|MadSci Network: Evolution|
The mutation within genetic information takes place during meosis, the production of sex cells (spems and eggs). In (at least) human females the eggs are produced before they are born. In human males, sperm is produced "on demand", throughout life. If any "random" mutation is going to occur, it's at this point. Female eggs suffer from degredation in quality as they age. This is why there are high risks of problems with older women having babies. The mutation that occurs in meiosis is principally random, but can be affected by such things as radiation, and maybe diet, etc. It still remains random, even if due to an external force, there is no process which goes along the lines of "it's getting hotter around here, better adjust the sperm to allow for that." That would imply that our bodies understood our genetic makeup, which woulod be some feat. The mutation is very small and very unlikely. It's not always necessary for mutation to occur in order for evolution to occur and an apparent adaption to be seen. The gene pool for a species may contain a huge variety of different genes, the "combination" of which are important. Recessive genes play an important part in making sure that the gene pool of a species stays nice and varied. Let us take the example of my dog, a border collie. Border collies are principally long haired, but mine is short. That is not due to some recent mutation in the border collie gene pool, it's merely because the gene for short hair is recessive and people prefer long haired ones, so breeding is forced to make it much more likely to be long haired. Let us imagine that global warming goes mad and the temperature in England goes up to Barbados proportions. If the border collies were left to roam free and breed without human intervention, I'm pretty sure that we would find that the long haired collies would find it a lot harder, and maybe die. All of a sudden, the short haired ones would be everywhere. This would be called an adaption, but would not have been the fault of a mutation, just a different mix of genes. Mutation gives us extra variety, but the variety already present can often be enough to give us adaption.
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