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+--- Thread: Evolution Vs. Adaptation (/showthread.php?tid=42216)
Evolution Vs. Adaptation - Kalovale - 2011-05-23
I have learned something like this in biology back in the day, but I wasn't too terribly into it and it was taught in Vietnamese anyway, so I basically have no clue.
Generally, the idea is this: Almost everything we physically (and sometimes, symbolically) see today exist because they survived a process of natural filtering.
Survival of the fittest. Humans, chimpanzees, lions, certain types of moths that survived the Industrial Revolution, etc...
However, when I think about African people and this thing I heard in biology class about their genes being the prominent (therefore oftentimes better) ones: dark curly hair, tanned skin, etc.., I can't help but wonder where adaptation stands in all this, since they certainly did not originate from a different ancestor from ours, or did they?
Surely all lives strive to survive and get changed in one way or another during the process, but whether or not that can be passed on is not guaranteed, is it? However muscular a dad might be doesn't say anything about his son; but the dad's quality of chivalry might very likely pass on and reflect in later generations.
How should I look at, say, a chameleon's ability to change its colors? Is that a by-chance ability that the lizard adopted during mutation or something they worked so hard on and finally achieve? What about birds' ability to fly? What about us humans? On what basis are we different?
Evolution Vs. Adaptation - Nalek - 2011-05-23
I know 8th graders who know the answers to these questions. Just saying.
Evolution Vs. Adaptation - Eos - 2011-05-23
http://en.wikipedia.org/wiki/Natural_selection
Also, while the traits of Africans are the more dominant, they're not necessarily optimal to survival outside of Africa.
Different subspecies of humans evolved because their particular adaptations were more advantageous to survival in different climates, and in many cases throwbacks were weeded out by cultural selection until recessive were breeding with recessive until the theoretically more dominant genes were diluted out.
Evolution Vs. Adaptation - Takebacker - 2011-05-23
Kalovale Wrote:On what basis are we different?
Sentience, apposable (sp?) thumbs?
Evolution Vs. Adaptation - Kalovale - 2011-05-24
Eosian Wrote:http://en.wikipedia.org/wiki/Natural_selection
Also, while the traits of Africans are the more dominant, they're not necessarily optimal to survival outside of Africa.
Different subspecies of humans evolved because their particular adaptations were more advantageous to survival in different climates, and in many cases throwbacks were weeded out by cultural selection until recessive were breeding with recessive until the theoretically more dominant genes were diluted out.
I've always assumed the genetic change to not be related to the living conditions, but I'll read through that anyway to see if it actually is.
The point I was trying to make is how exactly do traits get passed on genetically. Surely if you get exposed under the sun for a long time, that will tan your skin, but it will not necessarily alter the genetic information in your reproductive cells. I can see how exposure to high radiation can ionize the chemicals and make random changes to your body's building block (thus causing abnormal traits which can be passed on) and that has remained the only cell alteration method I know of.
From your post, I could get: People in a certain area remain dominant in population because their "adaptations" are more/most suitable to surviving in said area, which, if I recall correctly, is natural selection. This sounds much the same as the case of the peppered moths.
There was also the idea that people with recessive genes would be culturally forced to mate with one another and thus reducing/eliminating the population holding the recessive genes, but I'm half skeptical that I'm just seeing things on this one because it doesn't really make sense.
I guess in a nutshell, what I'm wondering is related to this article and the reverse idea of it. Adaptations can happen despite what the genetic information would suggest, and some adaptation are reflected back into the genes. But how?
Evolution Vs. Adaptation - Eos - 2011-05-24
Genetic traits are not passed on as perfect copies, they mutate and variate generation by generation, creating new effects and the ones that survive get passed down. The ones that lessen the viability of life result in death and therefore do not get passed down (often), the rest do whether they're neutral or beneficial, with the more beneficial being more likely to persist and the neutral more likely to continue permuting.
It's not necessarily that we adapt to suit our environment, it's more than those who've developed adaptation more suitable to the environment have a better opportunity to pass on those traits until they become a subspecies unto themselves.
An easy example being green lizards. Lizards may spontaneously develop in other colors, red, blue, purple, but the ones who come up in green blend better with their environment. They didn't choose to be green to survive, they survived because they happened to be born green and the others didn't and therefore didn't live to pass on their genes. Green team won.
Evolution Vs. Adaptation - Kalovale - 2011-05-24
Eosian Wrote:Genetic traits are not passed on as perfect copies, they mutate and variate generation by generation, creating new effects and the ones that survive get passed down. The ones that lessen the viability of life result in death and therefore do not get passed down (often), the rest do whether they're neutral or beneficial, with the more beneficial being more likely to persist and the neutral more likely to continue permuting.
It's not necessarily that we adapt to suit our environment, it's more than those who've developed adaptation more suitable to the environment have a better opportunity to pass on those traits until they become a subspecies unto themselves.
An easy example being green lizards. Lizards may spontaneously develop in other colors, red, blue, purple, but the ones who come up in green blend better with their environment. They didn't choose to be green to survive, they survived because they happened to be born green and the others didn't and therefore didn't live to pass on their genes. Green team won.
I understand natural selection, which was why the chameleon's example was used (to demonstrate pure natural selection vs a later example that reflects environmental adaptation). Else, my first sentence wouldn't claim that almost everything today exists because they simply by chance were "chosen" to.
I think the keyword in your post is "mutate". As I've only studied genetics with beans and flies, the genetic traits did in fact get passed on perfectly.
However, for things to change, there has to be change somewhere in the process. I'm aware of the ways through which genetic variation takes place, mutation and/or alteration in chromosome number/shape/size and such.
The thing I can't wrap my mind around is what exactly drives that variation? Is environmental condition a candidate? Is it just purely by chance (random mutation that happens regardless of any other factor, even time) and anyone lucky enough to be chosen to move on will continue breeding offsprings? Is it somewhere in the middle? And where?
Evolution Vs. Adaptation - Eos - 2011-05-24
Kalovale Wrote:The thing I can't wrap my mind around is what exactly drives that variation? Is environmental condition a candidate? Is it just purely by chance (random mutation that happens regardless of any other factor, even time) and anyone lucky enough to be chosen to move on will continue breeding offsprings? Is it somewhere in the middle? And where?
It can be environmental; ie: UV radiation (sunlight) can alter DNA as can chemical exposure and numerous other things and it can occur just due to freak chance. There is no solid answer for all of it because in most circumstances we have no idea what the variables are. You didn't see variation in your tests because they were too tightly controlled, no chance for external stimuli to introduce deviations and not enough generations for nature to have done it itself.
Evolution Vs. Adaptation - OB3LISK - 2011-05-24
Yay green! Hold on lemme read that wiki page on plasticity and then I'll respond.
*will probably forget about this thread and by the time I come back I won't be in a reading mood*
*as if I was ever in a reading mood LOL you got scammed by reading this post*
Evolution Vs. Adaptation - Mira - 2011-05-24
Genetic variability in a population also comes from genes crossing over in meiosis and independent assortment of genes during meiosis. Combine that with possible, but rare, mutations and you can produce a number of different combinations. I think a single human pairing can produce 2^(23) x 2^(23) possible different combinations of gametes without mutations. Mutations can appear for a number of reasons, and Eos said the more common environmental ones. DNA may also be copied wrong (in gametes) and that mistake or mutation would be passed onto the offspring.
Evolution does not happen in an individual. Populations evolve. Over time, individuals who cannot survive are not as successful as individuals who have traits that let them survive and mate as a higher rate. Eventually these successful traits become prevalent in the population. It seems your confusion comes from a very limited knowledge on the subject; reading books about it or just reading articles online should clear up many of your questions, if you want to learn more.
Edit: You should read about the central dogma, too.
Evolution Vs. Adaptation - Kalovale - 2011-05-24
Eosian Wrote:It can be environmental; ie: UV radiation (sunlight) can alter DNA as can chemical exposure and numerous other things and it can occur just due to freak chance. There is no solid answer for all of it because in most circumstances we have no idea what the variables are. You didn't see variation in your tests because they were too tightly controlled, no chance for external stimuli to introduce deviations and not enough generations for nature to have done it itself.
Yeah, radiation, viruses, chemicals seem environmental (though that's far from enough) whist genetic transposition and/or errors in reproduction seem pretty random to me.
That certainly did put one new thing into perspective: Environments COULD drive the mutations while fitness guides the selection. Without external factors, few (or just less) changes would happen (I recall there being background genetic variation, but I have no clue what it is).
Once driven, the changes are selected for/against and produce the 'final' result of the fittest variation.
Those two are pretty separate.
@ Mira: I have to admit Biology and Chemistry are two of my least favorite subjects.
Evolution Vs. Adaptation - Eos - 2011-05-24
Kalovale Wrote:I recall there being background genetic variation, but I have no clue what it is
Mira covered that part. Didn't want to get that technical since this is Speakeasy not Rubik's Cube and you're asking more middle school level questions, so i was keeping it at the punnett square level.
Evolution Vs. Adaptation - Mira - 2011-05-24
Sun tanning is actually a really good example to use for this.
When you tan, your body is actually going through a cause-and-effect cycle. The increased exposure to UV light causes the pigment cells (melanocytes) in your skin to produce more melanin, the pigment that causes your skin to be darker. Without being tan, the amount of melanin your skin produces is genetic. DNA codes for, ultimately, proteins. These proteins shape your phenotype. More then one gene is responsible for skin color in humans and the combination of all these genes working together produces your skin color. A population evolves to become more tan in a high UV exposure environment when individuals who are genetically more tan end up surviving more then individuals who have genetically lighter skin, and having darker skin becomes more prevalent in the population. The darker individuals have more success because melanin blocks UV light from damaging DNA, so having that natural advantage is the key in this hypothetical scenario. The UV damaging the DNA and causing mutations isn't the source of variation and evolution (solely); the most successful individuals surviving and reproducing is.
The environment is what drives natural selection. Those individuals that can survive in the environment reproduce; those that cannot survive in their environment do not get that chance. New traits that arise from mutations are also subject to natural selection. If that trait is beneficial, it may become a dominant trait in a population. If it's not beneficial, it will probably die out. I hope I explained that ok.
Evolution Vs. Adaptation - Kalovale - 2011-05-24
Mira Wrote:Edit: You should read about the central dogma, too.
Isn't this basically this:
Quote:I've always assumed the genetic change to not be related to the living conditions.However one's physical traits may change won't affect the genetic make-up of that particular individual directly.
This is funny because I now realize it's the very concept of OOP. Store states inside and interact on the outside through functions.
Also, the idea of natural selection is clear; what I want to know is how it happens in the first place.
I understand that it is central to modern biology and it is often misunderstood as "evolving to a better state", but that is not the case here and I think I've failed to establish that, so I'm explicitly stating that now.
Okay, so we have 2 factors after all these posts: background genetic variations through reproduction and environmental variations.
Let's put environmental variation out of the picture for a moment.
Now we have an Asian lineage. Chances are that an Asian couple, though having potentially 2^32 x 2^32 possible combination of gamete coupling, will give birth to a fairly Asian-looking boy. Granted, his genetic information will be far different from that of either of his parents, but the outward traits shouldn't be outrageously varying.
This is probably accountable for geniuses emerging from time to time, but it surely isn't going to explain how fish started to walk on land. Even if it is, I'm not going to either easily or readily understand how.
With just this alone, I believe there will be no major "evolution" as time passes. After all, humans are humans, we aren't going to grow fins, scales and maybe another eye just because the ground gradually sinks into the sea.
And we will be wiped out, most likely.
So that sort of puts me under the impression that major changes in history was driven by something else, something that breaks the cycle, something from OUTSIDE the cycle.
Though, environmental effects aren't exactly reflected in genetic levels, as suggested by the central dogma (again, muscular dads don't produce muscular boys), so they don't really contribute to the variety of alleles there are.
So it must be something else, that I concluded. What is that something else? I knew of radiation (often known to cause cancer, which is most likely an undesired mutation), mishaps in reproduction, viruses, etc... but none of that would explain even the skin color of different people in different continents.
This has been bugging me until earlier when it suddenly dawned on me that environment could DRIVE the mutation whereas natural selection will guide it; the two are fairly separated. Such as people in a highly radioactive area have a higher chance to mutate. The ones who mutate the "right way" will be fittest to live in that area (e.g: shorter height for instance because there is a beast that hunt tall people). Without the radiation, no people will have the chance to become short enough to survive, for example.
They may also host less desirable mutations such as cancer, but in the general picture, they are more fit to live in that particular area than those without cancer but too tall.
Makes sense.
Evolution Vs. Adaptation - Mira - 2011-05-24
A lot of the assumptions you make aren't completely correct. If you want me to go into detail how you're wrong, I can, but I'm not that sort of person. You really should read a book on evolution and natural selection. It would probably clear up a lot of the confusion and misconceptions you have about the subject. My AP biology teacher suggested reading Your Inner Fish if we were interested in the subject.
Also, your assumption of what the Central Dogma is incorrect. The Central Dogma is the pathway from DNA to RNA to protein (And RNA to DNA, but that's for certain viruses [like retroviruses] mostly, as far as I know). It helps you understand the basic concepts of how DNA works so you can understand how traits are expressed as a phenotype.
Evolution Vs. Adaptation - Kalovale - 2011-05-24
Mira Wrote:Also, your assumption of what the Central Dogma is incorrect. The Central Dogma is the pathway from DNA to RNA to protein (And RNA to DNA, but that's for certain viruses [like retroviruses] mostly, as far as I know). It helps you understand the basic concepts of how DNA works so you can understand how traits are expressed as a phenotype.
It also poses the pathway from protein back to the DNA and claim that to be unprecedented. Essentially, it formally describes the fact that genotypical patterns are reflected on the phenotype and not the other way around and the mechanism behind that fact, which is details, not "basically".
And it would be fine to point out my misconceptions. I'm here to learn.
Evolution Vs. Adaptation - Corn - 2011-05-24
Kalovale Wrote:Isn't this basically this:
However one's physical traits may change won't affect the genetic make-up of that particular individual directly.
You're correct on this.
This is funny because I now realize it's the very concept of OOP. Store states inside and interact on the outside through functions.
Also, the idea of natural selection is clear; what I want to know is how it happens in the first place.
People with worse traits die off. People with better traits live and pass on their traits through the population.
I understand that it is central to modern biology and it is often misunderstood as "evolving to a better state", but that is not the case here and I think I've failed to establish that, so I'm explicitly stating that now.
In Africa, black-skin is more prominent because, well, I don't need to repeat it. It's easier to survive being black-skinned than white-skinned there.
Okay, so we have 2 factors after all these posts: background genetic variations through reproduction and environmental variations.
Let's put environmental variation out of the picture for a moment.
Now we have an Asian lineage. Chances are that an Asian couple, though having potentially 2^32 x 2^32 possible combination of gamete coupling, will give birth to a fairly Asian-looking boy. Granted, his genetic information will be far different from that of either of his parents, but the outward traits shouldn't be outrageously varying.
This is probably accountable for geniuses emerging from time to time, but it surely isn't going to explain how fish started to walk on land. Even if it is, I'm not going to either easily or readily understand how.
Fish walked on land because one magical day there was this one fish that had genes mutated to go onto land. It was gradual. It probably started out as reproducing in water, but living on land, and eventually, it became full-blown onto land.
With just this alone, I believe there will be no major "evolution" as time passes. After all, humans are humans, we aren't going to grow fins, scales and maybe another eye just because the ground gradually sinks into the sea.
And we will be wiped out, most likely.
Exactly. We will get wiped out...you do realize 99% of all species are wiped out. The 1 remaining % is still living because they evolved to those conditions over tens and tens of millions of years. Evolution is not gradual. Earth is 4 billion years old. There's plenty of time.
So that sort of puts me under the impression that major changes in history was driven by something else, something that breaks the cycle, something from OUTSIDE the cycle.
Bottleneck effect.
Though, environmental effects aren't exactly reflected in genetic levels, as suggested by the central dogma (again, muscular dads don't produce muscular boys), so they don't really contribute to the variety of alleles there are.
Evolution.
So it must be something else, that I concluded. What is that something else? I knew of radiation (often known to cause cancer, which is most likely an undesired mutation), mishaps in reproduction, viruses, etc... but none of that would explain even the skin color of different people in different continents.
Because black-skinned people are better suited to living there. Humans have been around for several million years. That's enough time for something minor as skin color to mutate.
Comments in bold.
Cracked article on the fastest evolving animals currently.
Evolution Vs. Adaptation - Kalovale - 2011-05-24
Corn Wrote:Comments in bold.
Cracked article on the fastest evolving animals currently.
The problems with your explanation is that it is no explanation at all.
We all know the direction of natural selection, but natural selection requires variations in the first place in order to select. Like in my (perhaps overstretched) example of us humans unable to become fish-like, if we just keep on breeding amongst ourselves normally, there could be a bunch of variations and it won't even make ONE of us grow fins or absorb enough oxygen dissolved in water. Something has to happen to allow mutation to happen (background factors like radiations, viruses, reproduction errors, etc...) in the first place before natural selection can jump in on the fun and say "Hey, this guy transformed the right way, I'ma just let him live."
Even if you know where you should be going, if you don't have the means to start going at all, you'll still wind up nowhere.
Evolution Vs. Adaptation - hadriel - 2011-05-24
The environment is a part of NS. What drives NS is the fitness of the phenotype arising from a change in the genotype i.e. mutation.
NS leads to the selection of a particular phenotype while putting pressure on those with less viable phenotype at that period of time and place, and gradually as more genotypic variations occur you eventually come to a point where a whole new species is formed because so many changes in genotype has occured. This is one of the processes of speciation. Lots of other processes too.
A note for you is that mutations can be neutral, can be positive or can be negative. neutral mutations have no selection pressure for them, so if you e.g. have blue eyes instead of brown eyes, it's not going to make a hell of a diff to your survivability (unless there are madmen who hunt blue-eyed things). Positive mutations are those that confer greater fitness in the local environment e.g. you have 5 digits on your hand, and some miraculous mutation gave you 6 digits that allows you to have greater dexterity blah blah, so because of NS you "survive better" blah blah blah. Same thing, if you have some miraculous mutation that gave you 4 digits... blah blah blah. Not everything that is present now is necessarily 100% due to NS! Mutations are RANDOM, and NS depends on the local environment [and any changes to that local environment]. A mutant phenotype may be neutral in one environment, or may be selected for/against in another. And likewise, we have such things as convergent and divergent mutations.
A common example to show NS (accelerated) is in antibiotic resistance in bacteria. Say you have an infection. You see the doc, he gives you ampicillin. You take most of the pills. The ampicillin kills MOST OF THE BACTERIA (beta lactams only kill bacterial cells that are actively growing) and the remaining little bit is left for your immune system to finish off. You didn't finish the entire course of antibiotics. The little bit of bacteria that managed to survive the antibiotic treatment is said to have increased fitness for some reason or another e.g. has a mutated gene that ampicillin does not work on. Your immune system did not manage to eradicate all the remaining bacteria with increased fitness. This fitter bacteria now grows and multiplies. So you fall sick again, and you see the doc. So he gives you Amoxiclav. And so on... So what did you learn today? EAT THAT BLOODY PILL OR ELSE YOU FALL MORE SICK AND INFECT OTHER PEOPLE WITH YOUR SUPERBUG THAT'S FKING HARD TO TREAT!
A better example would be in the lab. You have a bacteria with no resistance to Kanamycin. You take a colony of bacteria and attempt to transform them so that they now have an antibiotic resistance gene. You culture them in an LB plate with Kanamycin. So of all the bacteria that has been plated, those transformed bacteria [i.e. "mutated"] now has been conferred resistance to Kanamycin, and so has greater fitness. Those that didn't get transformed will be susceptible to Kanamycin, and will face selection pressure. In this case, Kanamycin is acting as the selection pressure. The process of selecting the transformed bacteria against the non-transformed one is called NS.
So, in that plate with Kanamycin, mutations can occur. Negative mutations would be selected against e.g. mutating the Kanamycin resistance gene making it inactive, so obviously these negative mutants will have decreased fitness and will therefore die, because the selection pressure, Kanamycin, is still present. Neutral mutations would probably include inserting random DNA bits into non-important parts of the chromosome, or mutating an enzyme that is not important in the current environment - no selection pressure for/against. Positive mutation would probably be something like... gaining an extra copy of the Kanamycin resistance gene, making it have even greater fitness in the current environment.
If I, let's say, take the selection pressure off by sub-culturing the bacteria in an LB plate without Kanamycin, then ALL of the mutations can occur, because there is no selection pressure to select for or against any of the variations. So the bacteria could very well mutate and have a defective Kanamycin resistance gene now, and nothing will happen to it because it's neutral in the current environment.
Evolution takes a very long time - it takes so many years before the numbers of one genotype completely swamp an area and a less-fit genotype dies out. That's because mutations are so rare - it's random and caused by the environment, and occurs at a ridiculously low rate. Nobody really knows where evolution is headed, for very obvious reasons like we don't know what's going to happen in the future, what selection pressures would be present etc.
Alright, if you want any further detailed explanation, go to Rubik's Cube please.
Hadriel
Evolution Vs. Adaptation - Corn - 2011-05-24
Kalovale Wrote:The problems with your explanation is that it is no explanation at all.
We all know the direction of natural selection, but natural selection requires variations in the first place in order to select. Like in my (perhaps overstretched) example of us humans unable to become fish-like, if we just keep on breeding amongst ourselves normally, there could be a bunch of variations and it won't even make ONE of us grow fins or absorb enough oxygen dissolved in water. Something has to happen to allow mutation to happen (background factors like radiations, viruses, reproduction errors, etc...) in the first place before natural selection can jump in on the fun and say "Hey, this guy transformed the right way, I'ma just let him live."
Even if you know where you should be going, if you don't have the means to start going at all, you'll still wind up nowhere.
I don't get what you're talking about. There's variations in the first place to select in the case of humans due to mutations/sexual diversity.