natural selection

• step one: new alleles for gene created by random mutation (genetic diversity)
• step two: if the new alleles increase the chances of the individual to survive in that environment, then they are more likely to survive and reproduce
• step three: this reproduction passes the advantageous allele to the next generation
• step four: as a result, over many generations the alleles increases in frequency in the population
• there are two types of natural selection: stabilising and directional
• in directional selection the phenotype at one extreme is selected for (selective advantage)
• directional selection occurs when there is a change in the environment
• directional selection causes the modal trait to change
• in stabilising selection phenotypes at extremes are eliminated and modal traits have selective advantage
• stabilising selection occurs when there is no change to the environment
• stabilising selection causes the modal traits to remain the same
• stabilising selection causes standard deviation to decrease as individuals with extreme traits decreases