punctuated equillibrium? (1 Viewer)

[mei_ling03]

please explain?
many thanks!

 

[Leap]

What syllabus point does that relate to?

 

[mei_ling03]

--> Describe the concept of punctuated equilibrium in evolution and how it differes from the gradual process proposed by Darwin.

 

[ballerinabarbie]

punctuated equilibrium suggests that species changed drastically over a short period of time, rather than evolving over many years... this is due to (usually) environmental changes...

it's in the heinemann text book

 

[swordfish]

instead of evolution occuring over a long time at a constant rate, punctuated equilibrium suggests that there was a series of periods of rapid evolutionary change ('rapid' in geological terms can mean hundreds of thousands of years)

 

[ballerinabarbie]

Originally posted by swordfish
instead of evolution occuring over a long time at a constant rate, punctuated equilibrium suggests that there was a series of periods of rapid evolutionary change ('rapid' in geological terms can mean hundreds of thousands of years)

that's probably in better "biological" terms than what i said! hahah

 

[mei_ling03]

cool thanks guys

 

[s2ophie]

If you can find it, there is a diagram that would help you explain it. There are two fork sort of graphs one looks like this sort of

|_|.....|
...|__ |
......|
(ignore the dots)
If that diagram makes any sense, that is puncutated eqilibrium.

The gradual process which Darwin suggested is baically the same diagram however using \ / instead of | usggesting a more gradual change process.


Does that make any sense?

 

[tempco]

Originally posted by s2ophie
|_|.....|
...|__ |
......|

Um... I don't seem to get it...
Anyway, I've learnt that punctuated equilibrium is caused by isolation? Can someone confirm this?

 

[crazylilmonkee]

in other words like this ^
instead of gradual slow changes.. there has been periods of stability and spurts of rapid evolution..

edit/ damnit doesnt work.,.., ignore

 

[tempco]

Oh right.. so the dots represent times of stability, and the lines represents change... so that graph thing is like a change/time graph, no?

 

[crazylilmonkee]

i tried to attach my pic but it wouldnt let me

 

[tempco]

What pic?

 

[crazylilmonkee]

graph

 

[~TeLEpAtHeTiC~]

here you go

As early as the 1940s biologists began to challenge the idea of gradualism. They pointed out that fossils of some species remain virtually unchanged over millions of years which conflicts with the concept of gradualism. Moreover, some organisms seem to appear out of nowhere in the fossil record, appearing suddenly and changing rapidly. In 1972 biologist E. Gould and N. Eldridge proposed the idea of punctuated equilibrium to explain these phenomenons. Punctuated equilibrium describes evolution as a process that occurs in bursts of rapid change that are followed by period with little or no change evolutionary wise. This is different from the gradual process proposed by Darwin which said organism undergoes a gradual change

i've deducted $5 from ur account mei.. many thanx..

 

[tempco]

Hrmm.. I'm still unsure about how it happens... isolation? or just coincedence?

 

[arls]

Originally posted by ~TeLEpAtHeTiC~
here you go

As early as the 1940s biologists began to challenge the idea of gradualism. They pointed out that fossils of some species remain virtually unchanged over millions of years which conflicts with the concept of gradualism. Moreover, some organisms seem to appear out of nowhere in the fossil record, appearing suddenly and changing rapidly. In 1972 biologist E. Gould and N. Eldridge proposed the idea of punctuated equilibrium to explain these phenomenons. Punctuated equilibrium describes evolution as a process that occurs in bursts of rapid change that are followed by period with little or no change evolutionary wise. This is different from the gradual process proposed by Darwin which said organism undergoes a gradual change

i've deducted $5 from ur account mei.. many thanx..

well stated! good definition tele.... thats going straight my exam paper!!

 

[~TeLEpAtHeTiC~]

Originally posted by NekkidSerpent
Hrmm.. I'm still unsure about how it happens... isolation? or just coincedence?

there are several mechanisms that cause punctuated equilibrium but no its not isolation, punctuated evolution remember refers to quick sporatic changes followed by long periods of nothing..
evidence to show punctuated equilibrium are inconsistencies in fossil records where fossils suddenly transgress into new species and change rapidly (in geological time) however remain the same for millions of years

 

[tempco]

"Punctuated equilibrium, on the other hand, proposes that speciation occurs as a splitting of lineages. Reproductive isolation begins with physical isolation of a small sub-population, and the small size of the isolated population renders it relatively unstable evolutionarially. The conditions that allow stasis to occur are reversed, and evolution in the isolated population occurs at a very fast rate until the conditions for stasis are met again."

Taken from http://www.geocities.com/CapeCanaveral/Lab/1366/pe.html#mechanism". Isolation seems to be one of the causes... happy I got that out of the way... was eating the back of my mind!

 

[arls]

so..... conflicting accounts on isolation? now im confused!
whos right tele or nek?