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Another God
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This question isn't as obvious as it first seems. Think about it a bit: Why do we have 2 sexes?
Having 3 sexes doesn't mean u require 3 individuals to participate in reproduction. It just means that sex a can mate with eitehr sex B or sex C. Actually giving each individual more options.Originally posted by FZ+
Because additional sexes will be too complicated, requiring the action of several individuals that is too unreliable and brings too little a benefit.
You don't need sexes for gene swapping and recombination. You can have asexual mating.
Because two sexes allow more capability for adaptation than one.
Why should be more necessary? 2 is enough and it does the jobOriginally posted by Another God
Why do we have 2 sexes?
Gene swapping is not so easy and efficient for many metazoan.Originally posted by Another God
You don't need sexes for gene swapping and recombination. You can have asexual mating.
It's not necessarily a good thing to have both partners tied up with a pregnancy, which consumes more resources, often makes one more vulnerable, etc. (I also don't agree that "twice as efficient" is "astronomical" in evolutionary terms, even accepting that it is "more efficient" at all.) And sexual dimorphism can be useful: it in effect turns one species into two specialized, cooperating subspecies.It would be twice as efficient (and twice as efficient in evolutionary terms is astronomical) if individuals could mate with anyone, and for every mating event, they literally swapped gametes with each other, getting both of them 'pregnant' (in whatever form that may be).
I don't understand how it is either unproductive or how evolution is harder. What do u mean exactly by asexual mating? I mean any process whereby two diploids form haploid cells internally, then swap those haploids to form new recombined diploids... Exactly the same as sexual reproduction, but without the need to match up in an exclusive pairing system. there isn't even any need for different sexual organs.Originally posted by Innexplicable
Asexual mating is unproductive beacuase adaptation, and evolution is harder
Why is that? Evolution still works as normal. 'Sexual Selection' would also still exist, but it wouldn't be male selecting females or females selecting males, it would be a population wide selection from inside. Only the most attractive individuals get mated with. Same concept, less exclusivity.also the possibility to grow larger is neerly impossible.
Natural Selection takes place with one sex, two sexes, or 42 sexes. Natural Selection even takes places where there is no genetic exchange. I don't get this point either.
Having two sexes allows for natural selection to take place, selecting the best genes, and it also lets us evolve fast in certain situations like in a bottleneck effect. Having 1 sex, carrying both sexual organs (the egg and the sperm) would be illogical, since one most have the best trait of any one sex. Some species however have the best traits of one sex, and have the other one on standby incase there are a depleted amount of males or females.
Bacterial and archea still exist and are present in some extreme enviroment. Talk about evolution problem.Originally posted by Innexplicable
Asexual mating is unproductive beacuase adaptation, and evolution is harder
Is the advantage outweigthing the cost in term of evolution. I think so.Originally posted by Another God
The cost of sex is incredibly large if you think about it. In an evolutionary sense, to have two sexes, you need to have two individuals survive to reproductive age, eating x amount of food each etc, just so that one of them can have offspring.
I will answer by thisOriginally posted by Another God
It would be twice as efficient (and twice as efficient in evolutionary terms is astronomical) if individuals could mate with anyone, and for every mating event, they literally swapped gametes with each other, getting both of them 'pregnant' (in whatever form that may be).
Twice as efficient but could cost more than twice as muchOriginally posted by Another God
Each species' biggest threat comes from its own species since they are all competing for exactly the same resources.
I'm not thinking in terms of humans.Originally posted by Another God First thing to do, is to stop thinking in terms of humans.
I didn't say anything about requiring care from parents, either.Take it back to the begining, back when 'pregnancy' didn't really exist. Think of creatures who form a zygote, and then the zygote grows of its own accord, free from requiring care from the parents.
Any way you cut it, reproduction has a cost in one way or another; you don't get offspring for free. If you did, everything would reproduce all the time. (Sure, that that kind of growth couldn't be sustained, but so what, if reproducing doesn't cost anything?)Plenty of organisms can do this, so an argument claiming that too much effort is required if both organisms are 'pregnant' or both will need to take care of young isn't such a good argument.
Having the ability to have more offspring is not necessarily a good thing. Take it to the logical conclusion: why aren't all organisms designed to have thousands of offspring, like insects? It doesn't work well for everybody.So a situation where one species has the ability to have twice as many offspring as a competing species is literally astronomical.
That doesn't follow. If it did, then a species would always wipe itself out before predators could. Moreover, it ignores the existence of cooperation within species.(Each species' biggest threat comes from its own species since they are all competing for exactly the same resources.
So asexual mating already includes meiosis.I don't understand how it is either unproductive or how evolution is harder. What do u mean exactly by asexual mating? I mean any process whereby two diploids form haploid cells internally, then swap those haploids to form new recombined diploids... Exactly the same as sexual reproduction, but without the need to match up in an exclusive pairing system.
I don't understand how it could cost twice as much.Twice as efficient but could cost more than twice as much
There are still species that are hermaphrodite. Best example are snails. How good is there genetics diversity?
Also if you could mate with everyone could that create problem.
I'll say this a few more times, because no one seems to have caught onto it yet: You don't need to have two sexes in order for meiosis => recombination to occur.Originally posted by selfAdjoint
And we need to shuffle to keep up with the bacteria and viruses that infect us in speed of hereitary change.
Things do try to reproduce as much as they can but don't they? It still depends on mating rituals, mate selection (is that other individual good enough for me or not? Will my offspring survive after I invest whatever I invest into them? etc) Every organism does want to have as many offspring as possible, but it also doesn't want to waste its own time/effort/life in doing so.Originally posted by Ambitwistor
Any way you cut it, reproduction has a cost in one way or another; you don't get offspring for free. If you did, everything would reproduce all the time. (Sure, that that kind of growth couldn't be sustained, but so what, if reproducing doesn't cost anything?)
I know that, but being able to produce offspring in times of hardship is advantageous over not being able to. Of course over population could be a problem, but there are other mechanism that ahve evolved to stop that: But this doesn't change the fact that being able to reproduce in harder circumstances, is better than not being able to. That is what evolution works on...the adaptability and ability to continue reproducing no matter how hard the times are...
Having the ability to have more offspring is not necessarily a good thing. Take it to the logical conclusion: why aren't all organisms designed to have thousands of offspring, like insects? It doesn't work well for everybody.
Isn't that my point? Organisms don't actually reproduce as much as possible, because there are costs involved in doing so. In fact, it may be advantageous to have half the population incur different costs than the other half.Originally posted by Another God
Things do try to reproduce as much as they can but don't they? It still depends on mating rituals, mate selection (is that other individual good enough for me or not? Will my offspring survive after I invest whatever I invest into them? etc) Every organism does want to have as many offspring as possible, but it also doesn't want to waste its own time/effort/life in doing so.
Who said anything about not being able to produce offspring? When two organisms (successfully) mate, offspring are produced, regardless of whether the offspring physically come from one of them or both of them.I know that, but being able to produce offspring in times of hardship is advantageous over not being able to.
It wouldn't. But even if he could reproduce asexually as well as sexually, I wouldn't give good odds of the race surviving anyway, if conditions were so harsh that it was already narrowed down to one remaining organism, especially when all you're doing is perpetually producing genetically identical copies (other than the occasional mutation) of that one organism.How often have you heard the saying "I wouldn't have sex with you if you were the last man on earth"? Well, what if there was one man left on earth? How would the race continue to reproduce?
Hermaphrodites have both sexual organs. i.e. it is a male and female at the same time. some species are capable of self-fertilization whereas some requires 2 individuals. Therefore, both partner becomes pregnant.Originally posted by Another God
Hermaphrodites change from male to female right?
So limiting the number of individuals that becomes pregnant, limits the number of new individuals and it limits the competition.Originally posted by Another God
Each species' biggest threat comes from its own species since they are all competing for exactly the same resources.
In term of generation, it takes about the same time for microorganism to adapt to the enviromnent than us. It is just that micororganism take 10 minutes to few hours to have a generation whereas most meazoan take weeks to years. The mutation rate in bacteria and archea is sligthly higher than eucarya. 10-4 to 10-7 for bacteria and archeae and 10-8 to 10-12 for eucarya.Originally posted by Monique
The reason that microorganisms don't need meiosis (in my opinion) is that they divide very very fast and are able to adapt to their environment much quicker than mammals do. They can take up genes from their environment and loose genes when they don't need them.
Have you ever wonder why only mamals have this chromosome dependent sex determination?Originally posted by Another God
Have you ever wondered why the Y chromosome is so much smaller than the X chromosome?
I think this is a good point...its got me thinking....Originally posted by Ambitwistor
Isn't that my point? Organisms don't actually reproduce as much as possible, because there are costs involved in doing so. In fact, it may be advantageous to have half the population incur different costs than the other half.
But even if he could reproduce asexually as well as sexually, I wouldn't give good odds of the race surviving anyway, if conditions were so harsh that it was already narrowed down to one remaining organism, especially when all you're doing is perpetually producing genetically identical copies (other than the occasional mutation) of that one organism
In other words, I am not talking about self fertilisation, or about budding, or cloning. I am talking about sexual redproduction, without needing two exclusive sexes.I'll say this a few more times, because no one seems to have caught onto it yet: You don't need to have two sexes in order for meiosis => recombination to occur.
Sexual reproduction can be done without need of two exclusive sexes. Why are 2 sexes so predominant?
I am not talking about hermaphrodites, I am talking about there being no sexes. There would still be sexual reproduction.Originally posted by iansmith
Genetic diversity becomes important. If your genetic diversity as a species does not increase due to hermaphrodites, then what is the point of having numerous individuals becoming pregnant.
Competition from within doesn't count against the species in terms of evolution though. If internal competition is the worst competition, then the species is doing great evolutionarily. Think about it....I'm sure you know what i mean.
So limiting the number of individuals that becomes pregnant, limits the number of new individuals and it limits the competition.
I can imagine a complex version, but I am sure you can imagine the same simple version that I am thinking of. Some organisms exist in which there are many sexes. They don't require all of the sexes to be involved, what they require is one from a sex other than themselves.Why 2? 3 is too many. Can you imagine the complexity of 3 different kind of sex.
No i haven't. But you left out Insects. They also have a xsome dependenve for sex. They do it differently (ie: no Y at all), but they still do it.Originally posted by iansmith
Have you ever wonder why only mamals have this chromosome dependent sex determination?