genetic diversity and adaptation

Question 1

Define population

Answer 1

All the organisms of a particular species that live in the same place and can reproduce to form a fertile off-spring

Question 2

What is an allele

Answer 2

A different form of a particular gene found at the same locus

Question 3

Define genetic diversity

Answer 3

The total number of different alleles in a population

Question 4

What advantage does a high genetic diversity provide?

Answer 4

• Ability to adapt to a change in environment, allows natural selection to occur

Question 5

Explain how natural selection results in the development of new characteristics

Answer 5

• Random mutations result in new alleles, so variations exist in the gene pool
• Some alleles provide an advantage, making an individual more likely to survive and reproduce
• Their offspring receives the new allele, and frequency continues to increase over many generations

Question 6

What is directional selection

Answer 6

• Occurs when environmental conditions change
• Individuals with phenotypes suited to new conditions will survive and pass on their genes
• Over time the mean of the population will move towards these characteristics

Question 7

What is stabilising selection

Answer 7

• Occurs when environmental conditions stay the same
• Individuals closest to the mean are favoured, and any new characteristics are selected against
• Results in low diversity

Question 8

Define a niche

Answer 8

The role of a species within its environment

Question 9

What are the 3 types of adaptation?

Answer 9

1. Anatomical = changes to body structure
2. Physiological = changes to bodily processes
3. Behavioural = changes to actions

Question 10

When does genetic diversity occur?

Answer 10

• During meiosis when chromosomes are crossing over and during independent segregation
• Frameshift mutations
• Range of characteristics in phenotype
• During selection pressure

Question 11

What increases genetic diversity

Answer 11

1. Mutations in the DNA which form new alleles
2. Gene flow when different alleles are being introduced into a population when individuals from another population migrate into them and reproduce

Question 12

What is required for natural selection to occur?

Answer 12

Genetic diversity

Question 13

Describe a genetic bottleneck

Answer 13

• It is an event that causes a big reduction in a population
• This reduces the number of different alleles in the gene pool and so reduces genetic diversity
• The survivors reproduce and a larger population is created from a few individuals

Question 14

What does a genetic bottleneck do to genetic diversity?

Answer 14

Genetic bottleneck reduces diversity

Question 15

Describe a founder effect

Answer 15

• A few organisms from a population start a new colony and there are only a small number of different alleles in the initial gene pool
• The frequency of each allele in the new colony might be different from the frequency of those alleles in the original population, the allele that was rare in the original population might be more common in the new colony

Question 16

What does a founder effect do to genetic diversity?

Answer 16

Founder effects reduce genetic diversity