gradualist model and punctuated equilibrium model

[hiro]

do these 2 models show the evidence of evolution??
and what are the differences between these 2 models?

my eng is not good...i hope my questions won't make you confused...
thx

[mith]

Well both rely on the same evidence(fossils) so yes, they both support evolution.

The difference is mainly how they interpret gaps in the fossil record.

Punctuated equilibrium says that in long periods of time, mutations simply accumulate but do not cause any drastic phenotypical changes, followed by short periods where these mutations are suddenly expressed. This would account for the lack of transitional fossils in many phylogenic branches.

Gradualism is the model that says mutations and phenotypical changes are gradual and explain the fossil record gaps as simply missing because fossils are hard to find.

[hiro]

does it mean that Punctuated equilibrium is a modern explaination for evolution?
and why punctuated equilibrium is able to explain the sudden change for some species?

[mith]

Well it was posed later than the Gradualism model, but both are theories and there hasn't been any definite resolution yet.
Yes, punctuated is able to better explain sudden changes.

[hiro]

Well both rely on the same evidence(fossils) so yes, they both support evolution.

The difference is mainly how they interpret gaps in the fossil record.

Punctuated equilibrium says that in long periods of time, mutations simply accumulate but do not cause any drastic phenotypical changes, followed by short periods where these mutations are suddenly expressed. This would account for the lack of transitional fossils in many phylogenic branches.

Gradualism is the model that says mutations and phenotypical changes are gradual and explain the fossil record gaps as simply missing because fossils are hard to find.

sorry^^''' i do not really get it...you said mutations accumulate but not cause any drasic phenotypical changes... does it mean it cause drastic genetic changes?

[mith]

Well let's say for example you accumulated mutations like you accumulated parts for a sandwich. Everyday you go to the market and buy a few items, a head of lettuce, or maybe some ham. But until you have all the ingredients for your sandwich, it won't be made, the pieces will just lie around in your fridge. Same thing with DNA, a couple of mutations will probably cause some extra proteins to be made but until you have enough to chain them up into something big, you probably will not see any big changes.

[hiro]

Well let's say for example you accumulated mutations like you accumulated parts for a sandwich. Everyday you go to the market and buy a few items, a head of lettuce, or maybe some ham. But until you have all the ingredients for your sandwich, it won't be made, the pieces will just lie around in your fridge. Same thing with DNA, a couple of mutations will probably cause some extra proteins to be made but until you have enough to chain them up into something big, you probably will not see any big changes.

so..it's still have some changes but it's just a little not a drastic and it may not necessary change in phenotype but may be in some physical ..is it?

it's much better^^ thx

[mith]

Well the mutations happen no matter what.