Inbreeding & Outbreeding

Question 1

What is inbreeding?

Answer 1

• the mating of genetically closely related individuals

Question 2

What does inbreeding result in?

Answer 2

• loss of genetic diversity, which in nature will prevent evolution
• homozygosity, which can increase the chances of offspring being affected by recessive or harmful traits, thus decreasing the chances of genetic disorders

Question 3

What is inbreeding depression?

Answer 3

• the decreasing of the biological fitness of a population
• i.e. reduction of its ability to survive and reproduce

Question 4

What happens in animals as a result of inbreeding depression?

Answer 4

• have lower birth weight
• do not reproduce as successfully
• have less resistance to disease, predation and environmental stress

Question 5

What happens in plants as a result of inbreeding depression?

Answer 5

• produce less seeds
• seed germination is poor
• their resistance to stress is less

Question 6

What is the ultimate outcome of inbreeding depression?

Answer 6

• an increase in extinction rates

Question 7

What is outbreeding?

Answer 7

• the production of offspring from the mating or breeding of genetically unrelated individuals

Question 8

What does outbreeding result in?

Answer 8

• an increase in genetic variation, increasing the chance of evolution
• promotion of heterozygosity, decreasing the chances of offspring being affected by recessive or harmful treats
• a way by which new desirable traits can be introduced into the population that will have a positive effect by increasing the vigour, size and fertility of the offspring

Question 9

What is another term for outbreeding?

Answer 9

• outcrossing

Question 10

What do humans use outbreeding/outcrossing to do?

Answer 10

• to add desirable traits
• remove undesirable traits
• in both plants and animals

Question 11

What is inbreeding in humans?

Answer 11

• the mating of close relatives

Question 12

What does incest result in?

Answer 12

• offspring having a recessive genetic disease
• e.g. Tay-Sachs or haemophilia

Question 13

Why does incest result in offspring potentially having a recessive genetic disease?

Answer 13

• close relatives are much more likely to carry the same mutation for a recessive genetic disease
• thus, if the parents are related it increases the chances of the offspring receiving a harmful recessive allele from each parent
• if this happened the offspring would be homozygous for the harmful recessive alleles, which would be expressed in the offspring who would then suffer from the genetic disease