Jump to content
pwagen

Alternative for natural selection

Recommended Posts

Firstly, I'm by no means whatsoever a biologist, so if I make false statements or using words wrongly or whatever, feel free to correct me.

 

Having followed the debate between creationists and scientists lately (and what a circus that is), I've been reading up a little on evolution as well as stalked a bunch of channels on Youtube, discussing the matter. And so, I hope I have at least a basic understanding of evolution and natural selection. One thing I'm curious about, however, is statements such as "natural selection is our best theory for how species evolve". I have no problem with that, whatsoever, and I agree with it. But statements like that begs the question; "ARE there any other theories"?

 

I know there's intelligent design, but I mean scientific theories. Natural selection, that individuals with certain traits more adapted to survive in the area they live in have a higher chance to pass on their genes to the next generation, I believe this to be a very solid theory with enough evidence to back it up ad nauseum, and I don't think there's anyone with an education actually doubting that's how we got to where we are today, on this planet. But let's say we have an alien planet. Of course, we can't know that much about any other planet right now. But speculatively (if that's a word), can we imagine there to be another process of evolution, based on something other than natural selection?

 

I've tried to think of something, but really can't. While my brother suggested selective selection (he explained it by having 2 banana flies and mating them until you get a fly with the traits you want), that requires an external force which controls it all. But it's not something that, to my knowledge, happens "in the wild". So if anyone can think of any such process, I'd be grateful.

 

But then again, I guess the natural in natural selection says it all :)

Share this post


Link to post
Share on other sites

How I see it is rather simple I think.

 

You have your various sources of variation (drift, mutation, etc) which all serve to generate diversity. Now at any one point, x amount of these will be beneficial to the organism in the current environment. Natural selection acts as a type of sieve that uses the environment to filter out what may or may not survive. This is where the concept of fitness comes in, the organisms that are most suited to the environment (most adapted) will have a higher probability of reproducing. That isn't to say that they will, but that if given the opportunity there's a greater chance of them producing offspring than a "less-fit" organism.

Share this post


Link to post
Share on other sites

You also have horizontal gene transfer, immigration/emigration (can be considered part of natural selection), gene flow, etc. But all of these can be thought of as part of natural selection due to the inheritance of the traits from parent to offspring.

Share this post


Link to post
Share on other sites

Well intelligent design can be seen in genetic grown flowers. But yet still natural at the same time so im not sure if that's the same or not.

Share this post


Link to post
Share on other sites

Yeah, I guess intelligent design in this case would be the same as artificial selection in this case? :)

 

But thanks guys, I'm about to abandon my idea of thinking up an alternative to natural selection (and moving on to winning the nobel prize and take over the world). Just don't see it happening, because any way you look at it, it seems we always come back to it. Just no way around it, and I'm quite content with that.

 

So cheers peeps!

Share this post


Link to post
Share on other sites

You also have horizontal gene transfer, immigration/emigration (can be considered part of natural selection), gene flow, etc. But all of these can be thought of as part of natural selection due to the inheritance of the traits from parent to offspring.

 

Your last sentence doesn't make much sense (to me at least) would you mind clarifying? As I understand it, HGT, Immigration, gene flow, mutation etc are all part of processes that generate variation, which is then acted upon by natural selection. Natural selection by itself does not generate diversity, it merely sorts out what it can and can't use. The principles are the same as for artificial selection (eg. using antibiotic resistance genes to probe for transformed bacteria) it's not the selection that brought about the change, it merely brought it to the fore. That's how I interpret it anyways

 

 

Well intelligent design can be seen in genetic grown flowers. But yet still natural at the same time so im not sure if that's the same or not.

 

Intelligent Design can be seen anywhere you wish. Humans will always try to make sense of patterns they don't fully understand, which is why ID has so many adherents. It's easy to see design everywhere.

Share this post


Link to post
Share on other sites

You have to be careful to differentiate between mechanisms that increase variability in the gene pool and those that change the composition. Roughly speaking natural selection and drift belong to the latter, mutations and recombinations to the former.

Edited by CharonY

Share this post


Link to post
Share on other sites

You have to be careful to differentiate between mechanisms that increase variability in the gene pool and those that change the composition.

To my uneducated self, those sound to be just about the same thing. Will definitely have to read up on the terminology.

Share this post


Link to post
Share on other sites

It is important to understand that there are at least two different variables. One the total elements within a population. This constitutes the complete genetic variability, i.e. all variations of all genes, for example. The second is their respective occurrence (frequency) within a population. Mutation, for instance, may add a new variant of a gene into the pool, thus enhancing the overall variance of the gene pool, when it appears. However the overall composition of the pool will hardly change as at the time of the mutation only one individual carries it. With no natural selection acting on it, the likelihood is very high that the mutation vanishes within a few generations.

 

If it there is high selective pressure to keep this novel allele, it can spread, thus increasing its frequency. The overall gene pool composition (i.e. frequency of each allele) will then significantly alter over time.

Share this post


Link to post
Share on other sites

If it there is high selective pressure to keep this novel allele, it can spread, thus increasing its frequency.

Can this be how, say, http://en.wikipedia.org/wiki/Peafowl developed their tails? It doesn't seem a large and colourful behind would be a good idea from a survival standpoint (easier to spot by predators, clumsy, makes you not as agile etc), so can it be argued that this came about by artificial (sexual) selection? The females preferring males with bright tails, making that trait prevalent despite being somewhat evolutionary detrimental?

 

Edit: Hopefully fixed link

Edited by pwagen

Share this post


Link to post
Share on other sites

Can this be how, say, peafowls"]http://en.wikipedia....eafowl]peafowls[/url] developed their tails? It doesn't seem a large and colourful behind would be a good idea from a survival standpoint (easier to spot by predators, clumsy, makes you not as agile etc), so can it be argued that this came about by artificial (sexual) selection? The females preferring males with bright tails, making that trait prevalent despite being somewhat evolutionary detrimental?

 

 

Yup you can say that, they actually performed a series of analysis on one or other bird of paradise and found that exact correlation, but only up to a point. The larger the bird's tail the more likely it was to get tail, but only up to a point, after which it was too heavy to fly and would get eaten by ground-based predators.

 

 

Share this post


Link to post
Share on other sites

The larger the bird's tail the more likely it was to get tail

I see what you did there!

 

Anyway, that's really fascinating. Makes me wonder how that got started. A colourful tail is a sign of a healthy individual, thus mating with that one would increase the chance of plenty of offspring? Does that mean we're back to natural selection again?

 

Thanks for all the helpful replies guys, really cleared everything up for me :)

 

 

Share this post


Link to post
Share on other sites

If evolution is the result of natural selection acting upon random modifications like mutations, IMHO it is more likely to observe evolution on small populations, and not on large ones.

Small populations can be found on small remote and isolate places like islands, or after a tragic reduction of population (due to a cataclysm), the bottleneck effect

On the same link the founder effect which I haven't thought about.

Share this post


Link to post
Share on other sites

Your last sentence doesn't make much sense (to me at least) would you mind clarifying? As I understand it, HGT, Immigration, gene flow, mutation etc are all part of processes that generate variation, which is then acted upon by natural selection. Natural selection by itself does not generate diversity, it merely sorts out what it can and can't use. The principles are the same as for artificial selection (eg. using antibiotic resistance genes to probe for transformed bacteria) it's not the selection that brought about the change, it merely brought it to the fore. That's how I interpret it anyways

 

I meant that if any of those things were to occur they would still be subject to natural selection so they are not necessarily different. They are more of a subset of what natural selection act upon. I was just throwing things out that are a part of evolution to help the OP understand the variability of things that can affect natural selection.

Share this post


Link to post
Share on other sites

I was just throwing things out that are a part of evolution to help the OP understand the variability of things that can affect natural selection.

Going back to your original statement, "But all of these can be thought of as part of natural selection due to the inheritance of the traits from parent to offspring", I just had a discussion on MSN leading to that very conclusion. After that discussion, it seems not even the example of the peafowls can stray away from natural selection. To quote him, "the genes that produce the big tails in males are the same ones that make females like big tails". So even though it may seem the decision is artificial, it's actually a process evolved via natural selection.

 

So basically, I can't really see how there would ever be a way around natural selection. I also realize it was a good idea I didn't become a biologist. Dawkins once said, I believe it was in a discussion with Neil de Grasse Tyson, something in the lines of "I think I'm more ignorant about your subject (astronomy) than you are about mine, simply because there is more to be ignorant about" (not exact quote, mind you). At the time, I thought he was right, but I'm starting to see biology is quite a complex subject in itself! And I'm growing more and more impressed with the people who actually understand the core of this.

Edit: Found the discussion.

 

Slightly misquoted him, but I hope the point didn't get lost :)

Edited by pwagen

Share this post


Link to post
Share on other sites

I know there's intelligent design, but I mean scientific theories.

 

Well intelligent design can be seen in genetic grown flowers.

 

Yeah, I guess intelligent design in this case would be the same as artificial selection in this case? :)

 

Intelligent Design can be seen anywhere you wish. Humans will always try to make sense of patterns they don't fully understand, which is why ID has so many adherents. It's easy to see design everywhere.

Let's be clear here. Intelligent Design does NOT exist. ID is a proven attempt to introduce religious teachings into public science classrooms in the US. Every single claim that ID proponents have made has been thoroughly debunked as creationism. Every. Single. Claim.

Share this post


Link to post
Share on other sites

Let's be clear here. Intelligent Design does NOT exist. ID is a proven attempt to introduce religious teachings into public science classrooms in the US. Every single claim that ID proponents have made has been thoroughly debunked as creationism. Every. Single. Claim.

I used ID instead of (I guess) artificial selection, not as the "theory" that creationists try to push into schools. I was afraid I.D. would come into the discussion sooner or later, so it was quite stupid of me to use it in that sense, thus bringing it in myself, and for that I apologize.

Share this post


Link to post
Share on other sites

 

To quote him, "the genes that produce the big tails in males are the same ones that make females like big tails".

 

Be very careful when people make statements like this, as it is most likely not true. In the first instance you are dealing with a (relatively) simple occurrence, size and colour of a tail. In the second, you are dealing with how the size and colour (separately) affect the female; i.e. The effect from the point where the signal enters they eye all the way through to the brain. Next you are dealing with the genes that regulate the awareness of the environment and stress factors; food, predation levels, temperature etc etc. Then your female will most likely have to be in heat as well, so you've got genes regulating that. Then you've probably got genes regulating behaviour that's along the lines of "Well if this tail is that big, shouldn't I wait and see if a bigger tail comes along?" as well as those that regulate "This tail is too small, that tail is too big, this tail is just right for me". I'm just hypothesizing, so take what I say with a pinch of salt

 

 

I also realize it was a good idea I didn't become a biologist. Dawkins once said, I believe it was in a discussion with Neil de Grasse Tyson, something in the lines of "I think I'm more ignorant about your subject (astronomy) than you are about mine, simply because there is more to be ignorant about" (not exact quote, mind you). At the time, I thought he was right, but I'm starting to see biology is quite a complex subject in itself! And I'm growing more and more impressed with the people who actually understand the core of this.

If that is indeed what Dawkins said, then as a Biologist I find that rather insulting. Biology is incredibly complex, you have intricate metabolic webs that regulate and self-regulate each other, highly complex biological codes that determine who, what and how you are. You don't just have the genome anymore, you have proteomes, metabolomes, and expressomes. Not only is it the information stored within your genetic code that determines what's happening, but the information in your proteins, in your enzymes even in the levels of certain metabolites in certain areas at certain times, and all of these fold back on each other and form this web of interactive regulation that is beyond our wildest dreams. And that's just if you're E.coli. If you go on towards higher forms of life, humans even, you have the brain to worry about, the nervous system, circulation, digestion; all of these coming together as one to perform the myriad of processes that allow you to think, to feel, to live and breathe.

 

And all of this is just the tip of the iceberg, there is wonder within ourselves that is beyond our wildest imaginings.

 

And of course, we can also trace this back to astrophysics. The elements that make up our bodies are born in the furnaces that are stars and are slung cosmic distances to settle here on earth. As Carl Sagan said "We are made of stardust". Some of the techniques that are used to analyse the world without, are also used to analyse the world within, spectrophotometry for example, radio-frequency analysis and I'm certain one or two more. How people can not see the beauty of science, the marriage of the seemingly impossible with the possible through thought and experiment is beyond me.

Share this post


Link to post
Share on other sites

If that is indeed what Dawkins said, then as a Biologist I find that rather insulting. Biology is incredibly complex, you have intricate metabolic webs that regulate and ...

I completely missed the insult. All I heard was a knowledegable person make a judgement call on which of two subjects was the more complex. I think perhaps you are finding insult where none was intended.

Share this post


Link to post
Share on other sites

I rather think Dawkins was just stroking Neil DeGrasse Tyson's ego and being polite when he said that (he actually said "I think there's more to be naive about").

 

There is no way astrophysics can seriously be claimed to be more complex than biology.

Share this post


Link to post
Share on other sites

(he actually said "I think there's more to be naive about").

Indeed. That's what happens when you quote from memory. I'm pretty sure Dawkins didn't mean to imply that biology was a simple subject. :)

Share this post


Link to post
Share on other sites

An alternative to Natural Selection would be something along the lines of inheritance of acquired characteristics, otherwise known as Lamarckism. Inheritance of acquired characteristics was disproved early on, but it was one of the first mechanisms for evolutionary change that was hypothesized. Sexual selection is not really an alternative to natural selection in the meaning of replacing it, but it is an alternative mechanism that can drive evolutionary change. Sexual selection is different than natural selection, because the most fit individual for the environment is not the one that will necessarily leave the most offspring. In the example of the birds of paradise, a male with a shorter tail would be better suited for the environment, in the sense that it could avoid predation longer leading to a longer life, which means it has more chances to have offspring. Instead the female selects a male with a long tail, which makes him less fit for the environment, but he will leave behind more offspring than the short-tailed more fit male. The argument from the good gene hypothesis of sexual selection has only been shown to be true in one paper, so it can't be assumed to be the norm. You might be more entertained by looking at the ideas of different levels of selection. This includes the good gene theory, the unpopular and not strongly supported hypothesis of group selection, and individual selection. It would also be useful for you to understand ideas like kin selection, which is explained by the good gene theory, altruism, and maybe also take a look at evolutionary game theory.

Share this post


Link to post
Share on other sites

I don't know the quote but it can be interpreted easily. I would argue that biology is far more complex than most of astrophysics, for which a lot of number of explanatory models exist. Not knowing them, expresses ignorance (the knowledge is there, but you may be unaware of it). Biological knowledge is very much fragmented with enormous gaps, due to its complexity. There are no good mathematical models for most of it. Most biologist know a lot about not knowing something.

 

Edit: did not see the second page. Bleh.

Edited by CharonY

Share this post


Link to post
Share on other sites

Most biologist know a lot about not knowing something.

 

 

Haha, that is so true. The limits of our knowledge at this point in time are impressive, yet the rate at which these limits are being pushed back is equally as astounding. We have in our department a group of scientists that have dedicated the last 30 years to a single enzyme and still they aren't quite sure exactly how it works/is regulated etc etc.

 

I fear the day though when people start looking at the relationship between quantum mechanics and biological systems o_0

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.