Help me out here guys.

[Baggins]

Posted by Baggins:

"I think it would be self evident to most palaeontologists that there is no one evolutionary mechanism shown in the record."

Ok, I think we have identified our disconnect. I do not recall stating that there was only one evolutionary mechanism, or that PE was the only one. Simply that PE seemed to be the favored one. As previously stated, I had diagrams to illustrate what I was discussing, but couldn't put them up. In this case I think may have helped.

Favoured in what way?

If you study different animals you will see different evolutionary mechanisms. I don't see why PE should be favoured over gradualism or vice versa, they both obviously happen.

Gradualism occurs when animals live in stable environments, PE seems to be a reaction to environmental stress.

I doubt you would find any palaeontologist who would deny they both occur, but you would find lots who would claim that their research showed that heir favoured mechanism was very important as the constant spats that Gould had with other palaeontologists shows.

Look, no-one can be an expert in every field. As Chalron alluded to, one needs to specalize, particularly by the time they reach graduate school. So no, although I do know what foraminifers are, I do not know all about globigerinoides. But like you, I do know how to read. And besides, without looking, what is the difference between a lacI and a lacZ?

I've no idea, I may as well ask you to state the major differences between kirchoff migration and finite difference migration, utterly pointless.

What I am trying to point out is that gradualism happens and it isn't a subordinate evolutionary mechanism to PE, it depends what type of animal you study. If you study large, complex exciting animals then PE may seem to be the dominant mechanism.

But don't forget the guys studying small boring animals in stable environments with fast turn over of generations, they have data too and it is equally as valid.

 

[Tomk80]

I have pointed this out earlier, but it seems from the present discussion that PE and gradualism are used as a different mechanism. This is not correct, it is the same mechaism, but the location where it happens and the size of the population in which it happens is different.

PE: isolated location, small population.
Gradualism: change happening in large population over a large location.

Same mechanism, people.

 

[sfs]

Posted by sfs:

"also don't understand the physical model (and probably won't, since there doesn't seem to be a published paper associated with this hypothesis)."

I don't think there is one. This was something which occurred to me one night while studying mutation rates of e coli, and simply out of interest I kicked it around in my spare time.

Unless you noticed the correlation between the galactic wanderings of the solar system and mass extinctions independently, I don't mean your model. I mean the model proposed by Medvedev and the other guy for why radiation should increase as the solar system heads above the galactic plane. They may have a reasonable model, but I can't tell from news reports and the basic physics doesn't look like it makes a lot of sense.