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Author | Topic: Asexual to sexual reproduction? How? | |||||||||||||||||||||||
Lithodid-Man Member (Idle past 2958 days) Posts: 504 From: Juneau, Alaska, USA Joined: |
Paulk writes: In a hermaphroditic species it can be an advantage to be male. Males invest fewer resources in the reproductive process itself, so a successful male can produce more offspring than a hermaphrodite. Paul, you are dead-on in this. While it doesn't directly relate to the evolution of sex it is a major factor in the maintenance of the simultaneous hermaphroditic system. In species using this system there is always strong selective pressure to 'cheat', reproduce only as a male. And in those species (all of them that I know of) there are factors in place to prevent this. Some fishes, like Serranidae (groupers) have a very long mating process that involves the release of a few eggs from one, a little sperm from the other, some eggs from the other, and so on. This prevents one from merely fertilizing the eggs of the other. They go back and forth until both are empty. In some simultanously hermaphroditic shrimp they live in monogamous pairs. The ovarian development is bright green and visible though the carapace. This insures both partners know the reproductive state of the other. A very good hypothesis on the 'love darts' of terrestrial snails suggests that they may also be anti-cheating mechanisms. The courtship period involves destructive impalement by both members. They literally stab each other all over with serrated blades! In some species there is a high degree of mortality associated with this. The numbers game involves the probability of you or your mate being killed . It sounds bizarre (and it is!) but it works out. If you mate only as a male but are killed you ultimately win. But if you cheat and your partner dies, you lose (you have no eggs, and your sperm dies with them). So it works out to not cheat and hedge your bets by reproducing both ways. This way, unless both are killed, your genes are passed on. Wanda: To call you stupid would be an insult to stupid people. I've known sheep who could outwit you. I've worn dresses with higher IQs, but you think you're an intellectual, don't you, ape? Otto: Apes don't read philosophy. Wanda: Yes they do, Otto, they just don't understand it. "A Fish Called Wanda"
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RAZD Member (Idle past 1432 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Its being realistic. No it isn't. Being realistic is to say that we don't know what the possibilities are\were, thus we cannot say that it was improbable, nor can we say that it was highly likely. I really fail to understand why the probability issue is so hard to grasp realistically. Let's say I have three di in my hand. Each one has a number of sides on it, but you don't know how many and each could be different. You don't know if the sides are equal or not, or if they are perpendicular to the center of mass of the di, thus each side could have different metastable conditions affecting likelyhood of balance on that face. You don't know how the di are marked. What is the probability that I will throw a "7" eh? You can't even calculate how many different possibilities of arrangements there are that affect the calculation of the possibilities of results. The realistic answer is "we don't know - there isn't enough information to know" and any pretense otherwise is just a logical fallacy of one kind or another.
I have asked the question why nature would have selected sex over asexual reproduction. The answer that comes back is that if evolution was involved then there was either a survival advantage or a reproductive advantage. And likely the later, seeing as an organism that develops a feature that allows it to cause other organisms to reproduce its offspring doesn't have to spend its resources and energy on the process, and so it has more time and energy to use causing other organisms to reproduce its offspring. Also as noted there are bacteria that inject DNA into other bacteria, and there are snails that wage the war of the sexes at a very basic level: whoever impregnates the other gets to play the "daddy" role, they get an offspring without having to spend its resources and energy on the process, and so it has more time and energy to use causing other snails to reproduce its offspring, while the other gets to play the "mommy" role and has to spend its resources and energy to form and bear the offspring before getting back into the battle: there are life forms that exhibit intermediate stages between complete asexual reproduction and complete sexual reproduction. {abe} see Message 42 for some comments on the evolution stages of sex {/abe}
In a static population there is usually only one offspring per set of parents survives to adulthood. Not at all. There are usually way more offspring produced in the course of reproductive life of the parents, even for ones that only bare 1 young per pregnancy (and which is not the norm eh?). There are usually way more offspring than there are parents, whether the population is static, increasing or decreasing. What controls the population size is natural selection, not birth rate.
... asexual reproduction is twice as fast as sexual reproduction, ... You are comparing apples and oranges. Consider a process whereby you would have to split down the middle and progressively fill in the gap with copies of cells from the right side onto the left side and from the left side onto the right side until the two halves could seperate into two new individuals. You would need much more cell division -- PLUS cell migration to the appropriate place -- than occurs in the development of a fetus, and based on time for that cell division ALONE to take place it would take much longer.
Then you have long periods of gestation, ... Not for the male. The male has zero time for gestation and rarely needs more than a few minutes to be ready for the next mating. This also means that the males have time and energy to provide defense for their offspring (and any females that are producing them), so that rather than a whole population of individuals incapacitated by dividing down the middle for over a year or so, you have some to ward off predators so the whole population can survive.
How, then, is sexual reproduction less costly than asexual propagation? For the same reason that having specialized organs within an organism is less costly than having all the cells capable of doing all the jobs: specialization and sharing. Think of a population of a sexual species as a number of super organisms, where individuals are specialized organs within a {population body} -- it is essentially "asexual" in its reproduction of new {population bodies} of the same species, and the {population body} divides when conditions are right, without input from other {species}. (hmm. this applies to the Is death a product of evolution too ... ) Enjoy. Edited by RAZD, : typo, added ref to Lithodid_Man's excellent post we are limited in our ability to understand by our ability to understand RebelAAmericanOZen[Deist
... to learn ... to think ... to live ... to laugh ... to share.
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timothy44 Inactive Member |
Evolutionists can't explain Origin of Gender and Sexual Reproduction
In their article entitled The Origin of Gender and Sexual Production the authors Bert Thompson, Ph.D. and Brad Harrub, Ph.D. wrote the following:
quote: Secondly, creationists Jonathon Safarti and Michael Matthews wrote:
quote: The evolutionist apologetic website TalkOrigins.org poorly attempts to defend the evolutionary position regarding the origin of gender and sexual reproduction by stating the following:
quote: The creationist apologetic website CreationWiki responds to TalkOrigins.org by responding:
quote: The evolutionist apologetic website TalkOrigins also defends the evolutionary position quite poorly by stating:
quote: CreationWiki.org effectively responds by stating:
quote: Lastly, I would ask the evolutionists this question which a friend of mine posed to an evolutionist: The human female reproductive mechanism uses scent. The mechanism gives a scent that only attracts the sperm cells that it was designed to attract. How could this mechanism evolve step-by-step? References CreationWiki ,(Talk.Origins) Sex can't have evolved at: Sex can't have evolved (Talk.Origins) - CreationWiki, the encyclopedia of creation science Jonathon Safarti and Michael Matthews, Argument: Evolution of sex at:
Design in Nature
| Answers in Genesis
Bert Thompson, Ph.D. and Brad Harrub, Ph.D. , The Origin of Gender and Sexual Reproduction at http://www.apologeticspress.org/articles/136
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AdminNosy Administrator Posts: 4754 From: Vancouver, BC, Canada Joined: |
Since much of your post has been discussed in this thread but you posted exactly what you put in the new thread without change or reference to those discussions I wonder if you intend to debate and discuss in good faith.
If you don't you will lose posting priviledges for periods of time. I suggest that your next post demonstrate that you have actually read this thread.
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timothy44 Inactive Member |
I thought BertThompson, PHD made some points that the evolutionists at this forum did not address. For example, the Thompson quote states and pay close attention to the bolded portions:
quote: Also, even a proevolutionary position science journal article was forced to admit:
quote: Lastly, I thought this question posed to evolutionists was very relevant: Lastly, I would ask the evolutionists this question which a friend of mine posed to an evolutionist: The human female reproductive mechanism uses scent. The mechanism gives a scent that only attracts the sperm cells that it was designed to attract. How could this mechanism evolve step-by-step? Edited by timothy44, : No reason given. Edited by timothy44, : No reason given.
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Chiroptera Inactive Member |
I don't understand your continued questions.
When pressed to answer questions such as, “Where did males and females actually come from?,” “What is the evolutionary origin of sex?,” evolutionists become silent. Well, no, Lithodid-Mand was not silent. He attempted to answer the question.
Philip Kitcher noted: “Despite some ingenious suggestions by orthodox Darwinians, there is no convincing Darwinian history for the emergence of sexual reproduction.” What was unconvincing about L-man's explanation? -
quote: Is this really hard? Let's imagine a scenario. Cells always emit waste products. Some of these waste products will be proteins and metabolic wastes that are only produced by cells. Many single-celled organisms exhibit chemotaxis -- that is, they are attracted or repelled by sources of certain chemicals in the environment, indicating food to be consumed or poisons to be avoided. It may take a slight change in the detection machinery to become sensitive to particular metabolic products, and so be attracted to a potential food source and (in the case of sexual reproduction, or the pseudo-sexual reproduction described by L-man) potential mates. Once a species exhibits this sort of attraction to other cells, a cell which produces (and so emits) a protein that is better at triggering the attraction mechanism in a member of the same species will attract more mates than other cells which do not. Now you have a positive feedback system, where the emitted chemicals are better at attracting the other cells, and the detecting mechanisms become better at detecting this chemical. This system is then incorporated into the sexual reproduction mechanism as multicellularity evolves. Kings were put to death long before 21 January 1793. But regicides of earlier times and their followers were interested in attacking the person, not the principle, of the king. They wanted another king, and that was all. It never occurred to them that the throne could remain empty forever. -- Albert Camus
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timothy44 Inactive Member |
Chiroptera,
You wrote:
quote: For one, I don't believe he adequetly addressed the following by Dr. Thompson:
quote: Secondly, I don't think he adequately adressed CreationWiki's objections.
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Chiroptera Inactive Member |
Hi, tim.
I have to give you a bit of a warning before the moderators do: it is considered bad form here to simply quote other sources without adding content of your own. In your case, you are giving the impression that you are not reading the other posts. For example:
quote: A moderator is going to pop in here and get angry if you don't give a more detailed explanation why L-man's description is not adequate. I mean, he did explain how female and male differentiation occurred. I'm not sure myself that it is correct, but what problems do you have with it? -
quote: I don't understand the CreationWiki quote. Why don't you explain the problem in your own words? Kings were put to death long before 21 January 1793. But regicides of earlier times and their followers were interested in attacking the person, not the principle, of the king. They wanted another king, and that was all. It never occurred to them that the throne could remain empty forever. -- Albert Camus
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timothy44 Inactive Member |
Chiroptera,
You wrote:
quote: What is it that you don't understand about the CreationWiki quotes I cited in my post?
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platypus Member (Idle past 5781 days) Posts: 139 Joined: |
What is the date of the sources you are quoting? Research in hot fields like sexual reproduction evolve rapidly and new explanations can arise in as little as 5 to 10 years. I mean, Lithoid-Man offered a very good explanation of sex, and I bet his research was performed after that book.
Also, statements like this:
quote:lead me to believe that you think the pure existence of sex is absurd, rather than the origination of sex being absurd. This sort of concern is outside the scop of this thread, but even more importantly, if sex is so absurd, why was it "designed"? The absurdity of sex is evidence against a designer if anything. Now, I'm not familiar with this literature, but statements like quote:indicates that there are "currently competing hypotheses," or possible explanations out there. There is simply not enough data to choose a correct one yet. This does not say sexual reproduction is incompatible with evolution. It only says the mechanism of sexual reprduction is currently unknown, but compatible explanations exist. Which doesn't say anything new, this is why we still do science, because we don't know everything yet. And this is making your whole argument sound like an irreducible complexity argument. quote: Sounds to me a lot like the way a flower attracts a pollinator. I think Chiroptera's explanation of a positive feedback loop fits the bill pretty well.
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Chiroptera Inactive Member |
quote: Given this is admitted:
Theoretically , gradual origin of amphimixis from apomixis, with each step favored by natural selection, is feasible. I don't understand why this is a problem:
However, we still do not know how this process occurred nor what selection caused it.... Evolution of many aspects of reproduction requires more theoretical studies, while the existing data are insufficient to choose among the currently competing hypotheses. Kings were put to death long before 21 January 1793. But regicides of earlier times and their followers were interested in attacking the person, not the principle, of the king. They wanted another king, and that was all. It never occurred to them that the throne could remain empty forever. -- Albert Camus
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timothy44 Inactive Member |
CreationWiki doesn't admit the validity of that quote. It merely states that TalkOrigins did not adequetly represent what the article actually stated as can be seen by the abstract.
Now please address the other CreationWiki material I cited.
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Chiroptera Inactive Member |
quote: What? It is almost the entirety of the passage that you quoted. You see? This is the problem. It's not clear what you are trying to say here. Write a passage in your own words what the problem is. If you cannot explain, in your own words, the problem you see with the evolutionary explanation, then I will assume that you do not understand your own sources and that you are merely spamming the board with cut'n'paste quotes you do not comprehend. I will also warn you that the moderators of this board are going to make the same assumption. Kings were put to death long before 21 January 1793. But regicides of earlier times and their followers were interested in attacking the person, not the principle, of the king. They wanted another king, and that was all. It never occurred to them that the throne could remain empty forever. -- Albert Camus
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timothy44 Inactive Member |
Chiroptera,
I can see you really don't want to address the CreationWiki material. No need to carry on our "dialogue". Edited by timothy44, : No reason given.
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timothy44 Inactive Member |
double post
Edited by timothy44, : No reason given.
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