Polypterids and Punctuated Equilibrium

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deep in some amazonian under water river cave lives the beast of the south american polypetids.
 
I didn't say it was a joke. Like I said, lungfish, which are similar to polys occur in both, too ;)
 
DariusAmurdarja said:
question is, why went polypterids extinct globally but not in africa?
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Considering how versatile the polypterids are, I would guess that it is possible that their native range dried out. Even the hardiest fish can't live without water, as I found out when my 18" Ornatipinnus jumped out of the tank and made it 20 feet across the living room floor before it died. That's a guess, I'm no paleontologist.
 
I personally view evolution as a combination of phyletic gradualism and puntuated equilibrium. The periods of stasis mentioned by OP could very well be periods in which PG is the dominant form of change. Though major events such as the permian extinction would open large niches in the so called "food chain" and allow for certain mutations to be more readily useful in adaptation than previous times, enabling PE.

It is important to note however, that the observation of a single species does not, and in fact cannot, be used as "proof" of a theory. There was a paper posted here a while ago, I'm not sure when, that compared the evolution of gars (lepisosteiformes) and polypteriformes, I'm not sure what the actual content of the paper covered but I have it on my laptop, I'll be able to look it over later and if it turn out there's interest in it I may be able to post it later tonight.

In any case the small amount of change in polys is surely indicative of their ability to adapt to their surroundings, and a testament to their ability to compete with other species. It's an interesting point you raised and I'm looking forward to reading more of this discussion.
 
Llamalord said:
I personally view evolution as a combination of phyletic gradualism and puntuated equilibrium. The periods of stasis mentioned by OP could very well be periods in which PG is the dominant form of change. Though major events such as the permian extinction would open large niches in the so called "food chain" and allow for certain mutations to be more readily useful in adaptation than previous times, enabling PE.

It is important to note however, that the observation of a single species does not, and in fact cannot, be used as "proof" of a theory. There was a paper posted here a while ago, I'm not sure when, that compared the evolution of gars (lepisosteiformes) and polypteriformes, I'm not sure what the actual content of the paper covered but I have it on my laptop, I'll be able to look it over later and if it turn out there's interest in it I may be able to post it later tonight.

In any case the small amount of change in polys is surely indicative of their ability to adapt to their surroundings, and a testament to their ability to compete with other species. It's an interesting point you raised and I'm looking forward to reading more of this discussion.
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This is exactly the position that I take, although I am certainly not qualified to have a scientific opinion. It makes logical sense that a species can change over time slowly to very gradually improve itself, or it can change rapidly (in evolutionary terms) in order to survive in a rapidly changing environment. A generalized species may not need to change even in a rapidly changing environment, or in a gradually changing environment. Some environments do not change much over long periods of time. This provides that stasis, gradual change, and rapid change can all occur depending on need and whether or not the species survives.
 
Great post!!! What prompted this?? BTW Nice collection. Did you guys touch on Pangea? I mean was it North or South America conected to West Coast of Africa??? How bout The North American Bowfin??? I know it is not ploypteridae but pheno type has alot in common with bichirs.
 
yama said:
How bout The North American Bowfin??? I know it is not ploypteridae but pheno type has alot in common with bichirs.
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You're correct in the sense that bowfins are not a member of the polypteridae family, however, you should be careful to link animal of similar phenotypes. While it may serve to demonstrate a closeness between the two species, other factors such as convergent evolution make morphological classification a very shady way to demonstrate the closeness of such species. The difference between 2 and 3 toed sloths comes to mind, or the bat which had once been classified as a bird. That said the bowfin and polypteridae families are somewhat similar in that they are both ancient ray-finned fishes, among other similarities. The separation of Pangea also likely played a role in each's current geographical distribution, as well as subsequent geological events.
 
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