Okapi, excellent genes and evolution.

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Okapi, excellent genes and evolution.

Postby 0.0 » Sun Apr 10, 2011 3:31 am UTC

I just found out that Okapi aren't extinct, endangered, nor mythical. Of course I'm speaking of the fabled half-horse half-zebra looking animal. Turns out there are somewhere between 10,000 and 20,000 living in Africa today. It was thought of as the African unicorn for quite some time, until scientists were presented a skull and skin at some point in the early 20th century. That got me thinking about animal species populations that dwindle down to minute numbers like the cheetah or the Andes condor. Think about how an entire species dwindles and how that affects the nature of the surviving population. The environment, disease, new competition and lack of easy food are all reasons for decreasing populations. And loss of home by increasing human footprint. all these things push a common focus, and that is increased competition for food, habitat, and reproduction by a single species. Now expand this out over several generations, possibly hundreds or even thousands of years and now the population has dwindled to less than ten. Any one of these specimens would represent the best of the best of that species; Would it not? My thought is: If a species like the cheetah dwindles down to a small number, there by rectifying the unbalance between the harshness of its current environment with its natural ability to survive (assuming humans weren't the cause), would it then be able to naturally repopulate just from this sort of super survival of the fittest filter? Has this phenomenon happened before? And could it be a mechanism to leap evolution ahead when it is mostly needed?
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Re: Okapi, excellent genes and evolution.

Postby Jakell » Sun Apr 10, 2011 4:15 am UTC

0.0 wrote:Any one of these specimens would represent the best of the best of that species; Would it not?


Not at all; if animals are externally forced down to a small population, the inbreeding can be far too deleterious to have a chance of being beneficial. The fact that those animals survived does not mean that they are the best, perhaps they are just the last.
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Re: Okapi, excellent genes and evolution.

Postby Izawwlgood » Sun Apr 10, 2011 5:54 am UTC

0.0 wrote:Any one of these specimens would represent the best of the best of that species; Would it not?

I'm not sure why you'd think that at all. it's like saying "If I choose 1,000 people at random from the world, what's to say they of them isn't the smartest, best fit, most disease resistant individual on Earth?". What makes you think this would be the case?

0.0 wrote:rectifying the unbalance between the harshness of its current environment with its natural ability to survive

Can you explain what this means? Why are you assuming that the thing that's causing the population to dwindle is solely competition with other members of the species?
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Re: Okapi, excellent genes and evolution.

Postby Bears! » Sun Apr 10, 2011 7:41 am UTC

0.0 wrote:My thought is: If a species like the cheetah dwindles down to a small number, there by rectifying the unbalance between the harshness of its current environment with its natural ability to survive (assuming humans weren't the cause), would it then be able to naturally repopulate just from this sort of super survival of the fittest filter?


This generally is not the case from an evolutionary perspective. The point is this: natural selection doesn't usually produce a super-fit population of a species, even if the individual members of the population are very, or even the most, fit. This is due to the need for genetic variability. You mentioned the cheetah, presumably because you're familiar with the bottlenecking this species experienced not too long ago; this example illustrates the point perfectly. The bottleneck dramatically reduced genetic variability within the species, and as a result, Cheetahs experience many problems such as low sperm count. Because of their low genetic variability they are also susceptible to particularly virulent feline viruses. Since there is such little genetic variability within the population, cheetahs may very well become extinct from such a virus since the likelihood of them possessing an immunity gene as a population is extremely low.

Has this phenomenon happened before?


Interestingly, this phenomenon is thought to be a possible explanation for the survival of early Homo sapiens. The African environment became particularly harsh during the early years of our species's existence (200kya, though this is debated), and the human population dwindled significantly (some speculation leads anthropologists to believe that this is the origin of the "mitochondrial Eve"). Fortunately, a hallmark of humanity is our intelligence, and with intelligence, you have a whole new bag of adaptability. This is precisely what makes the case of humanity's bottleneck and subsequent repopulation so unique - our unique intelligence. Early Homo sapiens had the ability to overcome extreme environmental odds through the use of its intelligence, but presumably only the "most intelligent" survived. Clearly, this scenario is based on a large amount of speculation. We aren't even certain of what our evolutionary history looks like completely, even our geographical origins; however, this scenario is very plausible, so it does lend a very small amount of credence to your thinking.

And could it be a mechanism to leap evolution ahead when it is mostly needed?


This is flawed thinking. Species do not evolve because fitness is "needed" per se. They evolve because they possess traits which allow them produce more offspring. Evolution isn't focused on producing a "more evolved" species, and species generally aren't focused on being "more evolved." Evolution is "mindless" in the sense that it isn't consciously dictating the evolutionary direction of organisms. Organisms, rather than focusing on evolving, are more focused on survival within their ecological niche.

Hope that helps!
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Re: Okapi, excellent genes and evolution.

Postby 0.0 » Sun Apr 10, 2011 1:03 pm UTC

Bears! wrote:
And could it be a mechanism to leap evolution ahead when it is mostly needed?


This is flawed thinking. Species do not evolve because fitness is "needed" per se. They evolve because they possess traits which allow them produce more offspring. Evolution isn't focused on producing a "more evolved" species, and species generally aren't focused on being "more evolved." Evolution is "mindless" in the sense that it isn't consciously dictating the evolutionary direction of organisms. Organisms, rather than focusing on evolving, are more focused on survival within their ecological niche.

Hope that helps!

No, that doesn't help. I feel like you just told me that gravity isn't the earth trying to hold me close because it cares.
I am aware of the long accepted thoughts on natural selection and the benefits of gene variability. I am simply trying to discuss an undiscussed mechanism. Someone above spoke of a "random sampling" in response to my "elite few survivors" so I am obviously failing to get my point across.

For an example let's just discuss the cheetah and it's sprinting ability. Let's assume that 700,000 years ago, cheetahs had low competition for food, and also had a sprinting speed of an average of 50 mph but with a reasonable standard deviation allowing for 40-60 to be found once in awhile. Imagine a world where there are tens of thousands of cheetah and they reproduce like mad. All sorts of variation going on and population growth is exploding. Now some bad droughts come and the food source dwindles. Now the cheetah is in direct competition with the cheetah. Many of the old prey the cheetah were eating are gone or are hard to find. The only prey left in dependable numbers are the swift beasts that can run a steady 56 mph for longer distances due to its great stamina. The swift beast becomes the only dependable food for cheetah and most starve to death. The cheetah with the legs survive or the cheetah with stamina survive, and maybe the cheetah with the ability to not eat for great stretches survives. Either way the end result is a down selection of a very small number that are still fit to survive in the drastically changed environment. Now the weather gets a little better, water comes back, prey comes back in numbers and the cheetah population booms back from this small number. I understand that this can cause issues from inbreeding if the number is small enough, but I want to talk about the other mechanisms going on, not the ones already well discussed and known. If you think that this would not change the attributes of the big cat, I ask you to look at a miniature poodle. If all dogs died off because of a change in environment, except for the miniature poodle (what advantage it must have is beyond me). You would still be left with dogs (aka Canis lupus familiaris) but there average size would be smaller and the standard deviations of the sizes would have changed. As far as I can tell, a poodle crossed with a poodle gets you a litter of poodle puppies.
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Re: Okapi, excellent genes and evolution.

Postby Pez Dispens3r » Sun Apr 10, 2011 1:30 pm UTC

The problem with cheetahs is that they come from a very small gene pool and there isn't a lot of variance across the entire species to allow for selective pressures to work their magic. They're actually quite a lot closer to the common ancestor of the feline and canine for this reason (lack of retractable claws and a doggish face, yet still more typical of felines in their features and attributes). There was a bottleneck in the past, and although every modern cheetah may be the descendant of a relative few "fittest of the fittest" cheetahs, there wasn't a lot of variation in that pool so they haven't changed much since. That is, that your hypothetical already happened to the cheetah, and what it gave us was a species that hasn't changed much as it feline companions have. (This is a taxonomic illustration of how lonely cheetahs are on their evolutionary branch.)

To whit: where a bottleneck population may evolve rapidly within a small number of generations, their subsequent decedents have little variation to work with and are therefore somewhat vulnerable to environmental changes or predatory and pathological threats.
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Re: Okapi, excellent genes and evolution.

Postby idobox » Sun Apr 10, 2011 2:45 pm UTC

It's probably a question of what is the change in environment.

For example, many species of fish are now significantly smaller than they were 1 century ago, because smaller fish are not caught by nets, and there are regulations on the minimal size of hish that can be caught. So only the smaller x% survive and reproduce.
If the change is more diffuse, and the set of characteristics to survive it is more complex, the evolution will be much slower. For example, with cheetahs, running faster, or longer, or being stronger would be a strong advantage. But it would come at the cost of increased metabolism, so they would need more food.
Selection pressure in this case does not strongly favours super-cheetahs.
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Re: Okapi, excellent genes and evolution.

Postby Pez Dispens3r » Sun Apr 10, 2011 3:31 pm UTC

0.0 wrote:I am aware of the long accepted thoughts on natural selection and the benefits of gene variability. I am simply trying to discuss an undiscussed mechanism.

Belatedly, I might also add that this is the sort of statement that is unlikely to net you any charity. I know you're frustrated with the responses you've received so far, but implying you've found something about an evolutionary mechanism that is "undiscussed" simply tells us you haven't done enough research on the topic. You'd have more luck if you could distill the point you're trying to make, because at the moment it's a little vague, and that the okapi thing is a non sequitor isn't doing you any favours.
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Re: Okapi, excellent genes and evolution.

Postby Izawwlgood » Sun Apr 10, 2011 3:37 pm UTC

The problem with your scenario is it has nothing to do, persay, with bottleneck populations. Animals are always in competition with their neighbors, and 'harshening' of an environment is just another form of natural selection that'd occur anyway. If you're tossing into the mix 'reduction of animal population' than you're just being unclear about whether or not it's sufficiently small for a bottleneck. A bottleneck in and of itself isn't going to make individual competition higher.

It sounds to me like you're assuming a number of variables all at once, and not sure how to separate their different potential affects. d
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Re: Okapi, excellent genes and evolution.

Postby Username4242 » Sun Apr 10, 2011 3:48 pm UTC

I think you really need to read up on genetic drift and bottlenecks. Deleterious alleles can readily become fixed in small populations due to chance alone, in addition to any negative effects of inbreeding, etc. A population of 10 is going to lead pitiful amounts of heterozygosity in the groups' descendants, which in turn means very little "wiggle room" for evolution to work with if conditions change again. Disease outbreaks will also be a huge issue due to great similarities in the organisms' immune systems.

If you want to get a good visual on the effects of this, I highly recommend the program Populous.

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Re: Okapi, excellent genes and evolution.

Postby Turtlewing » Mon Apr 11, 2011 7:51 pm UTC

0.0 wrote: Think about how an entire species dwindles and how that affects the nature of the surviving population. The environment, disease, new competition and lack of easy food are all reasons for decreasing populations. And loss of home by increasing human footprint. all these things push a common focus, and that is increased competition for food, habitat, and reproduction by a single species. Now expand this out over several generations, possibly hundreds or even thousands of years and now the population has dwindled to less than ten. Any one of these specimens would represent the best of the best of that species; Would it not?


No it would not. It would mean that those 10 are the luckiest, not necessarily the best the gene pool had to offer.

If I start with a population of 10,000 lab rats put them in a a big empty cage, then I start shooting them until I only have 10 left. It's not very likely that those 10 are in any way more fit than the others.

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Re: Okapi, excellent genes and evolution.

Postby 0.0 » Mon Apr 11, 2011 11:37 pm UTC

Turtlewing wrote:
0.0 wrote: Think about how an entire species dwindles and how that affects the nature of the surviving population. The environment, disease, new competition and lack of easy food are all reasons for decreasing populations. And loss of home by increasing human footprint. all these things push a common focus, and that is increased competition for food, habitat, and reproduction by a single species. Now expand this out over several generations, possibly hundreds or even thousands of years and now the population has dwindled to less than ten. Any one of these specimens would represent the best of the best of that species; Would it not?


No it would not. It would mean that those 10 are the luckiest, not necessarily the best the gene pool had to offer.

If I start with a population of 10,000 lab rats put them in a a big empty cage, then I start shooting them until I only have 10 left. It's not very likely that those 10 are in any way more fit than the others.


Why would animals in a harsh environment die randomly? Your take on my example is completely wrong.
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Re: Okapi, excellent genes and evolution.

Postby Izawwlgood » Tue Apr 12, 2011 12:09 am UTC

You don't understand what a bottleneck is. What you're actually saying is "If conditions change, shouldn't we expect those species that can adapt, to adapt?" in which case, yes. But that's not a bottleneck.
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Re: Okapi, excellent genes and evolution.

Postby Carnildo » Tue Apr 12, 2011 11:20 am UTC

0.0 wrote:
Turtlewing wrote:
0.0 wrote: Think about how an entire species dwindles and how that affects the nature of the surviving population. The environment, disease, new competition and lack of easy food are all reasons for decreasing populations. And loss of home by increasing human footprint. all these things push a common focus, and that is increased competition for food, habitat, and reproduction by a single species. Now expand this out over several generations, possibly hundreds or even thousands of years and now the population has dwindled to less than ten. Any one of these specimens would represent the best of the best of that species; Would it not?


No it would not. It would mean that those 10 are the luckiest, not necessarily the best the gene pool had to offer.

If I start with a population of 10,000 lab rats put them in a a big empty cage, then I start shooting them until I only have 10 left. It's not very likely that those 10 are in any way more fit than the others.


Why would animals in a harsh environment die randomly? Your take on my example is completely wrong.

He's not killing at random. He's applying a strong selective pressure for "not getting shot". It's highly unlikely that an individual that's good at not getting shot has genes for high disease resistance, or large numbers of viable offspring, or an unusually efficient metabolism, or other versions of "best genes".

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Re: Okapi, excellent genes and evolution.

Postby Turtlewing » Tue Apr 12, 2011 4:08 pm UTC

0.0 wrote:
Turtlewing wrote:
0.0 wrote: Think about how an entire species dwindles and how that affects the nature of the surviving population. The environment, disease, new competition and lack of easy food are all reasons for decreasing populations. And loss of home by increasing human footprint. all these things push a common focus, and that is increased competition for food, habitat, and reproduction by a single species. Now expand this out over several generations, possibly hundreds or even thousands of years and now the population has dwindled to less than ten. Any one of these specimens would represent the best of the best of that species; Would it not?


No it would not. It would mean that those 10 are the luckiest, not necessarily the best the gene pool had to offer.

If I start with a population of 10,000 lab rats put them in a a big empty cage, then I start shooting them until I only have 10 left. It's not very likely that those 10 are in any way more fit than the others.


Why would animals in a harsh environment die randomly? Your take on my example is completely wrong.


No, I'm pointing out that your example is based on a premise that doesn't always hold. You've assumed that the "harsh environment" selects for traits that are beneficial to the species. That's not always true. Sometimes the harsh environment is harsh because it kills randomly and there's nothing the species can do to save itself, or it selects for traits that are detrimental except that they help deal with one potentially temporary selective pressure.

Some examples:
A volcano erupts, those organisms that are too close die.

A new fashion values the pelt of a particular animal. The ones the hunters decide to shoot die (basically the same as my example).

A species that always returns to the same beach to spawn has a hotel built on one of it's spawning beaches. The animals that were spawned from a different beach are fine but the ones that came from that beach can't reproduce anymore.

A species becomes a popular exotic pet. People remove specimens they think will sell well and put them in captivity removing them from the gene pool (this may even result in a case of the species surviving by sacrificing the "best" of it's number).

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Re: Okapi, excellent genes and evolution.

Postby nitePhyyre » Tue Apr 12, 2011 7:19 pm UTC

Turtlewing wrote:A volcano erupts, those organisms that are too close die.

A new fashion values the pelt of a particular animal. The ones the hunters decide to shoot die (basically the same as my example).

A species that always returns to the same beach to spawn has a hotel built on one of it's spawning beaches. The animals that were spawned from a different beach are fine but the ones that came from that beach can't reproduce anymore.

A species becomes a popular exotic pet. People remove specimens they think will sell well and put them in captivity removing them from the gene pool (this may even result in a case of the species surviving by sacrificing the "best" of it's number).

So ok, you can come up with a bunch of convoluted scenarios that cause cataclysmic events in the population of a species. Good job. Did you even bother to read the OP?

0.0 wrote:all these things push a common focus, and that is increased competition for food, habitat, and reproduction by a single species. Now expand this out over several generations, possibly hundreds or even thousands of years
When is the last time you've heard of a volcano eruption lasting thousands of years? Or the last time it took a thousand years to build a bloody beach resort? Or a 1000 year fashion fad?

Yes, the OPs question isn't that clear. But what is very clear is that you didn't even attempt to address it.

@OP:
0.0 wrote:all these things push a common focus, and that is increased competition for food, habitat, and reproduction by a single species. Now expand this out over several generations, possibly hundreds or even thousands of years and now the population has dwindled to less than ten. Any one of these specimens would represent the best of the best of that species; Would it not?
"Best" is a value judgment that evolution doesn't make. It would represent the best of a species at getting food, living in comfortable habitats, and getting laid. Nothing more. It doesn't mean that they will be any better at surviving other conditions or illnesses, nor would it mean they are smarter, or nicer, or another traits that humans typically give value to.

If there is a strong selection for trait x (hunting) then a species will be better at x than if that selection pressure never existed. Kind of a no-brainer.

0.0 wrote:My thought is: If a species like the cheetah dwindles down to a small number, there by rectifying the unbalance between the harshness of its current environment with its natural ability to survive (assuming humans weren't the cause), would it then be able to naturally repopulate just from this sort of super survival of the fittest filter? Has this phenomenon happened before? And could it be a mechanism to leap evolution ahead when it is mostly needed?
Is it possible that a species who has had a bottleneck will be able to repopulate if the selection pressures are lessened, or if the reach an 'equilibrium' with the increase in selection pressure? Yes, humans have done it. Very,very well, I might add. Is it guaranteed? By no means. Again, they are only 'best' at the things they received pressure on. If something else, like a virus, comes their way they have a much, much, MUCH higher chance of being fucked.
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Re: Okapi, excellent genes and evolution.

Postby Sizik » Tue Apr 12, 2011 8:05 pm UTC

nitePhyyre wrote:Or a 1000 year fashion fad?


I hear leather's been in for the past few millennia.
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Re: Okapi, excellent genes and evolution.

Postby Izawwlgood » Tue Apr 12, 2011 8:07 pm UTC

The textile industry is why we have a number of breeds of cattle, sheep, various strains of cotton, silk worms, etc. Sort of the opposite of the example's intent, I think.

The point still stands; the OP has not demonstrated an understanding of what a bottleneck is.
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Re: Okapi, excellent genes and evolution.

Postby Turtlewing » Wed Apr 13, 2011 4:22 pm UTC

nitePhyyre wrote:So ok, you can come up with a bunch of convoluted scenarios that cause cataclysmic events in the population of a species. Good job. Did you even bother to read the OP?


Yes, the OP is asking why a bottleneck event is damaging to a species. There are two reasons for this:

1. (the one I've been pointing out) A bottleneck is when a large percentage of a species population stops reproducing, but the species as a whole doesn't go extinct. That's often a result of some short term catastrophic change in the species' environment (long term changes usually either drive the species extinct, or don't reduce the genetic diversity to the extent necessary to call it a bottleneck). In that case you're survivors aren't going to be the most fit in an evolutionary sence, they will be a more or less random sampling of the pre-bottleneck population. This will not result in a stronger species emerging from the bottleneck than what entered it, because the "selective pressure" isn't favoring members with an advantage that can be passed on to their offspring.

2. (what others have said) A species ability to adapt to environmental change is directly proportionate to it's genetic diversity. A bottleneck by definition reduces genetic diversity, so a species that has survived a bottleneck will by definition be less likely to survive the next environmental change.

When you combine theses you get species going through a bottleneck are: not being optimized for their environment, and are loosing the ability to adapt to future changes. It should be clear that that's not beneficial to the species.

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Re: Okapi, excellent genes and evolution.

Postby Moose Hole » Wed Apr 13, 2011 8:19 pm UTC

0.0, don't listen to these trolls. We can help evolution out by killing off lesser members of species so that only the ones with the best genes are left. I suggest we set up concentration camps and gas chambers for lazy cheetahs.

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Re: Okapi, excellent genes and evolution.

Postby Kayomaro » Thu Apr 14, 2011 2:15 pm UTC

Alrighty then. After reading the entirety of the thread, I think I've come to a decent conclusion.

o.o was asking (and correct me if I'm wrong here) whether or not the surviving members of a species after several hundred years of "harder-than-normal" environmental stress, which caused the population to lower drastically in number, would be the superior members of that species.

My answer is yes. Now before everyone goes all troll on me, let me explain. We all know how evolution works, yes? Well then the answer is simple. The members who survive are best suited to survival, and therefore better at the time that we observe the population as a whole. Now sure some weird disease could come in and wipe the species out, but that's not what we're talking about. The main focus of this thread is to answer whether or not a species is better off (and I use better lightly) after a period of harsh and presumably fast evolution. Once the species recovers, regardless of environmental change afterwards or genetic variability, the surviving members of said species will be better suited to reproduce and thrive in the environment.

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Re: Okapi, excellent genes and evolution.

Postby Izawwlgood » Thu Apr 14, 2011 2:26 pm UTC

Kayomaro wrote:Once the species recovers, regardless of environmental change afterwards or genetic variability, the surviving members of said species will be better suited to reproduce and thrive in the environment.

So, hypothetical here: You've got a population of snails that live in a brine lake. The local area is undergoing a period of dehydration caused by rain forest a mountain range over growing larger and sequestering more water from the air. As the lake slowly evaporates, it becomes saltier. Gradually, say, over a thousand years (reasonably rapidly given evolutionary scales, which is why I picked a fast breeding critter like snails), the salinity of the lake increases, selecting for individuals that are best able to survive in saltier and saltier conditions.

Important thing to remember here: The population of the snails probably won't decline, as fresher water snails die out more rapidly, the salt water loving snails will proliferate more.

Now assume, for shits and giggles, that an earthquake or landslide or river meanders through or whatever happens, and part of the mountain range is bypassed, and now tons of freshwater come pouring into the now salty lake, drastically lowering the salinity in fairly short order (maybe over the course of 100 years). All those snails that love that salt water, yeah, they suddenly aren't so adapted for the lake they're in.

Extrapolate this to your cheetah example; define 'harsher'. Do you mean drier? Hotter? Colder? More diseases? More cheetahs to compete with? You can't simply say "harsher conditions make tougher cheetahs, so when things get less harsh, they'll totally rock face!" because that's not how evolution works.
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Re: Okapi, excellent genes and evolution.

Postby qetzal » Thu Apr 14, 2011 3:26 pm UTC

Kayomaro wrote:Alrighty then. After reading the entirety of the thread, I think I've come to a decent conclusion.

o.o was asking (and correct me if I'm wrong here) whether or not the surviving members of a species after several hundred years of "harder-than-normal" environmental stress, which caused the population to lower drastically in number, would be the superior members of that species.

My answer is yes. Now before everyone goes all troll on me, let me explain. We all know how evolution works, yes? Well then the answer is simple. The members who survive are best suited to survival, and therefore better at the time that we observe the population as a whole. Now sure some weird disease could come in and wipe the species out, but that's not what we're talking about. The main focus of this thread is to answer whether or not a species is better off (and I use better lightly) after a period of harsh and presumably fast evolution. Once the species recovers, regardless of environmental change afterwards or genetic variability, the surviving members of said species will be better suited to reproduce and thrive in the environment.


No. Think again about the scenario. Some extreme selective pressure drives a species down to a relatively few individuals. Those individuals may well be better adapted to surviving under that extreme pressure. But then this extreme selective pressure is relaxed somehow, allowing the population to rebound. By definition, the environment has changed. Those individuals that were highly adapted to surviving & reproducing under the extreme selective pressure now have to survive and reproduce in a different environment with different selective pressures. The adaptations that were 'best' before might actually be deleterious in the new environment. At minimum, they're no longer especially critical for survival. (Again, by definition.)

A new environment means new adaptations are likely to be favored. But because of the bottleneck, there is much less genetic diversity in the population. That means less possibility that new combinations of existing alleles will prove advantageous under the new conditions. Even if the environment returns to the state it was in prior to the extreme selection, there's no guarantee that these individuals are now more fit to survive than the average pre-bottleneck individual. After all, if the new adaptations are advantageous under the old environmental conditions, they would have been under positive selection before the bottleneck. Perhaps a bottleneck would fix them faster, but I don't see why that's a good thing, and the loss of genetic diversity in unrelated traits is almost guaranteed to be a bad thing.

nitePhyyre
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Re: Okapi, excellent genes and evolution.

Postby nitePhyyre » Thu Apr 14, 2011 3:57 pm UTC

tl;dr
It depends?
sourmìlk wrote:Monopolies are not when a single company controls the market for a single product.

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rickd
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Re: Okapi, excellent genes and evolution.

Postby rickd » Fri Apr 15, 2011 12:20 am UTC

If the environment exerts a strong selection pressure for trait X, then the remaining members of a species are highly likely to exhibit trait X. But this doesn't mean that they're 'superior' in any way, only that they are more suited to an trait X-friendly environment.
If the environment then changes to favor trait Y instead, then a species with few members would have difficulty surviving, unless trait X is strongly correlated with trait Y. So yes, it depends.


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