Mutations cause changes in genes. When new forms of a gene appear because of mutation, a rapid changes in species may happen if the enviroment changes.
Peppered Moths
Before the industrial revolution in Britian, most peppeed moth's were of the pale variety. They were camouflaged against the pale birch trees that they rest on. Moths with mutant black colouring were easily spotted and eaten by birds.
Airborne pollution in industrial areas blackened the birch tree with sook. This meant that the mutant black moths were now camouflaged, while the white variety became more vunerable to predators. Overtime the black peppered moths have become far more numerous in urban areas.
Antibiotic-resistant bacteria
Microorganisms such as bacteria and viruses reproduce very quickly and can evolve very fast e.g. Bacterium 'E . coli'. Its DNA can be damaged or changed when it reproduces. Most of the time this causes the death of the bacterial cell. Occasionally the mutation is beneficial for the bacterial cell. e.g. It may allow resisitance to an antibiotic
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