|MadSci Network: Evolution|
There is a small chance of a small change in DNA replication during both meiosis and mitosis. This doesn't happen very often, but is enough, over time, to vary the gene pool enough to create variety and change. One thing to take into account is that evolution can occur without mutation. The variety in the gene pool is enough to create a change in the population. Let us take an extreme example. There exists some breeds of dog which have both short and long haired varieties (eg. Border Collie). This is caused by variety in the gene pool and as there is no disadvantage to either, they tend to both be around. However, let's say that global warming put the temperature right up to Carribean proportions and beyond. The long haired versions of the collie may suffer from exhaustion, overheat and may even die. This affects their ability to breed and we may find that the short haired version is found more often and the long haired one becomes rare or extinct. This is evolution at work but required no new mutation.
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