NationStates Jolt Archive

For you that don't know what this means here (http://necsi.org/projects/evolution/evolution/grad+punct/evolution_grad+punct.html)is a rather simple, and comprehensive guide to it.

I suppose a larger portion of people go along the lines of Darwinism and prefer gradualism. However, I tend to go down the path of P.E. I choose this line of thinking mainly because if you look through out history, sure you may see how in some millions of years a bird species may evolve to better adapt to a climate and what not, but I believe if you look at fossil records you can see periods where mass extinctions happen due to climate changes and all that, and not too long after that, a great load of new species just appear, fully equipped to survive, as if they some how "sponataneuosly appeared":p. Anyways, i think we can tell from those type of events that much of evolution hasn't occured through slow gradual time periods, but rather after catastrophic events, with mass extinction.

So which school of evolution do you follow, and why?

BTW sorry if i left out any other schools of evolution. If you beleive another way of evolution, please enlighten me.

Both, of course. Evoution is gradual among species nearly totally suitable to their environment. It's when an environment rapidly becomes unsuitable that evolution kicks it into high gear.

Both, of course. Evoution is gradual among species nearly totally suitable to their environment. It's when an environment rapidly becomes unsuitable that evolution kicks it into high gear.

Blasted! I meant to make a both option too. Oh well. I suppose "other" will work for that. I suck at making polls.:(

Both, of course. Evoution is gradual among species nearly totally suitable to their environment. It's when an environment rapidly becomes unsuitable that evolution kicks it into high gear.

Gotta agree with this.

but I add another time when evolution kicks up. Radial evolution, as could be seen in New World monkeys...probably one old world species made it to South America, and rapidly evolved into many species to fill many different niches.

It easily explains why many of the NWM have prehensile tails.


it has also been shown that evolution occurs much faster near the equator. I forget why, but it does. *nod*

Gotta agree with this.

but I add another time when evolution kicks up. Radial evolution, as could be seen in New World monkeys...probably one old world species made it to South America, and rapidly evolved into many species to fill many different niches.

It easily explains why many of the NWM have prehensile tails.


it has also been shown that evolution occurs much faster near the equator. I forget why, but it does. *nod*

Orly? At the equator? I'll ask my professor about that tommorrow :)

Had to pick other on this. Punctuated equilibrium, despite Gould's claims to the contrary, isn't really a challenge to the Neo-Darwinian synthesis. No one actually believes that everything is constantly under selection pressures, instead things are usually at the top of their fitness landscape until pressures change. Dennet's Darwin's Dangerous Idea has a good overview of this stuff.

Orly? At the equator? I'll ask my professor about that tommorrow :)

I'll see if I can find the article...it might only be available on my BU account...


EDIT:
the actual research paper is only on my BU account, but I found this (http://www.eurekalert.org/pub_releases/2006-05/uof-tet053106.php) about it

*peaks in thread*
*gets confused*
*leaves thread and goes back to editing photos*
*scratches arm*

*peaks in thread*
*gets confused*
*leaves thread and goes back to editing photos*
*scratches arm*

Hurry up and evolve already, or do i have to send an asteroid to philly to help you out? :p

Hurry up and evolve already, or do i have to send an asteroid to philly to help you out? :p

...:eek:

Well.. if it got me another day off from school, while keeping the internet and tv working, sure, why not?

Both.

I find it baffling that you think it has to be one or the other. Particularly when the article says both happen.

Both, of course. Evoution is gradual among species nearly totally suitable to their environment. It's when an environment rapidly becomes unsuitable that evolution kicks it into high gear.

Well, that can be explained in a number of different ways.

Explanation 1:

A rapid decrease in competition from other sources would leave an over abundance, for a time, for other species, and as there would be less competition, many species could function in the same environment, using the same resources, for at least a short period of time. This would allow rapid evolution, as many traits could arise among members of the same parent group, and several off shoots would be allowed to occur, with no specific genetic group gaining a substantial advantage over the other, at least for a time, as resources would be plentiful. Since there is less competition, gradual evolution can occur more rapidly, as groups need not compete, with certain lines dying off or becoming less frequent. See the extinction of the dinosaurs and the rapid influx of mammilian species.

Explanation 2:

When looking at why certain animals evolve more rapidly than others, one must not looking at overall time span, but generation length. The reason why smaller animals, or animals with shorter generation lengths, evolve more rapidly is because it takes less time for genetic variants of a group to occur, as the time for the parent groups to pass on thier information to the next is greatly reduced. This creates a much more rapid changes seen in these animals than in others. It can appear that the changes are sporatic, but that is largely because A)It is almost impossible to find a direct fossil line, and due to rapid changes, if you find a species from one age period, and a species you would assume to be an ancestor from another, not to much earlier, period, there can drastic difference due to fast, but gradual, evolution

And I have other ideas, but it's late, and I want to go to bed. However, from what I have read, it appears that PE is more Lemarkian, which has many flaws, which I will get into later.

Both.

Species very slowly change little by little over time if nothing particularly exciting is happening.

When some sort of cataclysm happens, though, you see evolution go much faster, due to massive environmental changes.

Afterward, things go back to gradual change.

Both, of course. Evoution is gradual among species nearly totally suitable to their environment. It's when an environment rapidly becomes unsuitable that evolution kicks it into high gear.

Indeed. After all, life has existed on this planet for several billion years. It knows when to do whatever it takes to keep itself around.

Both.

Species very slowly change little by little over time if nothing particularly exciting is happening.

When some sort of cataclysm happens, though, you see evolution go much faster, due to massive environmental changes.

Afterward, things go back to gradual change.

I'm not bought on the idea of PE. It requires spontaneous mutations to happen, however this is not observed(As far as I know). For example, let's go like this:

Parent Individual
Contemporary Individual.

Now, any significant mutations cannot occur in the lifespan(post-birth) of the Parent Individual, as it would require the recoding the genetics of all cells of the individual in order to be a true mutation. This does not happen, as cells are not bound together after birth. Mutations might occur, causing local changes in a group of cells, however it would not occur in the organism as a whole. This would mean that the organisms reproductive cells would have very little chance of having mutated genetic strands, except on the off chance of mutated reproductive cells genetics, as that is really the only important part of the body when regarding reproduction(For instance, if one were to have a mutation in genetics in the cells in an area of the skin which may or may not give a better chance of survival to the individual in one's lifespan, it would not affect the genetics of the reproductive cells, thus that trait would not be passed on). Thus, the mutated trait of the Parent Individual does not pass on to the Contemporary Individual, as the genetics of the reproductive cells would be more or less independent of those of the mutated skin cells.

Now, it is possible, I suppose, for mutations to occur at a pre-embryonic stage, which would allow for all of the cells of a particular individual to have a different genetic make-up than it would normally have if the mutation were to happen, however, it is doubtful as to whether this would cause PE, as the traits that would arise would be unknown as to whether it would be helpful, harmful, or neutral. This would mean that there would be no actual increase in likely hood of reproduction of the individual to the environment, as the trait likely would not have any affect at all on the reproductive sucess of the individual pertaining to the environment. It would because of this that PE would actually cause evolution to be slower than gradualism, as the mutation would occur at chance, and there are far more environmentally neutral or harmful traits than there are helpful ones.

Of course, this is talking of multicellur organisms, as I have very little knowledge of single-cell evolution or biology.

Cataclysms(such as mass extinction) only cause an increase of resources, due to less competition. This means that many lines of a certain animal can evolve quickly, and live in the same environment, albeit for a relatively short period of time, because as populations grow, the resources become more and more scarce, causing more and more competition, which causes those lines which are not as suitable as others(in terms of competition of resources) to die out, which in turn slows evolution.

Basically, competition of resources is teh reason for evolution, however an abundance of resources allows greater evolution. A strange idea, for sure.

And to address this part from the article:

"The idea of punctuated equilibrium originated long after the idea of gradualism. Darwin saw evolution as being "steady, slow, and continuous". Later, scientists were studying fossils and they found that some species have their evolution almost "mapped out" in fossils. For others they found a few, very different species along the evolutionary course, but very few or no fossils of "in between" organisms. Also, when dating the fossils, scientists saw that in some species change was very slow, but in others, it must have occurred rapidly to be able to produce such change over such a short amount of time. The scientists reasoned that there had to be another way that evolution could have happened that was quicker and had fewer intermediate species, so the idea of punctuated equilibrium was formed."

The reason why very few "in between" fossils were found is really quite simple. It takes an extraordinary amount of luck for fossilization to occur. The animal must die at the right time, in the right place, and the right series of events there after must occur for fossilization to even be a possibility. Very few animals are fossilized, and there are likely many species which have absolutely no fossilization records due to this.

Also, when looking at animals that evolve quickly, there is one thing that is usually common: They all have very low generation times(Time from conception to reproductive maturity). This allows genetic material to be shared faster, and thus evolution occurs much faster than in other animals. Elephants, for example, have evolved at a very slow rate compared to, say birds, which evolve at a very fast rate. Now, we can see markable differences in Elephant ancestors to contemporary Elephants, but upon close scrutiny, there really is not a great deal of difference in the overall structure. Birds, however, seem to evolve very quickly in comparison, with overall structure changing at a very rapid pace.

But, that's just me.

Cataclysms cause all kinds of changes, because sudden environmental changes basically mean "adapt or die."

It's not as fast as you seem to believe, it's just an increased rate of change due to changing environmental factors, broad changes to ecosystems and food webs. The faster the environment is changing, the faster a species needs to evolve, or perish. Those who do not adapt will die.

While one would think mass extinction events would increase resources, for some species, they might decrease resources, since when you kill off a bunch of different species, you're pulling links out of the food chain. Species aren't islands, what happens to the organisms around them affects them, directly or indirectly. If you take away an animal's food supply, it has to change to use a different supply or die.