Plant and animal breeding Flashcards
What is artificial selection?
Intentional breeding controlled by humans for particular traits or characteristics
What are desirable characteristics for crops?
- higher yield
- higher nutritional value
- pest and disease resistance
- ability to thrive in particular conditions
Desirable characteristics for livestock?
- higher yield
- increased body composition of meat to fat ratio
- environmental tolerance
Why are plant field trials carried out?
Carried out in a range of environments to compare the performance of different cultivars/treatments and evaluate GM crops
Why do farmers have to take selection of treatments into accounts
In order to ensure a valid comparison
To show the fertiliser has made a change
Why do farmers have to take number of replicates into account and how many?
To take account of variability within samples and increase reliability
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Why do farmers randomise treatments?
To eliminate bias
The order of plots should be randomised to remove observer bias
What is in inbreeding?
Inbreeding is the mating or breeding of closely related individuals.
What happens when you inbreed?
When inbreeding is performed for long periods of time, there is a loss of heterozygosity. This means plants or animals become homozygous for the trait being selected.
When does inbreeding stop?
when the population breeds true to the desired type due to the elimination of heterozygotes
This means all the offspring are homozygous for the desired trait
What is inbreeding depression?
the accumulation of other homozygous alleles can cause the expression of deleterious (harmful) recessive alleles
What is the result of inbreeding depression?
reduced yield and a decrease in fitness in a population by reproductive failures, poor health, small litters, reduced immune system, high susceptibility to infections and shorter lives.
What is crossbreeding?
New alleles can be introduced into plant or animal species by crossbreeding with a strain exhibiting different bur desired genotype
What is produced by two different inbred homozygous cultivars
offspring that are uniformly heterozygous
What do F1 hybrids have?
Increased vigour, a bigger yield and/or increased fertility or have other improvements compared to their parents
Poorer recessive genes are masked by superior dominant genes
