Follow up from Ackers
Organisms (living things) adapt to their niches by a process called 'Evolution by Natural Selection'.
At its simplest - the better the organism is suited to its environment, the longer it will live and the more offspring it will have. In the case of bacteria, the more it will grow and divide. Because DNA doesn't divide perfectly every time, you get slight variations appearing called ‘Mutations'. These happen in a random fashion and produce slightly different versions of the organism.
Most of the variations will be less well adapted to their environment, and will not compete well with the more average individuals of their species. These lines will either quickly die out or their populations will remain very low. Other variations will be better adapted than average and their populations will increase, eventually replacing the earlier type. By this process, bacteria on the edge of an extreme environment can, over generations, gradually adapt and move into it - or bacteria in an environment that’s changing can, again over generations, adapt and keep up with the demands of it's environment. Eventually you have bacteria that are so well suited to extreme conditions; they can no longer survive in their original, less extreme, environment. Over long periods of time an organism may become completely different from it's ancestral form.
Organisms have also evolved a couple of tricks to enable themselves to get access to good DNA (Genes).
Bacteria generally just divide and hope (if hope is the word) that 'the random roll of the dice' will keep their environment stable, or they will be blessed with a mutation that will enable their line to survive better (rather than more poorly). But even bacteria like to improve the odds, so if it finds itself alongside another bacterium, it will grow a tube like link and join with it. Both these bacteria can then exchange genes and give themselves a chance of getting a 'good gene' that might be being passed around the colony (Resistance to an antibiotic is a good gene for any modern forward thinking Tuberculosis bacillus, and will be passed around faster than the latest piece of hot nasty gossip).
A lot of other organisms always mix their genetic code with the code of another of their kind before reproducing. They've even evolved into two distinct versions of their species - male and female. This is called sexual reproduction. You can see in single celled organisms that early forms of this type of reproduction differed little from the bacteria's method of exchanging genes mentioned above. But later on some organisms developed 'cheaters' that hit on the idea that: if they exchange genes with a partner, they can let the partner go to all of the trouble and energy of reproducing, and they can quickly spread their genes throughout the population without reproducing at all.
These new cheater organisms had to make sure that they exchanged genes with a reproducer, not another cheater, if they were to propagate their own genes into the next generation. The regular organisms started to take genes from cheaters only, because those genes were likely to be the newest and brought from far and wide.
So now we have two versions of the same organism. The cheaters eventually became male and the reproducers female. The family line of the organism gains the advantage of being able to bring new genes into the line, and the species as a whole can spread any new good mutations through the population generation by generation. Also a new form of selection can now come into play. Sexual Selection.
Now that we have sexual reproduction, the more discerning organism is able to decide whether it wishes to share its genes with another, or find a better candidate for it's genetic material. Sexual selection is a new evolutionary force not available before that has accelerated adaptation even further. By choosing the best possible partner you can increase your chance of having offspring that will fare well in the challenges of life.
Organisms (living things) adapt to their niches by a process called 'Evolution by Natural Selection'.
At its simplest - the better the organism is suited to its environment, the longer it will live and the more offspring it will have. In the case of bacteria, the more it will grow and divide. Because DNA doesn't divide perfectly every time, you get slight variations appearing called ‘Mutations'. These happen in a random fashion and produce slightly different versions of the organism.
Most of the variations will be less well adapted to their environment, and will not compete well with the more average individuals of their species. These lines will either quickly die out or their populations will remain very low. Other variations will be better adapted than average and their populations will increase, eventually replacing the earlier type. By this process, bacteria on the edge of an extreme environment can, over generations, gradually adapt and move into it - or bacteria in an environment that’s changing can, again over generations, adapt and keep up with the demands of it's environment. Eventually you have bacteria that are so well suited to extreme conditions; they can no longer survive in their original, less extreme, environment. Over long periods of time an organism may become completely different from it's ancestral form.
Organisms have also evolved a couple of tricks to enable themselves to get access to good DNA (Genes).
Bacteria generally just divide and hope (if hope is the word) that 'the random roll of the dice' will keep their environment stable, or they will be blessed with a mutation that will enable their line to survive better (rather than more poorly). But even bacteria like to improve the odds, so if it finds itself alongside another bacterium, it will grow a tube like link and join with it. Both these bacteria can then exchange genes and give themselves a chance of getting a 'good gene' that might be being passed around the colony (Resistance to an antibiotic is a good gene for any modern forward thinking Tuberculosis bacillus, and will be passed around faster than the latest piece of hot nasty gossip).
A lot of other organisms always mix their genetic code with the code of another of their kind before reproducing. They've even evolved into two distinct versions of their species - male and female. This is called sexual reproduction. You can see in single celled organisms that early forms of this type of reproduction differed little from the bacteria's method of exchanging genes mentioned above. But later on some organisms developed 'cheaters' that hit on the idea that: if they exchange genes with a partner, they can let the partner go to all of the trouble and energy of reproducing, and they can quickly spread their genes throughout the population without reproducing at all.
These new cheater organisms had to make sure that they exchanged genes with a reproducer, not another cheater, if they were to propagate their own genes into the next generation. The regular organisms started to take genes from cheaters only, because those genes were likely to be the newest and brought from far and wide.
So now we have two versions of the same organism. The cheaters eventually became male and the reproducers female. The family line of the organism gains the advantage of being able to bring new genes into the line, and the species as a whole can spread any new good mutations through the population generation by generation. Also a new form of selection can now come into play. Sexual Selection.
Now that we have sexual reproduction, the more discerning organism is able to decide whether it wishes to share its genes with another, or find a better candidate for it's genetic material. Sexual selection is a new evolutionary force not available before that has accelerated adaptation even further. By choosing the best possible partner you can increase your chance of having offspring that will fare well in the challenges of life.
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