# Just curious here...



## acestro (Jul 7, 2003)

Now I'm sure there are a few members that could answer this well but
I figured I'd test the waters (so to speak) of everyone else's knowledge.

Who knows exactly how evolution happens. Use a fish for an example.

Note how you get multiple species from one, 
how they end up looking different,
how they become separate species, 
and what makes/keeps them separate species

Just firing up the scientific stuff, don't mind me! Reward for getting it right... respect and smilies I'd imagine...


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## traumatic (Jan 29, 2003)

For the most part, evolution as I understand it from one perspective, happens when a species is subjected to diverse adversity and it's ability to cope w/ changes to its environment. One species' adaptation to a new enviroment can include a number of abilities, such as breathing lower oxygen levels in the water, dealing w/ predators and searching for food. Of these adaptations, the physical properties of the animals change, such as body chemistry (genetic mutations), eyesight (bigger eyes), etc. These changes "create" different species. Of these new species, some will adapt, some will not be as successful.

I watched NOVA last night about lobed fin fishes walking on the sea floor and becoming land animals.


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## Burf (Nov 3, 2003)

hybridisation, polyploidy, allopatric speciation, sympatric speciation, blah, blah, blah

I've just sat a few classes on this subject so i have a bit of an unfair advantage here, i'll let someone take my hints above and give a "proper" answer.

i'm just too tired busy to be honest, but if need be, ill write a full answer when i get up in the morning :nod:


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## acestro (Jul 7, 2003)

If you want to take it to another level, only one of those things you listed is really responsible for most of speciation. Which do you think it is?









You're close on a lot of accounts, traumatic, but species don't react to situations by creating new adaptations. This is a confusion that persists even in biology graduates. Bottom line; either you're ready or you're not. Meaning: either you have the variety to adapt and diversify or you don't.


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## Tinkerbelle (Oct 14, 2004)

it all comes down to selective breeding. those that live long enough in their respective environment gain the right to pass on their genes.

this however, does not seem to relate to anything that has been domisticated. just take the dog for example. its almost difficult to believe that a pug dog's ancestry comes down from a wolf, and that yes, they can interbreed. even betta fish have been purposefully selectively bred for longer fin traits, sadly, in the wild these would be at a disadvantage. I wonder how much humans really have mettled with the do process of evolution?


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## acestro (Jul 7, 2003)

Not to be snooty, but it's interesting to see the gaps in knowledge here....

No one's quite hit it yet. There are key ways for genes to change and a key element to help species get created.


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## MR.FREEZ (Jan 26, 2004)

i have just a simple understanding of evolution but its enough for me to really believe in it

more then anything else, it goes like this

all you need is isolation, time, and necessity



> Note how you get multiple species from one,
> how they end up looking different


/\isolation will take care of that



> how they become separate species


/\ time takes care of that



> and what makes/keeps them separate species


/\ necessity does that


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## acestro (Jul 7, 2003)

Good response.

However, time alone can't make species.

Necessity is something that can't be understood by "species" the way
we understand it. I'll let things stew a while before I drop my angle.


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## Guest (Nov 1, 2004)

(I'll give this a guess - be easy on me, I'm just a factory worker :laugh: )

Random genetic mutations occur in any given population of animals.

Some of these mutations are expressed as physiological characteristics that give the individual animal advantages over the other animals These advantages allow the individual animal to to live longer and create more offspring - thus multiplying the genes that create the advantageous physical characteristics.

Over a given period of time, the population of animals as a whole takes on these advantageous characteristics by genetic inheritance.

When animal populations of the same species are separated by a boundary, they can diverge genetically far enough apart to be considered separate species.


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## Polypterus (May 4, 2003)

This is an ammusing thread, I'll wait a bit to comment as
I'd like also to see some more posts and ideas.


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## MR.FREEZ (Jan 26, 2004)

acestro said:


> Good response.
> 
> However, time alone can't make species.
> 
> ...





> Necessity is something that can't be understood by "species" the way
> we understand it. I'll let things stew a while before I drop my angle.


i meant it more like, how a birds beak would find it nessecary to adapt to a

certain new seed that it would have to eat to live. i wish i had the vocabulary to exlpain it.

bull snake did a good job at it. ill give it more thought and maybe later i it'll come to me


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## acestro (Jul 7, 2003)

But the "need" isn't recognized by a species. There is definitely a "need" out there for animals having wheels for locomotion. I'm not being silly, stay with me on this. The problem is they can't evolve wheels. Secondly there would definitely be a need for turtles in northern areas to grow fur and produce internal heat. Again, silly, but the fact is they haven't or can't make the leap. You bring up a greatly understood subject called "phylogenic constraint".

Bullsnake got two big points. Genetic Mutation being one factor to change genes.
More importantly the isolation of populations. Just a little off here, the populations are thought to be unchanged until after separation.

The key point of separation of species and then their evolution is "allopatric speciation".

But there's a few more important ways that species can change besides genetic mutation......

And how to keep new species separate.....


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## MR.FREEZ (Jan 26, 2004)

acestro said:


> But there's a few more important ways that species can change besides genetic mutation......
> 
> And how to keep new species separate.....


 what if the same species went two different ways cause of two different preffered foods kinda thing


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## acestro (Jul 7, 2003)

Dietary shift does happen, seems to be potentially a big deal with African cichlids.
But this still requires separation (allopatry), probably, and mutation. There can be something else driving that change in diet.....


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## MR.FREEZ (Jan 26, 2004)

acestro said:


> Dietary shift does happen, seems to be potentially a big deal with African cichlids.
> But this still requires separation (allopatry), probably, and mutation. There can be something else driving that change in diet.....


 the loss of a certain food that the species is specialized in??


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## Guest (Nov 3, 2004)

> But there's a few more important ways that species can change besides genetic mutation......
> And how to keep new species separate.....


Environmental and climatic differences?
For example, the Artic fox evolving a white pelt while the grey fox evolved a grey-brown pelt.


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## acestro (Jul 7, 2003)

You guys are stuck in neutral. Those are selection pressures and mutations that are selected for. Being thus, I'll help out and bump you into the category of "natural selection". Basically nature choosing certain genes over others (new diet, new colors). It needs variety of genes to act on.

Mutation
Natural Selection

From here it starts to get a little tough, but there's three more.... for a hint, think Hardy and Weinberg...


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## Death in #'s (Apr 29, 2003)

the gist of the concept is that small,random,heritable diffrences among individauls result in diffrent chances of survival and reproduction-success for some,death without offspring for others-and that this naturalculling leads to significant changes in shape,size,strength,armament,color,bio chemistry,and behavior among the descendants.excess population growth drives the competitive struggle.becauase less successful competitors produce fewer offspring ,the useless or negative variations tend to be perpetuated and gradually magnified throughout a population.

:laugh: hope this makes sense to you guys


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## CrocKeeper (Dec 26, 2003)

A very seriously cool thread Acestro!!!









I wish I had been here at the start...

I add these to the brain storm for those seriously wanting to answer what Ace is looking for...hehe, homework if you will....and to be fair I will add another link that covers creationary thought as well since both are hypothetical....









http://www.ucmp.berkeley.edu/history/evolution.html

http://www.talkorigins.org/


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## acestro (Jul 7, 2003)

Oh no, let's not get started on creationism....
















The concepts of natural selection and mutation seems well understood, allopatry too. There's another kind of selection (which really falls under nat'l selection) and a couple of ways genes can go (or come...)...


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## acestro (Jul 7, 2003)

Gene flow
Genetic drift
Sexual Selection
Mutation
Natural Selection

Usually operating with allopatry (a divided population)

And they don't change in the exact same ways, making new species where once there was one!

Simplified, of course, but it's cool when you look at how geography has separated biology and how evolution matches this pattern. Anyhow....


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## acestro (Jul 7, 2003)

re-opening this, miss crockeeper though







Any evolution thoughts/questions?


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## piranha45 (Apr 8, 2003)

View attachment 138834
what does the phylogenetic tree for the popular aquarium-fish families of Actinopterygii look like? know of any links?


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## acestro (Jul 7, 2003)

I can show you links but I dont know of any that go down to families for such a large group. Lemme check...

This helpful?


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## piranha45 (Apr 8, 2003)

nice find!


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## Ex0dus (Jun 29, 2005)

acestro said:


> Gene flow
> Genetic drift
> Sexual Selection
> Mutation
> ...


Explain sexual selection. Im familiar with the rest. Is sexual selection known by something else? In my anthropology classes the list of 5 consisted of all those with the exception on sexual selection.


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## acestro (Jul 7, 2003)

Sexual selection is sometimes considered part of natural selection. This isn't completely appropriate because some of the sexual selection traits have no value in terms of natural selection (for example, long feathers in peacocks).

Two kinds of sexual selection; male-male combat=when males compete for mates sex. sel. favours traits that help them win. This is seen in large males that fight (gorilla, deer). It also is seen in 'gear' like antlers.

Female-choice is the other sex.sel. and this is when the female picks traits of the male. This is where colorful males come from in fish, birds, etc. Females can also choose for size (if the male defends the young), so there's some blending with male-male combat.

There are more elaborate examples of this too (some insect males offer a sugary 'treat' to females, bower birds construct complex nests, snakes such as rattlesnakes, copperheads, and some pine snakes actually have males fight). Helpful?


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## Piranha Guru (Nov 24, 2005)

Great topic acestro. One thing that needs to be stressed, and I think Dr. Green hit upon this a little bit, is that evolution occurs within POPULATIONS, not individuals (individuals don't "choose" to evolve). My high school students have the hardest time with this. It is the combined genetic changes of a population that ultimely gives rise to new species. The smaller the population, the more rapid the speciation by factors such as mutation. African cichlids and adaptive radiation is a great fish example of how one species could give rise to many.


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## acestro (Jul 7, 2003)

BioTeach said:


> Great topic acestro. One thing that needs to be stressed, and I think Dr. Green hit upon this a little bit, is that evolution occurs within POPULATIONS, not individuals (individuals don't "choose" to evolve). My high school students have the hardest time with this. It is the combined genetic changes of a population that ultimely gives rise to new species. The smaller the population, the more rapid the speciation by factors such as mutation. African cichlids and adaptive radiation is a great fish example of how one species could give rise to many.


I think stressing the nature of allopatry helps with that. It always seemed to help to have cool examples too. Although I'm sure I was biased in thinking that my cichlid and snake examples were cool. If there's a good example in your part of the country that helps too; they can go outside and say they know something about what is in their backyard, also you can bring the critters in.


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