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On June 03 2017 09:12 Sent. wrote:Here's the answer. Show nested quote +Fisher’s principle explains why for most species, the sex ratio is approximately 1:1. Bill Hamilton expounded Fisher’s argument in his 1967 paper on “Extraordinary sex ratios”[1] as follows, given the assumption of equal parental expenditure on offspring of both sexes.
1. Suppose male births are less common than female.
2. A newborn male then has better mating prospects than a newborn female, and therefore can expect to have more offspring.
3. Therefore parents genetically disposed to produce males tend to have more than average numbers of grandchildren born to them.
4. Therefore the genes for male-producing tendencies spread, and male births become more common.
5. As the 1:1 sex ratio is approached, the advantage associated with producing males dies away.
6. The same reasoning holds if females are substituted for males throughout. Therefore 1:1 is the equilibrium ratio.
In modern language, the 1:1 ratio is the evolutionarily stable strategy (ESS).[10] This ratio has been observed in many species, including the bee Macrotera portalis. A study performed by Danforth observed no significant difference in the number of males and females from the 1:1 sex ratio.[11]
This doesn't really explain the why. If males are more likely to die before they reproduce, then point 3 isn't true at all. I mean, I'm sure he's right, because Fisher was a genius. But it's not trivially so. What follows from the argument is that necessarily,
E(#grandchildren|male)*p(male) = E(#grandchildren|female)*(1 -p(male)/
However, there's no real reason why the expected number of grandchildren given a male child should equal that for a female child.
E: thanks for the idea for a great netlogo assignment!
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On June 03 2017 16:41 Simberto wrote:Show nested quote +On June 03 2017 16:24 Cascade wrote:On June 03 2017 11:58 Uldridge wrote:
But think about this: "genes" for spreading male-producing tendencies makes no sense, because the chances of being male or female stays 50% you won't have xy sperm that suddenly swims 10% faster than the xx sperm, because that's what the only difference between both is. You'd need to have an unevenness in structure of the different sexed sperm. Where all the difference would need to be between an x and y chromosome. More men just don't magically appear like that. If it were evolutionary selected for to have babies at 1.5:1 ratio, I'm sure there are plenty of ways nature could make that happen. Indeed. Once again, weird bugs that grow up in their mothers. They always have 1 male and 3-8 pregnant females be born from one mother. Not random amounts of males and females. So it obviously is possible to not have 1:1 ratios. But the above evolutionary argument makes sense. I was looking at it from a species perspective, not from an individual one.
And then there is the cell level evolution as well. It's interesting how they all interact and affect the DNA sequence.
On June 03 2017 17:06 Acrofales wrote:Show nested quote +On June 03 2017 09:12 Sent. wrote:Here's the answer. Fisher’s principle explains why for most species, the sex ratio is approximately 1:1. Bill Hamilton expounded Fisher’s argument in his 1967 paper on “Extraordinary sex ratios”[1] as follows, given the assumption of equal parental expenditure on offspring of both sexes.
1. Suppose male births are less common than female.
2. A newborn male then has better mating prospects than a newborn female, and therefore can expect to have more offspring.
3. Therefore parents genetically disposed to produce males tend to have more than average numbers of grandchildren born to them.
4. Therefore the genes for male-producing tendencies spread, and male births become more common.
5. As the 1:1 sex ratio is approached, the advantage associated with producing males dies away.
6. The same reasoning holds if females are substituted for males throughout. Therefore 1:1 is the equilibrium ratio.
In modern language, the 1:1 ratio is the evolutionarily stable strategy (ESS).[10] This ratio has been observed in many species, including the bee Macrotera portalis. A study performed by Danforth observed no significant difference in the number of males and females from the 1:1 sex ratio.[11] This doesn't really explain the why. If males are more likely to die before they reproduce, then point 3 isn't true at all. I mean, I'm sure he's right, because Fisher was a genius. But it's not trivially so. What follows from the argument is that necessarily, E(#grandchildren|male)*p(male) = E(#grandchildren|female)*(1 -p(male)/ However, there's no real reason why the expected number of grandchildren given a male child should equal that for a female child. E: thanks for the idea for a great netlogo assignment!
If half of the males die, but the female live, then the males get to bang twice as many ladies as the other way around on average.
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that argument does not make sense as far as humans or any species that has a low new generation/time ratio(they breed slow, really slow) go. also, it doesn't account for environmental factors/stresses. (the @Sent. one)
let's say a population is recovering from a lack of males and we get to 3) ...parents genetically disposed to produce males.
now, here comes the environmental stress and kills 90% of the females. with most of the females dead and the population having a predisposition to birthing males, they're fucked(...pending breeding rates).
for a species that breeds often and in large amounts, that would not be that much of a big deal but for the slow breeders, one offspring at 20 to 50 years, that's the end of the line.
even when we assume that some survive and get to a balanced population(1:1, albeit smaller) again, you have interbreeding to deal with. evolution doubles down on them.
any explanation to 1:1 that wants to be taken seriously needs to account for space and speed.
space as in, their geographical(living) sphere(because there's no way the chinese are under the same breeding stress as the germans) and speed as in, their ability to correct huge fluctuations in (sex)numbers across very few generations, if not immediately.
you're still left here with the actual mechanic of it: can evolution count dicks and/or vaginas?.
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On June 03 2017 17:39 xM(Z wrote:
that argument does not make sense as far as humans or any species that has a low new generation/time ratio(they breed slow, really slow) go. also, it doesn't account for environmental factors/stresses. (the @Sent. one)
let's say a population is recovering from a lack of males and we get to 3) ...parents genetically disposed to produce males.
now, here comes the environmental stress and kills 90% of the females. with most of the females dead and the population having a predisposition to birthing males, they're fucked(...pending breeding rates).
for a species that breeds often and in large amounts, that would not be that much of a big deal but for the slow breeders, one offspring at 20 to 50 years, that's the end of the line.
even when we assume that some survive and get to a balanced population(1:1, albeit smaller) again, you have interbreeding to deal with. evolution doubles down on them.
any explanation to 1:1 that wants to be taken seriously needs to account for space and speed.
space as in, their geographical(living) sphere(because there's no way the chinese are under the same breeding stress as the germans) and speed as in, their ability to correct huge fluctuations in (sex)numbers across very few generations, if not immediately.
you're still left here with the actual mechanic of it: can evolution count dicks and/or vaginas?.
Evolution can obviously count dicks and vaginas at a genetic level. Can have a process that selectively kills sperm cells with an X or Y chromosome. Or a process that aborts zygotes with XX or XY. It seems like it would be a fairly straightforward adaptation. Whether it can happen? Hard to know.
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We are talking about evolution. Evolution means time scales of millions of years. The argument works, because it is not based on a single event killing 90% of all males, but on an equilibrium that favors more males being born.
On an evolutionary scale, chinese and westerners are under the same breeding stress, because they are the same species. History is basically irrelevant to evolution, because all of history happened in the last 5000-10000 years. That is not evolutionary time. Evolution happens over hundreds of thousands of years.
Edit: Also, evolution can obviously not count dicks. Evolution is not sentient. It is a process. What can happen, however, is that it turns out that in a given situation, producing more males can leads to an increased change of having more offspring. For example, if there are a shitload of females around, but basically not males. In that case, those who produce more males will produce more offspring. It is utterly irrelevant how fast the reproduction cycle is, as long as there is a stable equilibrium situation. Evolution happens when that stable equilibrium slowly shifts over time due to every species slowly changing to adapt better to the current situation, which shifts the equilibrium slightly, which leads to a slightly different situation to adapt to for everyone else.
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We are talking about evolution. Evolution means time scales of millions of years. that doesn't even exist as an afterthought let alone an argument for the 1:1 thing.
if you spend millions of years getting to that 1:1, then during all those millions of years you were not at 1:1. so how can you justify it(the 1:1)as the ratio when you spend millions of years not in it?.
For example, if there are a shitload of females around, but basically not males. In that case, those who produce more males will produce more offspring. that is also biologically false. a single male can produce millions of offspring; that in itself makes the nr. of males totally irrelevant.
Edit: and sorry but On an evolutionary scale, chinese and westerners are under the same breeding stress, because they are the same species is just ignorant. the stress comes from the environment not from "the specie".
the chinese have preferential/sex-based abortions; if you tell me that's also the case in Germany i'll kick you off EU myself.
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If 1:1 was the initial ratio then you can assume that genetically it's the default state and it will not change unless subjected to a strong and very long-lasting factor, which is unlikely. We can't evolve out of 1:1 because we don't have anything that gives one sex a "permanent" edge in reproduction.
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On June 03 2017 17:39 xM(Z wrote:
that argument does not make sense as far as humans or any species that has a low new generation/time ratio(they breed slow, really slow) go. also, it doesn't account for environmental factors/stresses. (the @Sent. one)
let's say a population is recovering from a lack of males and we get to 3) ...parents genetically disposed to produce males.
now, here comes the environmental stress and kills 90% of the females. with most of the females dead and the population having a predisposition to birthing males, they're fucked(...pending breeding rates).
for a species that breeds often and in large amounts, that would not be that much of a big deal but for the slow breeders, one offspring at 20 to 50 years, that's the end of the line.
even when we assume that some survive and get to a balanced population(1:1, albeit smaller) again, you have interbreeding to deal with. evolution doubles down on them.
any explanation to 1:1 that wants to be taken seriously needs to account for space and speed.
space as in, their geographical(living) sphere(because there's no way the chinese are under the same breeding stress as the germans) and speed as in, their ability to correct huge fluctuations in (sex)numbers across very few generations, if not immediately.
you're still left here with the actual mechanic of it: can evolution count dicks and/or vaginas?.
If what Fisher says doesn't make sense to you, it is usually a good idea to approach it with a "did I miss something?" kind of angle.
The statement isn't about a situation where the population is male of female biased due to environmental factors. A single event that kills 90% of the females will be fully corrected in one generation in a 1:1 species. As it says in point 1, It's a thought experiment of a non 1:1 species.
Maybe you meant a situation where long term conditions triggered a 10:1 species (in some way), and then suddenly conditions change and suddenly a 1:10 is favourable? Then yes, the species will struggle, as will any species when you drastically change the condition. See the coral reef as example of that.
I have no idea what you mean with the last question. I'm not even sure if it's rhetorical or not. Answering the question at face value, which may not be what you wanted (sorry): the actual mechanic is that DNA that produce 1:1 offspring is better at copying itself than DNA that doesn't, under these assumptions. No one is counting genitals.
On June 03 2017 19:44 Sent. wrote:
If 1:1 was the initial ratio then you can assume that genetically it's the default state and it will not change unless subjected to a strong and very long-lasting factor, which is unlikely. We can't evolve out of 1:1 because we don't have anything that gives one sex a "permanent" edge in reproduction.
Yeah, evolution is such a rigid thing. Only very few way in which it can change. Perfectly well understood as well. Everyone knows exactly what a cell can and can't do, so an organism like a human is just a simple matter of extrapolating that knowledge to a larger system. That's what we have computers for, right?
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On June 03 2017 19:09 xM(Z wrote:Show nested quote +We are talking about evolution. Evolution means time scales of millions of years. that doesn't even exist as an afterthought let alone an argument for the 1:1 thing. if you spend millions of years getting to that 1:1, then during all those millions of years you were not at 1:1. so how can you justify it(the 1:1)as the ratio when you spend millions of years not in it?. Show nested quote +For example, if there are a shitload of females around, but basically not males. In that case, those who produce more males will produce more offspring. that is also biologically false. a single male can produce millions of offspring; that in itself makes the nr. of males totally irrelevant. Edit: and sorry but Show nested quote +On an evolutionary scale, chinese and westerners are under the same breeding stress, because they are the same species is just ignorant. the stress comes from the environment not from "the specie". the chinese have preferential/sex-based abortions ; if you tell me that's also the case in Germany i'll kick you off EU myself.
Anything that has happened in the last 500 years is utterly irrelevant from an evolutionary point of view. Evolution simply works on much larger timeframes. Thus, what happens in Germany or in China is not relevant to evolution, which is what we were talking about.
Evolution is about long term development of species, not about short term stuff.
And the point is that if evolution constantly pushes you towards a 1:1 ratio between sexes, that means that you are never far off from that ratio. Because if you ever stray a bit from that equilibrium, it becomes increasingly harmful for your genes to stray further away from it, and increasingly beneficial for for your genes to move back towards the equilibrium.
I would highly suggest that you try to understand how equilibrium states work, the fun thing is that they work pretty much exactly the same, no matter if you talk about physics, biology, chemistry, or anything else. If you understand how things behave close to a stable equilibrium, you understand a lot of things better. You currently may believe that you understand it, but you really don't.
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has nothing to do with how "equilibrium states work"; i just don't buy your time frame.
if your randomly chosen time frame is measured in millions then good luck finding someone who cares.
- is it 1:1 now?. nope.
- will it get to 1:1 in my foreseeable future?. people/me are pondering on it and you don't know, but have faith it will because ... it what evolution(equilibrium) does apparently.
- will it get to 1:1 in millions of years?. people/me don't care because <calamities and aliens> but you're sure because equilibrium happens eventually.
you can't get more than to each their own there. there is equilibria happening on a much smaller time frame than your millions so your random and apparently only one worth considering time frame for that 1:1, is not accepted.
i want to talk about 1:1 in let's say ... 3 generations.
equilibrium states don't just work; they're(two or more states) forced to work until equilibrium happens.
why is the equilibrium between males and females 1:1?. why not 1:3 or 5:2?. why is 1 female = 1 male(in physics)?.
equilibrium doesn't mean equal, it means the same value(uniform) as a measure of (final/resulting)energy value.
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Evolution does not "improve" the species, it is what happens when a species is able to survive from its selection process.
It makes no sense that bugs have to eat their own mothers alive--but reproduction is not meant to be efficient.
Most bugs and lizards have the environment dictate their sex, hence the ratio changes. For species where sex is chosen genetically at a 50/50 ratio, then it will produce 1:1 sex ratios until a strong enough variable forces it to change.
Bugs literally change sexes back and forth as needed. So it's not as simple as "evolution will blah blah"
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On June 03 2017 22:00 xM(Z wrote:
has nothing to do with how "equilibrium states work"; i just don't buy your time frame.
if your randomly chosen time frame is measured in millions then good luck finding someone who cares.
- is it 1:1 now?. nope.
- will it get to 1:1 in my foreseeable future?. people/me are pondering on it and you don't know, but have faith it will because ... it what evolution(equilibrium) does apparently.
- will it get to 1:1 in millions of years?. people/me don't care because <calamities and aliens> but you're sure because equilibrium happens eventually.
you can't get more than to each their own there. there is equilibria happening on a much smaller time frame than your millions so your random and apparently only one worth considering time frame for that 1:1, is not accepted.
i want to talk about 1:1 in let's say ... 3 generations.
equilibrium states don't just work; they're(two or more states) forced to work until equilibrium happens.
why is the equilibrium between males and females 1:1?. why not 1:3 or 5:2?. why is 1 female = 1 male(in physics)?.
equilibrium doesn't mean equal, it means the same value(uniform) as a measure of (final/resulting)energy value.
Not sure if you are trolling (sorry if you're not), so I'll make this short. The points from Fisher has everything to do with equilibrium. The entire thing is a an argument why deviation from 1:1 will produce an evolutionary force back towards 1:1. Which then indicates that 1:1 is a stable equilibrium.
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On June 03 2017 22:14 Thieving Magpie wrote:
Evolution does not "improve" the species, it is what happens when a species is able to survive from its selection process.
It makes no sense that bugs have to eat their own mothers alive--but reproduction is not meant to be efficient.
Most bugs and lizards have the environment dictate their sex, hence the ratio changes. For species where sex is chosen genetically at a 50/50 ratio, then it will produce 1:1 sex ratios until a strong enough variable forces it to change.
Bugs literally change sexes back and forth as needed. So it's not as simple as "evolution will blah blah"
Evolution and survival of the fittest go hand in hand. 'better' genes will reproduce more thereby 'improving' a species. That doesn't mean that everything has to make sense (tho I would bet if you studied why bugs eat their mother you find a reason for it being "better").
Evoultion sometimes goes a wrong way and does something negative but overall I would certainly say it 'improves' species.
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On June 03 2017 22:25 Gorsameth wrote:Show nested quote +On June 03 2017 22:14 Thieving Magpie wrote:
Evolution does not "improve" the species, it is what happens when a species is able to survive from its selection process.
It makes no sense that bugs have to eat their own mothers alive--but reproduction is not meant to be efficient.
Most bugs and lizards have the environment dictate their sex, hence the ratio changes. For species where sex is chosen genetically at a 50/50 ratio, then it will produce 1:1 sex ratios until a strong enough variable forces it to change.
Bugs literally change sexes back and forth as needed. So it's not as simple as "evolution will blah blah" Evolution and survival of the fittest go hand in hand. 'better' genes will reproduce more thereby 'improving' a species. That doesn't mean that everything has to make sense (tho I would bet if you studied why bugs eat their mother you find a reason for it being "better"). Evoultion sometimes goes a wrong way and does something negative but overall I would certainly say it 'improves' species.
Evolution is not a moralistic or qualitative dictum. It's simply the observed patterns of things that found a way to not die out; to believe it is deterministic to improvement is folly.
The only thing Evolution tells us is what that species preferred.
As an example; giraffes got long necks because eating tall trees was what they preferred. Eating tall trees is not "better" than eating short ones, and eating tree leaves is not "better" than eating non-tree leaves. How much "better" it is for the giraff/ecosystem/etc is meaningless. It's simply that, over time, their sexual preferences/survival patterns lead to favoring longer necks than shorter ones.
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Also, for a small, but important nitpick: evolution doesn't necessarily take place over millions of years. It depends on the organism and the propagation method. Selective breeding can cause very rapid speciation, which can in turn cause for a new species to emerge faster. Obviously bacteria evolve at a much faster rate than humans.
Evolution oftenly is presented with littme nuance. Survival of the fittest simply means that certain individual has the genetic/physiological toolset to survive the (new/arisen) environment. This does not mean it's inherently better. It means that it (still) works. The reason you can still see all these different species that are very similar to what they used to be -evolutionarily speaking, even though genetic drift keeps happening over those millions of years- is because their niche (which is related to habitat) is so well chosen, that they don't need adaptation. I'm sure that most diversification comes from a population being too succesful, it needs to find a new habitat/niche or certain individuals would die out.
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On June 04 2017 00:58 Uldridge wrote:
Also, for a small, but important nitpick: evolution doesn't necessarily take place over millions of years. It depends on the organism and the propagation method. Selective breeding can cause very rapid speciation, which can in turn cause for a new species to emerge faster. Obviously bacteria evolve at a much faster rate than humans.
Evolution oftenly is presented with littme nuance. Survival of the fittest simply means that certain individual has the genetic/physiological toolset to survive the (new/arisen) environment. This does not mean it's inherently better. It means that it (still) works. The reason you can still see all these different species that are very similar to what they used to be -evolutionarily speaking, even though genetic drift keeps happening over those millions of years- is because their niche (which is related to habitat) is so well chosen, that they don't need adaptation. I'm sure that most diversification comes from a population being too succesful, it needs to find a new habitat/niche or certain individuals would die out.
Natural Selection also doesn't self correct or self-Progress. If the propagation method does not make the species extinct then it will simply continue that propagation method until outside variables prevent it from doing so--even if it's cannibalising your mother from the inside out.
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On June 03 2017 22:24 Cascade wrote:Show nested quote +On June 03 2017 22:00 xM(Z wrote:
has nothing to do with how "equilibrium states work"; i just don't buy your time frame.
if your randomly chosen time frame is measured in millions then good luck finding someone who cares.
- is it 1:1 now?. nope.
- will it get to 1:1 in my foreseeable future?. people/me are pondering on it and you don't know, but have faith it will because ... it what evolution(equilibrium) does apparently.
- will it get to 1:1 in millions of years?. people/me don't care because <calamities and aliens> but you're sure because equilibrium happens eventually.
you can't get more than to each their own there. there is equilibria happening on a much smaller time frame than your millions so your random and apparently only one worth considering time frame for that 1:1, is not accepted.
i want to talk about 1:1 in let's say ... 3 generations.
equilibrium states don't just work; they're(two or more states) forced to work until equilibrium happens.
why is the equilibrium between males and females 1:1?. why not 1:3 or 5:2?. why is 1 female = 1 male(in physics)?.
equilibrium doesn't mean equal, it means the same value(uniform) as a measure of (final/resulting)energy value. Not sure if you are trolling (sorry if you're not), so I'll make this short. The points from Fisher has everything to do with equilibrium. The entire thing is a an argument why deviation from 1:1 will produce an evolutionary force back towards 1:1. Which then indicates that 1:1 is a stable equilibrium. but it is known that his theory is at least incomplete since it only takes into account natural selection while ignoring the external factors or other factors that could be involved in gene frequency changes.
it's a thing that works in a vacuum while ignoring 50% of the triggers for gene changes.
Edit: basically covariance, quantitative genetics/polygenic variation or seemingly same environmental effects triggering different phenotypic states on a per individual basis and godknowshowmanymorethings.
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On June 04 2017 01:07 Thieving Magpie wrote:Show nested quote +On June 04 2017 00:58 Uldridge wrote:
Also, for a small, but important nitpick: evolution doesn't necessarily take place over millions of years. It depends on the organism and the propagation method. Selective breeding can cause very rapid speciation, which can in turn cause for a new species to emerge faster. Obviously bacteria evolve at a much faster rate than humans.
Evolution oftenly is presented with littme nuance. Survival of the fittest simply means that certain individual has the genetic/physiological toolset to survive the (new/arisen) environment. This does not mean it's inherently better. It means that it (still) works. The reason you can still see all these different species that are very similar to what they used to be -evolutionarily speaking, even though genetic drift keeps happening over those millions of years- is because their niche (which is related to habitat) is so well chosen, that they don't need adaptation. I'm sure that most diversification comes from a population being too succesful, it needs to find a new habitat/niche or certain individuals would die out. Natural Selection also doesn't self correct or self-Progress. If the propagation method does not make the species extinct then it will simply continue that propagation method until outside variables prevent it from doing so--even if it's cannibalising your mother from the inside out. that part could be argued upon.
i'm leaning towards at least self-efficientization(fr) if not some self-feedback of sorts. random and survival do not explain some things.
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On June 04 2017 01:16 xM(Z wrote:Show nested quote +On June 03 2017 22:24 Cascade wrote:On June 03 2017 22:00 xM(Z wrote:
has nothing to do with how "equilibrium states work"; i just don't buy your time frame.
if your randomly chosen time frame is measured in millions then good luck finding someone who cares.
- is it 1:1 now?. nope.
- will it get to 1:1 in my foreseeable future?. people/me are pondering on it and you don't know, but have faith it will because ... it what evolution(equilibrium) does apparently.
- will it get to 1:1 in millions of years?. people/me don't care because <calamities and aliens> but you're sure because equilibrium happens eventually.
you can't get more than to each their own there. there is equilibria happening on a much smaller time frame than your millions so your random and apparently only one worth considering time frame for that 1:1, is not accepted.
i want to talk about 1:1 in let's say ... 3 generations.
equilibrium states don't just work; they're(two or more states) forced to work until equilibrium happens.
why is the equilibrium between males and females 1:1?. why not 1:3 or 5:2?. why is 1 female = 1 male(in physics)?.
equilibrium doesn't mean equal, it means the same value(uniform) as a measure of (final/resulting)energy value. Not sure if you are trolling (sorry if you're not), so I'll make this short. The points from Fisher has everything to do with equilibrium. The entire thing is a an argument why deviation from 1:1 will produce an evolutionary force back towards 1:1. Which then indicates that 1:1 is a stable equilibrium. but it is known that his theory is at least incomplete since it only takes into account natural selection while ignoring the external factors or other factors that could be involved in gene frequency changes. it's a thing that works in a vacuum while ignoring 50% of the triggers for gene changes. Edit: basically covariance, quantitative genetics/polygenic variation or seemingly same environmental effects triggering different phenotypic states on a per individual basis and godknowshowmanymorethings.
Not all species are 1:1, so it's clear it's not the entire truth. The argument doesn't explicitly mention external factors, but it doesn't depend on it. External factors just don't matter for the argument. This drive towards 1:1 is always there, only that sometimes there are stronger drivers away from it.
And I have no idea what your edit is supposed to mean. Seems like just a list of random genetics buzzwords. I mean... If it's not a troll, maybe you can go through that list of words and explain how they are relevant? Quantitative genetics? Polygenic varition? I mean.... What? How is that relevant? >_> Are you trying to sounds smart by using random buzzwords? I really don't get this.
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EPT
