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sKiTzo:
Imagine a cardboard box in which are placed many marbles of varying size and mass. In one side of that box is a hole with an iris structure allowing it to widen or constrict. You pick up the box and all you can do is shake it but because I can control the iris, I can influence what types of marbles are likely to come out. Now I surrender iris control to a complex combination of environmental factors surrounding the box and the process of marble selection begins without any guiding hand, not mine, not yours.
Organisms are born into environments which challenge them to survive. As the environment changes (shaking the box and adjusting the iris width randomly) organisms try to survive by adapting their behaviours. This may work or this may fail. If the organism can better adapt then its chances of surviving long enough to reproduce increase. If the organism cannot adapt then its chances of reproducing diminish. But this is only behavioural adaptation. Biological adaptation also occurs. The reproducing is the next step in the process.
If an organism can survive long enough to reproduce a lot, then lots of offspring will be produced. Those offspring will inherit traits from their parent (asexual organisms) or parents (sexual organisms) through the chemically mediated process of genetic heredity. Chemistry is not a perfect process and thus the duplication of genetic chemical and codes is prone to errors. Such errors are called mutations. Most such errors are so minor that they do not impact the offspring much and it's survival still depends on its adaptive behaviour and good luck. Some errors called negative mutations kill the offspring immediately or greatly disadvantage it from surviving long enough to reproduce.. Thus such disadvantaged organisms have a lower probability of surviving, reproducing and thus die out. Rarely, mutations accidentally convey a positive mutation - resulting in an advantageous characteristic (or trait) for an organism which increases its chances of survival in the changing environment around it. In such cases, with luck, the organism has a better chance of surviving long enough to do a lot of reproducing and to pass along that positive mutation to its offspring. So positive mutations and their resulting traits are more likely to lead to reproduction and persistence of positive traits. Negative traits (barring outrageous runs of good luck) more likely lead to death before reproduction, fewer offspring and thus ultimately extinction of bad traits. This selection process is called biological or genetic adaptation.
Over many generations of reproduction organisms of the same species accumulate different traits until they are so dissimilar from each other that they can no longer interbreed and become separate species. This is called speciation. It is speciation which produces the many branches of the tree of life which you have seen in diagrams. Just like individual organisms are advantaged or disadvantaged by positive or negative traits and thus selected by their inherited traits, so are entire species of organisms selected by advantage or disadvantage of many accumulated traits. Nature uses environmental pressure to try to extinguish less successful species and to promote better adapted ones. This is a process called species selection.
Nature drives this process of selection forward faster by introducing ruthless competition for resources and survival into the mix. By over-producing far more offspring than could possibly survive in an environment lethal competition drives selection more quickly and genetic adaptation accelerates. This is called natural selection within a single species and evolution across many species. Survival of the fittest partly drives genetic adaptation within a species and speciation and evolution across many species.
Continued net post.
Imagine a cardboard box in which are placed many marbles of varying size and mass. In one side of that box is a hole with an iris structure allowing it to widen or constrict. You pick up the box and all you can do is shake it but because I can control the iris, I can influence what types of marbles are likely to come out. Now I surrender iris control to a complex combination of environmental factors surrounding the box and the process of marble selection begins without any guiding hand, not mine, not yours.
Organisms are born into environments which challenge them to survive. As the environment changes (shaking the box and adjusting the iris width randomly) organisms try to survive by adapting their behaviours. This may work or this may fail. If the organism can better adapt then its chances of surviving long enough to reproduce increase. If the organism cannot adapt then its chances of reproducing diminish. But this is only behavioural adaptation. Biological adaptation also occurs. The reproducing is the next step in the process.
If an organism can survive long enough to reproduce a lot, then lots of offspring will be produced. Those offspring will inherit traits from their parent (asexual organisms) or parents (sexual organisms) through the chemically mediated process of genetic heredity. Chemistry is not a perfect process and thus the duplication of genetic chemical and codes is prone to errors. Such errors are called mutations. Most such errors are so minor that they do not impact the offspring much and it's survival still depends on its adaptive behaviour and good luck. Some errors called negative mutations kill the offspring immediately or greatly disadvantage it from surviving long enough to reproduce.. Thus such disadvantaged organisms have a lower probability of surviving, reproducing and thus die out. Rarely, mutations accidentally convey a positive mutation - resulting in an advantageous characteristic (or trait) for an organism which increases its chances of survival in the changing environment around it. In such cases, with luck, the organism has a better chance of surviving long enough to do a lot of reproducing and to pass along that positive mutation to its offspring. So positive mutations and their resulting traits are more likely to lead to reproduction and persistence of positive traits. Negative traits (barring outrageous runs of good luck) more likely lead to death before reproduction, fewer offspring and thus ultimately extinction of bad traits. This selection process is called biological or genetic adaptation.
Over many generations of reproduction organisms of the same species accumulate different traits until they are so dissimilar from each other that they can no longer interbreed and become separate species. This is called speciation. It is speciation which produces the many branches of the tree of life which you have seen in diagrams. Just like individual organisms are advantaged or disadvantaged by positive or negative traits and thus selected by their inherited traits, so are entire species of organisms selected by advantage or disadvantage of many accumulated traits. Nature uses environmental pressure to try to extinguish less successful species and to promote better adapted ones. This is a process called species selection.
Nature drives this process of selection forward faster by introducing ruthless competition for resources and survival into the mix. By over-producing far more offspring than could possibly survive in an environment lethal competition drives selection more quickly and genetic adaptation accelerates. This is called natural selection within a single species and evolution across many species. Survival of the fittest partly drives genetic adaptation within a species and speciation and evolution across many species.
Continued net post.
