variation & evolution key terms

• variation

  • the differences between organisms
  • can be caused by genes (e.g. eye colour), the environment (e.g. scars) or both the environment and genes (e.g. weight)
  • all variation in genes is caused by mutations
• mutation

  • mutations are changes in genes
  • most have no effect on the phenotype
  • occasionally mutations have a positive effect on phenotype and organisms with these mutations are more likely to survive
• evolution

  • the change in the genes of a population over time
  • occurs through natural selection
• natural selection

  • the process by which the individuals best adapted to the environment survive and pass on their genes
• speciation

  • occurs when two populations are so different taht they can no longer breed to produce fertile offspring
  • two new species are formed