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I don't think mutation is the sole cause behind evolution. There are several other factors. Probably those factors include recombination, dominance, epistasis of certain genes and the consensus sequences determine the way their next generation gonna behave.
Only those mutations which lead to positive cause are successful and may dominate the entire species in the due course of time.
Only those mutations which lead to positive cause are successful and may dominate the entire species in the due course of time.
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Bzzzt. Lecture Mode!!
Say you have a mutated gene. That's certainly possible; on the average each germ cell you possess (egg or sperm) contains about 150 mutations from what is passed to you by your parents, and it is a randomly different set for every germ cell. Each mutation in an egg or sperm cell which combines to create a zygote will then be copied to every one of the zygote's cells, including the germ cells. The change, no longer a fresh mutation, is now in the fight for its existence, and the battleground is Darwin's Natural Selection.
Maybe 90% of all mutations are neutral, in which case the existence of the mutation in your offspring will never be noticed. Of the remainder, perhaps 90% of those will be a mutation that is lethal; it does something so bad to the recipient that it aborts during gestation (it is known about 33% of all pregnancies do end prematurely, many before the mother even knows she is pregnant). Of the remainder from that, maybe 90% will be deleterious but not fatal, and the rest will be actual improvements in some way.
If the improvements make the offspring successful at reproduction, or at any rate don't get in the way, then it is likely to get passed on. If it gets passed on enough, it will eventually become the rule rather than the exception.
How does this fit in with the group and speciation? As long as all members of the species are more-or-less equally able to mate throughout the species, then improvements will get passed on and deleterious traits will die out through the whole species. If a subgroup somehow gets isolated from the rest, though, then they only will be able to mix it up within their group, while the rest of the species members ipso facto create their own group. When this happens, the two groups no longer communicate genetically, and they have started down the road leading to two species where once there was one. They may later get back together and merge back into a single species. Or they may continue in their own pathway, especially if they face even slightly differing environments.
Say you have a mutated gene. That's certainly possible; on the average each germ cell you possess (egg or sperm) contains about 150 mutations from what is passed to you by your parents, and it is a randomly different set for every germ cell. Each mutation in an egg or sperm cell which combines to create a zygote will then be copied to every one of the zygote's cells, including the germ cells. The change, no longer a fresh mutation, is now in the fight for its existence, and the battleground is Darwin's Natural Selection.
Maybe 90% of all mutations are neutral, in which case the existence of the mutation in your offspring will never be noticed. Of the remainder, perhaps 90% of those will be a mutation that is lethal; it does something so bad to the recipient that it aborts during gestation (it is known about 33% of all pregnancies do end prematurely, many before the mother even knows she is pregnant). Of the remainder from that, maybe 90% will be deleterious but not fatal, and the rest will be actual improvements in some way.
If the improvements make the offspring successful at reproduction, or at any rate don't get in the way, then it is likely to get passed on. If it gets passed on enough, it will eventually become the rule rather than the exception.
How does this fit in with the group and speciation? As long as all members of the species are more-or-less equally able to mate throughout the species, then improvements will get passed on and deleterious traits will die out through the whole species. If a subgroup somehow gets isolated from the rest, though, then they only will be able to mix it up within their group, while the rest of the species members ipso facto create their own group. When this happens, the two groups no longer communicate genetically, and they have started down the road leading to two species where once there was one. They may later get back together and merge back into a single species. Or they may continue in their own pathway, especially if they face even slightly differing environments.
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