evolution of species

• A mutation is a random change to genetic material and is the source of new alleles in a population.
• Mutations can:

  • be neutral
  • confer an advantage to survival
  • confer a disadvantage to the chance of survival
• Environmental factors such as:

  • radiation
  • some chemicals

  These can increase the rate of mutation.
• A new allele can result in the plant or animal being better adapted to their environment.
• Variation within a population make it possible for the population to evolve over time, in response to changing environmental conditions.
• Natural selection or survival of the fittest occurs when there are selection pressures.
• The best adapted individuals in a population survive and reproduce, passing on favourable alleles that confer a selection advantage.
• Speciation is the formation of a new species that occurs after part of a population becomes isolated by a barrier.
• The barriers that can isolate populations can be:

  • geographical
  • ecological
  • behavioural
• After a population becomes isolated, different mutations occur in each sub-population. Natural selection selects for different mutations in each group due to selection pressures.
• Each sub-population evolves, until they become so genetically different, that they are two different species.