Genetic Diversity and Adaptation

Question 1

Natural Selection.

Answer 1

1. New alleles created by random mutation.
2. If the alles are advantageous (increases chances of survival in that environment), then individuals are more likley to survive and reproduce.
3. Reproduction passes the advantageous alleles onto the next generation.
4. Over many generations, the new allele increases frequency in the population.

Question 2

Directional Selection.

Answer 2

The traits at the extremes of the range have the selective advantage.
When there is a change in the environment where these extreme traits are selected for, the individuals that posses these traits are more likley to survive to pass on their advantageous alleles to the next generation.
The frequency of the advantageous allele increases.
The extreme trait becomes the modal trait.

Question 3

Antibiotic Resistance.

Answer 3

The extremes of the range are high antibiotic resistance and low antibiotic resistance.
When the environment changes (the introduction of antibiotics), the allele for high antibiotic resistance is selected for.
Bateria with the allele for high antibiotic resistance are more likely to survive and reproduce and pass on the allele for antibiotic resistance to the next generation (by dividing by nuclear fission).
Frequency of the allele for antibiotic resistance increases in the population.
Being resistant to antibiotics becomes the modal trait.

Question 4

Stablising Selection.

Answer 4

The modal trait has the selective advantage.
Individuals with alleles for the modal trait are more likely to survive, reproduce and pass on the advantageous allele.
There is not change in the environment, so the modal trait stays the same.

Question 5

Human Birth Weight.

Answer 5

Meduin birth weight is the advantageous trait.
Too small, baby may be premature and more prone to infection.
Too large, there may be birth complications or difficulties.
Babies with a medium birth weight are more likely to survive.
Babies with low to high birth weights are less likley to survive.
Medium birth weight remains the most common trait.
The range and standard deviation decrease over time.