Artificial Selection

Question 1

what is genetic diversity and what increases and decreases it

Answer 1

-difference in organisms due to variation in DNA, same genes but different alleles = more likely to be able to adapt and survive

-increased by mutations leading to new alleles, also gene flow e.g migration

-decreased by: genetic bottlenecks, founder effect and selective breeding

Question 2

what is the difference between natural selection and artificial selection

Answer 2

natural- driven by selection pressures from the environment
-artificial- is driven by selection pressures from humans

Question 3

explain the process of selective breeding

Answer 3

1)The population shows phenotypic variation
2)A breeder selects an individual with the desired phenotype
3)Another individual with the desired phenotype is selected. The two selected individuals should not be closely related to each other
4)The two selected individuals are bred together
5)The offspring produced reach maturity and are then tested for the desirable trait. Those that display the desired phenotype to the greatest degree are selected for further breeding
6)The process continues for many generations: the best individuals from the offspring are chosen for breeding until all offspring display the desirable trait

Question 4

what are examples of selective breeding in crops and animals

Answer 4

-crops- large grains high gluten content, flowers with desired colour or scent
-cows with high milk yield or large meat quantity, dogs

Question 5

what are the consequences of reduced genetic diversity

Answer 5

-inbreeding depression (increased chances of 2 copies of recessive harmful alleles)
-inbreeding causes more limited gene pool therefore greater chance of gene loci being homozygous (lack of vigour, reduced fertility and potential drop in population)

Question 6

what is a solution for inbreeding depression

Answer 6

-outbreeding to create hybrid vigour (individuals that are heterozygous at many gene loci)
-can involve breeding with wild ancestral types
(wild type alleles are those that code for the most common or normal characteristic

Question 7

what are gene banks

Answer 7

-source of alleles that can be introduced back into artificially selected strains to increase vigour, store genomes in the organims

e.g,
-zoos
-botanic gardens
-seed banks
-frozen embryos
-sperm banks

Question 8

what are some advantages of selective breeding and ethical concenrs

Answer 8

-greater yields and larger profits for farmers
-food production more reliable so unlikely to be food shortages
-greater understanding of genetics

ethical concerns:
-health and welfare of animals- do domesticated animals have a value in their own right not just for human use
-loss of alleles that may benefit mankind in the future