Unit 3 - Sustainability and Interdependence (Plant and Animal Breeding) Flashcards
(8 cards)
What is the function of plant and animal breeding?
Plant and animal breeding are used to improve characteristics to help support sustainable food production.
What do breeders develop crops and animals with?
- Higher food yields
- Higher nutritional values
- Pest resistance
- Disease resistance
- Ability to thrive in particular environmental conditions
What are plant field trials?
Plant field trials are carried out in a range of environments to compare the performance of different cultivars (plant selected for with a desirable characteristic) or treatments and to evaluate GM crops.
When designing a plant field trial, what must you take into account?
- Selection of treatments to ensure valid comparisons.
- Randomisation of treatments to eliminate bias when measuring treatment effects.
- Number of replicates to take into account the variability within the sample.
What is inbreeding?
Inbreeding involves two closely related relatives reproducing. This is done for several generations until the population breeds true to the desired type due to the elimination of
heterozygotes.
What is the effect of inbreeding?
The result of inbreeding can be an increase in the frequency of individuals who are homozygous for recessive deleterious alleles.
These individuals will do less well at surviving and to reproduce. This results in an inbreeding depression. This can be expressed as a decline in vigour, size, fertility, and yield of the species involved.
What is cross-breeding?
To avoid inbreeding depression, new alleles are introduced by crossbreeding individuals from different breeds. This can produce a new crossbred population that has improved characteristics. In plants, F1 hybrids (produced by the crossing of two different inbred lines), create a relatively uniform heterozgygous crop. F1 hybrids often have increased vigour and yield, known as hybrid vigour. F1 hybrids show a great deal of conformity - they are all heterozygous and show dominant phenotypes. The F2 produced by crossbreeding show a wide variation in genotypes. This produces a very variable crop with many plants displaying undesirable characteristics. As a result, F2 crops are rarely grown. To allow further productions of the F1, the two parent breeds can be maintained and crossed again to produce more heterozygous F1 hybrids in the future.
