• Quick note - the problem with Youtube videos not embedding on the forum appears to have been fixed, thanks to ZiprHead. If you do still see problems let me know.

Evolution: the Facts.

I'm curious, h.g.Whiz: what exactly is wrong with that statement? While some organisms clearly have evolved to use and obtain energy more efficiently, others clearly have not. Mayfly adults don't even have mouths--they have just enough time to mate, then they die. Sponges, corals, in fact a huge number of ocean animals (all the benthic sessile ones) clearly aren't after maximizing energy input. The only unifying theme of evolution I can see is that things that have more offspring that survive tend to dominate the population next generation.
 
h.g.Whiz said:
jimbob said:
Evolution is not a progression towards anything except reproductive success.
Click to expand...

Acquiring energy is pretty important.


"Surveying the long chequered, but on the whole continuous,
ascent of man from primeval conditions to the
summit of his present-day powers, what has it all been at
bottom but a fight with Nature for energy for that
ordinary physical energy of which we have said so much ?
Physical science sums up accurately in that one generalisation
the most fundamental aspect of life in the sense
already defined.
Of course life depends also on a continual supply of
matter as well as on a continual supply of energy, but
the struggle for physical energy is probably the more
fundamental and general aspect of existence in all its
forms. The same matter, the same chemical elements,
serve the purposes of life over and over again, but the
supply of fresh energy must be continuous. By the law
of the availability of energy, which, whether universal
or not, applies universally within our own experience,
the transformations of energy which occur in Nature
are invariably in the one direction, the more available
forms passing into the waste and useless unavailable
kind, and this process, so far as we yet know, is never
reversed. The same energy is available but once. The
struggle for existence is at the bottom a continuous
struggle for fresh physical energy"

FREDERICK SODDY
Click to expand...

h.g.Whiz said:
jimbob said:
Evolution is not a progression towards anything except reproductive success.
Click to expand...
:redface1
Your not going to tolerate any evolving while on your watch. Are you?:cry1
Click to expand...

You seem to be confusing the cause and the effect.

The cause is evolution towards reproductive success, the effect is how this is achieved.

The camel evolved its hump because proto camels with proto-humps had more offspring that managed to reproduce.

The female giant octopus lays its eggs and tends them until her death because proto-octopodes that exhibited such behaviour had more reproducing offspring than those that didn't.

Pedantically, I don't like the phrase "evolved to" as that implies direction. Mammals didn't evolve to suckle their young. Mammals evolved the suckling of young because it improved their reproductive success.

It is a subtle distinction.

EDIT:

"Acquiring energy" is just a restatement of the fact that organisms need to respire
 
Last edited:
jimbob said:
You seem to be confusing the cause and the effect.

The cause is evolution towards reproductive success, the effect is how this is achieved.

The camel evolved its hump because proto camels with proto-humps had more offspring that managed to reproduce.

The female giant octopus lays its eggs and tends them until her death because proto-octopodes that exhibited such behaviour had more reproducing offspring than those that didn't.

Pedantically, I don't like the phrase "evolved to" as that implies direction. Mammals didn't evolve to suckle their young. Mammals evolved the suckling of young because it improved their reproductive success.

It is a subtle distinction.

EDIT:

"Acquiring energy" is just a restatement of the fact that organisms need to respire
Click to expand...

Confirmed. That was bloody pleasant.

:thanks
 
The concept of "ring species" folds nicely into explaining the concept of punctuated equilibrium.
 
The problem is, it folds nicely into phyletic gradualism as well. The same process can yeild both results, as PE and PG (Phyletic Gradualism) are long-term tempos, rather than short-term events. So ring species don't tell us much about whether PE or PG dominates.
 
Isn't PE just an observed product of environmental change rather than inherent gene fluctuation? As in the PE observed in the fossil record corresponds to environmental changes in the fossil record and that's why it "seems" punctuated rather than gradual?

I never got to see Gould address that, though I am sure he has at one point...
 
Well, Gould is no longer the ultimate authority on PE--the theory has been taken up by others, even prior to his death.

To be honest, as far as I'm aware we don't know why we see PE instead of PG. In part, yeah, it could be environmental--things stabilize until some major purturbation occurres. But that doesn't explain stability during major purturbations (ice ages and the like), and it certainly doesn't address the issue of scale (at the largest scale, evolution certainly exibits PE-style evolution, but it's not clear why). It also doesn't explain why some critters show PE evolution, and some (oddly enough, the ones we have the best fossil records for--the microfossils--though I hasten to add that this does not mean that if we find more of the other fossils they'll show PG evolution, but rather it's simply an odd correlation) tend to show PG.

The other thing to remember is that the environment is not stable. Ever. Plants and animals constitute part of the environment, and even in equilibrium phases of PE there's a lot of evolving going on (background radiation and extinction rates). The concept of a stable environment over geologic time is a myth. So the issue becomes HOW MUCH change causes punctuation in PE. And it doesn't even have to be directly related to the organisms in question--any lessening of pressure will do it.
 
Well you have to remember that evolution works via natural selection. Perhaps microorganisms are fit for larger environmental changes already; ie they don't work to fill new niches and larger organisms do. Plants are probably an exception.

I always remember the deep sea creatures like the nautilii (I think that's the plural) who show very little morphological change throughout the fossil record to now, size being the most obvious. Their environment doesn't change enough for there to be a new selection pressure.

That's my thoughts on it.
 
Actually, the sea is where we learn the most about evolution. There's an idea that ecosystems evolve in the shallow sea, then migrate to the deeper parts of the ocean as new ecosystems arise. Not sure what I think of it, other than that I don't see any real mechanism for it.

The other thing to remember is that living fossils represent one branch of a long, bushy tree. The nautilii are cousins to the ammonites, which were incredibly diverse (they're used as index fossils). Crocs are only the surviving members of the Crocodilians, a group that was extremely diverse.

But you raise a valid point: simple organisms are often best-adapted for their environments. A bacteria, which can use most chemicals it finds, is better adapted than a lion, which requires specific other organisms to survive. Such organisms could relatively easily weather most purturbations, and that's probably why we see PG, which is more random than PE.
 
Well I would have thought the nautilii which ARE diverse are diverse because of they stay within their environment (and the ones that migrate tend to stay at where they migrated to) so that you have stasis of a particular deep sea nautilii for a LONG period of time with little change, because its environment doesn't change. I would imagine the deep sea to have very little niche diversity, which means there's lower pressure, which means PE is more difficult to observe, or so the logic says to me anyways.

I know there's diversity in Nautilii though, my fossils show me that =D
 
The problem is, the deep sea has STRONG selection preasures, particularly concerning food and, well, preasure. Food is scarce in the deep sea, and things that can't handle that don't live. You can get around this by having a very slow metabolism, or by "island hopping" from dead carcass to dead carcass (or deep-sea vent to vent, or both), but you have to get around it somehow. And the preasure is obvious--if you can't handle it, you simply die outright.

If anything, I'd say this high selection preasure is responsible for stasis in the organisms that experience it. Without such a high selection preasure you'd see more genetic drift. As it is, it's take a pretty rare combination of events to make any adaptation significantly better than what's already there, and still not kill the organism.

Gould said something similar: he viewed natural selection as largely a limiting or stabilizing force, and it only operated to increase diversity during the punctuations in PE. This is one of the areas I question PE, to be honest--I'm not sure we know enough about paleoecology, and particularly long-term paleoecology, to make those statements. Sepkoski's Curve indicates that we really don't have a good sense of what lived where and when (or at least, it does when you look at all of the issues involved in it), and I've yet to see any good indications that individual time periods are much better.
 
No I get that there is a strong selection pressure in that the environment is extreme, but the environment isn't really CHANGING at a rate we notice (ignoring current climate change...)

They are, for the moment, adapted to their environment in the deep sea. If that environment doesn't change, and I suggest that if it has changed (geologically) recently then there are no new pressures to select for a change in which PE should be observed.

That is if we assume that PE SHOULD be observed in a moment of niche/environmental change, when new gene fluctuated should be at its most rapid. This doesn't account for sexual selection pressures, but that's another discussion that I cannot illustrate easily with PE.
 
Last edited:
The environment is changing all the time.

We might not notice it because we can't see many parasites, but they have a major effect on evolution of physiological responses that affect the success of parasites and other pathogens within the body.
 
Dinwar said:
...The Mojave Green rattlesnake experienced a mutation about 20 years ago. It was always a nasty little serpent, but it become even nastier--20 years ago, it gained a new toxin in its venom. I forget which came first, but it now has both a neurotoxin and a hemotoxin. Because apparently shutting down one major organ system isn't enough when you eat rodents. Anyway, the thing is, they're still the same species. A Mojave Green is a Mojave Green, whether it's 1920 or 2010. So evolution, even of weapons, can happen outside of speciation. ...
Click to expand...
That was new to me! Thanks for posting that up.



steenkh said:
You mean like the Northwest Pacific Tree Octopus?
;)
Click to expand...

Thanks for posting up this great link. I'll put it to good use ;)
 
Patrick1000 said:
I thought it to be a progression away from Republicanism....
Click to expand...

Not even that; as I mentioned above, parasites are a major selective force. They are locked in an arms race with their hosts so are highly evolved...
 
Last edited:
You must log in or register to reply here.

Back
Top Bottom