesota: Zebra mussel (Dreissena polymorpha) | Minnesota DNR If you live out in the Great Basin the western US you already know about cheat grass which is an invasive plant species that moved here in the last 200 years. Oh, and let's not forget about the invasive python species that just migrated to Florida. Yeah, this is all magic and it never happens without a global flood.
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Taq Member Posts: 10084 Joined: Member Rating: 5.1 |
Faith writes: Of course there are migrations, I said nothing about that, what I said was that it's ridiculous to think you can tell such things from the fossil record. Why is it ridiculous?
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Taq Member Posts: 10084 Joined: Member Rating: 5.1
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Dredge writes: Really? So Gould and Eldredge invented PE to explain gaps within a species? My understanding is they invented it to explain all those gaps in the fossil record. Gould and Eldredge explained why evolutionary mechanisms will produce gaps in the fossil record, and the mechanisms they described are active within species. For example, if a subpopulation of a species is at the edge of its range it will experience different and more severe selection than the population found in the middle of the species' range. This causes higher rates of change in small subpopulations at the edge of a range. This faster evolving subpopulation can then replace the larger population suddenly, and if you look at the majority of the fossil record you will see a sudden replacement. All of this is change within a species. Edited by Taq, : No reason given.
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