Option F.4 Plant and Animal Option F.4 Plant and Animal Breeding Breeding

F.4.1 Define inbreeding, F.4.1 Define inbreeding, outbreeding, interspecific outbreeding, interspecific

hybridization, polyploidy and hybridization, polyploidy and F1 hybrid vigour.F1 hybrid vigour.

InbreedingInbreeding – reproduction involving fusion of – reproduction involving fusion of gametes produced by genetically unrelated gametes produced by genetically unrelated individualsindividuals

OutbreedingOutbreeding – reproduction involving the – reproduction involving the fusion of gametes produced by genetically fusion of gametes produced by genetically unrelated individualsunrelated individuals

Interspecific hybridizationInterspecific hybridization – sexual – sexual reproduction between members of different reproduction between members of different speciesspecies

Polyploidy Polyploidy – having more than two haploid – having more than two haploid sets of chromosomessets of chromosomes

F1 hybrid vigourF1 hybrid vigour – vigour due to high levels of – vigour due to high levels of heterozygosity (the gene for specific trait are heterozygosity (the gene for specific trait are different)different)

F.4.2 Outline one example for F.4.2 Outline one example for each of the terms in F.4.1.each of the terms in F.4.1.

INBREEDINGINBREEDING

• Self-fertilization in plantsSelf-fertilization in plants

• Commonly used in domestic animals such Commonly used in domestic animals such as sheep, cattle, and pigs to strengthen as sheep, cattle, and pigs to strengthen desirable characteristicsdesirable characteristics

OUTBREEDING / INTERSPECIFIC OUTBREEDING / INTERSPECIFIC HYBRIDIZATION / F1 HYBRID HYBRIDIZATION / F1 HYBRID

VIGOURVIGOUR• Done between breeding lines within the species or even Done between breeding lines within the species or even

between the speciesbetween the species• Within species; short-horned cattle and black angus Within species; short-horned cattle and black angus

cattle were crossed to produce offspring with superior cattle were crossed to produce offspring with superior beef and rapid growthbeef and rapid growth

• Between species: horse crossed donkey to produce Between species: horse crossed donkey to produce mule which is stronger and more resistant to diseasemule which is stronger and more resistant to disease

• Between species: Macoun apple crossed with crab Between species: Macoun apple crossed with crab apple which produced the liberty apple which is similar apple which produced the liberty apple which is similar in taste to the Macoun apple but more resistant to in taste to the Macoun apple but more resistant to disease.disease.

POLYPLOIDYPOLYPLOIDY

• Produces plants which are hardier, bigger, Produces plants which are hardier, bigger, and more productiveand more productive

• Ex. Strawberries, daylilies, freesias, Ex. Strawberries, daylilies, freesias,

F.4.3 Discuss the need to F.4.3 Discuss the need to maintain the biodiversity of maintain the biodiversity of wild plants or ancient farm wild plants or ancient farm breeds a reservoir of alleles breeds a reservoir of alleles

which may have future value.which may have future value.

• The growing human population relies on The growing human population relies on three plants (rice, corn, wheat) for more three plants (rice, corn, wheat) for more than half of its foodthan half of its food

• Potato Famine in Ireland:Potato Famine in Ireland:

In 1800s Ireland relied on only a few In 1800s Ireland relied on only a few varieties of potatoes for almost all its varieties of potatoes for almost all its

food. None were resistant to a fungus that food. None were resistant to a fungus that spread quickly and in the 1840s more than spread quickly and in the 1840s more than

2 million people died of starvation2 million people died of starvation

• Research is being done into possibilities of using Research is being done into possibilities of using wild plants to become new crop plants or to wild plants to become new crop plants or to improve resistance to insects and diseases.improve resistance to insects and diseases.

• 1970s – rare species of wild corn plants was found 1970s – rare species of wild corn plants was found in Mexico which is highly resistant to diseases and in Mexico which is highly resistant to diseases and some animal pests. Luckily, it was discovered some animal pests. Luckily, it was discovered before it was wiped out.before it was wiped out.

HOW MANY ARE NOT????HOW MANY ARE NOT????

F.4.4 Explain, using wheat, F.4.4 Explain, using wheat, maize or rice as an example, maize or rice as an example,

how plant breeding how plant breeding programmes have led to an programmes have led to an

improvement in the yield of a improvement in the yield of a cereal crop.cereal crop.

WHEATWHEAT

• Cereal grass of Cereal grass of Graminae Graminae familyfamily• Has been bred to produce hundreds of different Has been bred to produce hundreds of different

varieties to:varieties to:– Increase yieldIncrease yield– Improve range of climates in which the crop can be Improve range of climates in which the crop can be

growngrown– Increase the ease with which the grain can be Increase the ease with which the grain can be

separated from the less useful parts of the plantseparated from the less useful parts of the plant

Three main species which are commonly Three main species which are commonly used:used:

• Triticum astivum Triticum astivum – flour production for – flour production for breads, cakes, and biscuitsbreads, cakes, and biscuits

• Triticum durumTriticum durum – semolina and pasta – semolina and pasta

• Triticum compactum Triticum compactum – for the production – for the production of confectionery and biscuitsof confectionery and biscuits

WHEATWHEAT

Wheat: history of Wheat: history of domesticationdomestication

Triticum monocuccum Triticum monocuccum X X Aegilops speltoidesAegilops speltoides

(2n eincorn wheat) (grass) (2n eincorn wheat) (grass)

Triticum dicoccon (emmer)Triticum dicoccon (emmer)• Tetraploid wheatTetraploid wheat

• Improved yield, threshing, and winnowing (separation of the grain)Improved yield, threshing, and winnowing (separation of the grain)

Miracle rice - short stalks (minimizes loss Miracle rice - short stalks (minimizes loss by seed dropping) and disease resistantby seed dropping) and disease resistant

ricerice

F.4.5 Outline how animal F.4.5 Outline how animal breeding programmes have breeding programmes have

led to an improvement in one led to an improvement in one of the following: milk yield in of the following: milk yield in cattle, meat yield in sheep or cattle, meat yield in sheep or

egg yield in poultry.egg yield in poultry.

Improvements have been Improvements have been achieved by improved feed, achieved by improved feed,

health, and breeding for health, and breeding for increased milk productionincreased milk production

CHICKENSCHICKENS

• Originated in AsiaOriginated in Asia

• Aggressive in nature which made them Aggressive in nature which made them suitable for exhibition fightssuitable for exhibition fights

PRODUCTS OF CROSSBREED:PRODUCTS OF CROSSBREED:

• White plymouth – meat sourceWhite plymouth – meat source

• Leghorn – for egg productionLeghorn – for egg production

• Cornish – poor layer but produces good Cornish – poor layer but produces good meatmeat

CHICKENSCHICKENS

traditional methodstraditional methods

• To ensure that original breeds are still To ensure that original breeds are still farmedfarmed

• To retain the diverse gene pool for future To retain the diverse gene pool for future breedingbreeding

INTENSIVE METHODSINTENSIVE METHODS

• Produces greater yields of saleable meatProduces greater yields of saleable meat

Intensive Methods:Intensive Methods:• Selective breedingSelective breeding• Improved feedImproved feed• Use of growth stimulatorsUse of growth stimulators• antibioticsantibiotics