Plant and Animal Breeding 3.2 Flashcards
What are selective breeding programmes for?
To breed only individuals with the desirable trait in hope that its passed on.
What are the characteristics selected for in crops?
Higher yield Nutritional Value Useful Physical Characteristics Ability to Thrive in a Particular Environment Resistance to Pests Resistance to Disease
What is a cultivar?
A plant that has been created or selected intentionally for desirable characteristics that can be maintained by cultivation.
What are plant field trials for?
- Compare the performance or two different plant cultivars
- Find out the effect of different environmental conditions on a new cultivar
- Determine the effect of different treatments such as fertilisers and pesticides.
Selection of Treatments
All other variables kept constant
Allows for a valid comparison
Minimum of 3 replicates to…
Take account of the variability and reduce the effects of experimental error.
Randomisation of treatments to…
Eliminate the possibility of bias.
What are the two types of variation?
Discrete and Continuous
What is discrete variation?
Can be divided up into distinct groups and is normally controlled by a single gene e.g. Pea Pod Colour
What is continuous variation?
Flows from one extreme to the other and is controlled by alleles from more than one gene (poly genetic inheritance) e.g. Weight
Is discrete variation effected by environmental factors?
No
Is continuous variation effects by environmental factors?
Yes
What is a test cross?
A cross between an organism whose genotype for a certain trait is unknown and an organism that is homozygous recessive for that trait.
What is Outbreeding?
The fusion of two gametes from unrelated members of the same species
What is inbreeding?
The fusion of two gametes from close relatives.
What does inbreeding eliminate?
Hetrozygotes
Continuous inbreeding leads to a
Loss of heterozygosity and an increase in the frequency of individuals who are homozygous.
What is inbreeding depression?
The frequency of individuals who are homozygous for recessive, deleterious alleles increases. They will do less well at surviving to reproduce.
Crossbreed populations tend to show
Improved characteristics
What are F1 Hybrids
An individual resulting from a cross between two genetically dissimilar parents of the same species.
What is Hybrid Vigour
F1 generation whose members display increased vigour so they may have increased disease resistance or growth rate.
The F2 generation would show too much
Variation
How can we stop the too much variation from F2
The two parent breeds can be maintained to produce more crossbred animals showing improved characteristics
How is genetic technology useful.
As a result of genomic sequencing, organisms with desirable genes can be identified and used in breeding programmes to improve stock.
