Natural Selection

Question 1

What is natural selection

Answer 1

• Natural selection causes change in allele frequencies of a population, which can lead to evolutionary changes.
• having a single allele with selective advantage allows for the frequency of this allele to be increasingly present in the ongoing generations.
  • this is because individuals with these alleles are more likely to survive, produce and pass their traits.

Question 2

Stabilizing selection

Answer 2

• Natural selection that favours intermediate phenotypes and acts against extreme variants.
  • EX: assume being too big or too small is disadvantageous in certain environments - the middle height would be just right.

Question 3

Directional selection

Answer 3

• Natural selection that favours the phenotypes at one extreme over another, resulting in the distribution curve of phenotypes shifting in the direction of that extreme.
  • EX: if being big is better for survival, there will be an increase in population who are larger.

Question 4

Disruptive selection

Answer 4

• Natural selection that favours the extremes of a range of phenotypes rather than intermediate phenotypes; this type of selection can result in the elimination of intermediate phenotypes
  • EX: moth example.

Question 5

Sexual selection

Answer 5

• Natural selection for mating based, in general, on competition between males and choices made by females
• the difference between male and females are called sexual dimorphism.