Genetic differences caused by different genes in the individuals. Genetic variation arises as a result of:
- Mutations - sudden changes to genes and choromasome
- Meiosis - special form of nuclear division that gorms gametes
- Fusion of gametes - sexual reproduction cause offspring to inherit parental characteristics
Variety in asexually reproduction organisms can only be increased by mutations
Environmental differences: these influences affect the way the organism's genes are expressed. The genes set limits, but it is largely the environment that determines where, withough those limits, an organism lies. Environmental influences include, climatic conditions, temperature, rainfall, sunlight, soil conditions, pH and food availability
In most cases of variation is due to the combined affects of genetic differences and environmental influences. It is very hard to distinguish between the effects of many genetic and environmental influences that combine together,
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