17.2.7
Artificial Selection
Artificial Selection - Example
Artificial Selection - Example
Artificial selection happens when humans choose animals and crops to breed, based on their genetic characteristics. The process of the artificial selection of big cows proceeds as follows:


1) Parent selection and breeding
1) Parent selection and breeding
- Choose parents who most strongly display the desired characteristic.
- Breed the chosen parents.


2) Offspring selection and breeding
2) Offspring selection and breeding
- From the resultant offspring (children), choose the offspring that best display the desired characteristic.
- Breed these chosen offspring.


3) Repeat
3) Repeat
- Repeat this process of breeding and re-selection over many generations until all the offspring show the desired characteristic.


History of artificial selection
History of artificial selection
- Humans have done this in farming for thousands of years (with both crops and animals) to promote the genetic characteristics that we view as desirable.
Uses of Selective Breeding
Uses of Selective Breeding
Usefulness and appearance are the two most common reasons for a characteristic being considered desirable. Some useful examples are:


Crops
Crops
- Disease resistance in food crops like wheat and rice is a useful characteristic because it improves yield (food production productivity).
- Mutant alleles for gibberellin synthesis can be selectively bred into plants to produce dwarf varieties.
- This increases crop yield as more energy is used to grow the grain rather than grow the plant taller.
- Maize crops have been hybridized & inbred to produce uniformity in groups.
- Hybridization involves crossbreeding different species of corn that each have desirable characteristics.


Animals
Animals
- In farming, animals that produce more milk or meat are also useful for yield-related reasons.
- This has been done with dairy cows. Cows have the amount of milk they produce (yield) recorded.
- This allows identification of bulls that produce female offspring with high yield.
- Eggs from high-yield female cows are inseminated by such bulls. The resulting embryos are placed in surrogate cows.
- This process is repeated over many generations to produce high milk yield cows.


Dogs
Dogs
- Gentle-natured domestic dogs are useful as these animals must co-exist (live with) with humans.
Dangers of Artificial Selection
Dangers of Artificial Selection
Artificial selection can create some issues:


Inbreeding
Inbreeding
- Artificial selection can lead to inbreeding. Here, some breeds become particularly susceptible to disease or inherited defects.
- For example, French bulldogs have been selectively bred to have flat faces, but that causes them breathing problems.


Reduced variation
Reduced variation
- Artificial selection can reduce variation (differences in characteristics) within a population, making it harder for a species to adapt to environmental change.
1Cell Structure
1.1Cell Structure
1.1.1Studying Cells - Microscopes
1.1.2Introduction to Eukaryotic & Prokaryotic Cells
1.1.3Ultrastructure of Eukaryotic Cells
1.1.4Ultrastructure of Eukaryotic Cells 2
1.1.5Ultrastructure of Eukaryotic Cells 3
1.1.6Prokaryotic Cells
1.1.7Viruses
1.1.8End of Topic Test - Cell Structure
1.1.9Exam-Style Question - Microscopes
1.1.10A-A* (AO2/3) - Cell Structure
2Biological Molecules
2.1Testing for Biological Modules
2.2Carbohydrates & Lipids
2.3Proteins
3Enzymes
4Cell Membranes & Transport
4.1Biological Membranes
5The Mitotic Cell Cycle
6Nucleic Acids & Protein Synthesis
6.1Nucleic Acids
7Transport in Plants
8Transport in Mammals
8.1Circulatory System
8.2Transport of Oxygen & Carbon Dioxide
9Gas Exchange
9.1Gas Exchange System
10Infectious Diseases
10.1Infectious Diseases
10.2Antibiotics
11Immunity
12Energy & Respiration (A2 Only)
13Photosynthesis (A2 Only)
14Homeostasis (A2 Only)
14.1Homeostasis
14.2The Kidney
14.3Cell Signalling
14.4Blood Glucose Concentration
14.5Homeostasis in Plants
15Control & Coordination (A2 Only)
15.1Control & Coordination in Mammals
15.1.1Neurones
15.1.2Receptors
15.1.3Taste
15.1.4Reflexes
15.1.5Action Potentials
15.1.6Saltatory Conduction
15.1.7Synapses
15.1.8Cholinergic Synnapses
15.1.9Neuromuscular Junction
15.1.10Skeletal Muscle
15.1.11Sliding Filament Theory Contraction
15.1.12Sliding Filament Theory Contraction 2
15.1.13Menstruation
15.1.14Contraceptive Pill
15.2Control & Co-Ordination in Plants
16Inherited Change (A2 Only)
16.1Passage of Information to Offspring
16.2Genes & Phenotype
17Selection & Evolution (A2 Only)
17.2Natural & Artificial Selection
18Classification & Conservation (A2 Only)
18.1Biodiversity
18.2Classification
19Genetic Technology (A2 Only)
19.1Manipulating Genomes
19.2Genetic Technology Applied to Medicine
19.3Genetically Modified Organisms in Agriculture
Jump to other topics
1Cell Structure
1.1Cell Structure
1.1.1Studying Cells - Microscopes
1.1.2Introduction to Eukaryotic & Prokaryotic Cells
1.1.3Ultrastructure of Eukaryotic Cells
1.1.4Ultrastructure of Eukaryotic Cells 2
1.1.5Ultrastructure of Eukaryotic Cells 3
1.1.6Prokaryotic Cells
1.1.7Viruses
1.1.8End of Topic Test - Cell Structure
1.1.9Exam-Style Question - Microscopes
1.1.10A-A* (AO2/3) - Cell Structure
2Biological Molecules
2.1Testing for Biological Modules
2.2Carbohydrates & Lipids
2.3Proteins
3Enzymes
4Cell Membranes & Transport
4.1Biological Membranes
5The Mitotic Cell Cycle
6Nucleic Acids & Protein Synthesis
6.1Nucleic Acids
7Transport in Plants
8Transport in Mammals
8.1Circulatory System
8.2Transport of Oxygen & Carbon Dioxide
9Gas Exchange
9.1Gas Exchange System
10Infectious Diseases
10.1Infectious Diseases
10.2Antibiotics
11Immunity
12Energy & Respiration (A2 Only)
13Photosynthesis (A2 Only)
14Homeostasis (A2 Only)
14.1Homeostasis
14.2The Kidney
14.3Cell Signalling
14.4Blood Glucose Concentration
14.5Homeostasis in Plants
15Control & Coordination (A2 Only)
15.1Control & Coordination in Mammals
15.1.1Neurones
15.1.2Receptors
15.1.3Taste
15.1.4Reflexes
15.1.5Action Potentials
15.1.6Saltatory Conduction
15.1.7Synapses
15.1.8Cholinergic Synnapses
15.1.9Neuromuscular Junction
15.1.10Skeletal Muscle
15.1.11Sliding Filament Theory Contraction
15.1.12Sliding Filament Theory Contraction 2
15.1.13Menstruation
15.1.14Contraceptive Pill
15.2Control & Co-Ordination in Plants
16Inherited Change (A2 Only)
16.1Passage of Information to Offspring
16.2Genes & Phenotype
17Selection & Evolution (A2 Only)
17.2Natural & Artificial Selection
18Classification & Conservation (A2 Only)
18.1Biodiversity
18.2Classification
19Genetic Technology (A2 Only)
19.1Manipulating Genomes
19.2Genetic Technology Applied to Medicine
19.3Genetically Modified Organisms in Agriculture
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