Artificial selection
Introduced| English | Meaning |
|---|---|
| selective breeding/sɪˈlektɪv ˈbriːdɪŋ/ | Breeding organisms chosen for desirable inherited characteristics over successive generations. |
| artificial selection/ˌɑːtɪˈfɪʃl sɪˈlekʃn/ | Breeding organisms chosen by humans for desirable inherited characteristics. |
| inbreeding/ˈɪnbriːdɪŋ/ | Reproduction between closely related individuals. |
| hybridisation/ˌhaɪbrɪdaɪˈzeɪʃn/ | Crossing genetically different individuals or lines to produce offspring combining traits from both. |
| gene pool/dʒiːn puːl/ | All the alleles present in a population at a particular time. |
Selective breeding 选择育种
- In selective breeding (artificial selection 人工选择), humans — not nature — choose which organisms breed.
- This passes on useful features.
- It is how we shaped our crops and farm animals.
Selective breeding (artificial selection) differs from natural selection because:
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In artificial selection, people choose the breeders to pass on useful features; in natural selection, the environment selects.
When humans choose which organisms breed to pass on useful features, it is called ______ selection.
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Artificial selection (selective breeding) is the same mechanism as natural selection — but humans, not the environment, do the selecting.
Repeated artificial selection from a few individuals can reduce the gene pool and cause inbreeding problems.
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A narrow gene pool concentrates harmful recessive alleles and lowers the population's resilience.
Examples
- breeding disease resistance into varieties of wheat and rice.
- using inbreeding 近交 and hybridisation 杂交 (crossing different lines) to make vigorous, uniform maize.
- breeding dairy cattle to improve their milk yield.
Selective breeding
Step through it. Humans take the role of the environment — choosing the breeders, generation after generation.
Which is an example of selective breeding?
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Breeding cattle for milk yield (or disease-resistant crops) is humans choosing which organisms reproduce.
Put selective breeding in order.
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Choose → breed → select offspring → repeat. Each round pushes the feature further.
Hybridisation in selective breeding means:
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Hybridisation crosses different lines (often with inbreeding) to make vigorous, uniform crops like maize.
How it is done
- Choose parents with the desired feature, breed them, and select the best offspring to breed again.
- Repeat over many generations until the feature is firmly established.
Choosing the best parents each generation makes a wanted feature more and more common
The problems with it
- Repeatedly breeding from a few "best" individuals shrinks the gene pool 基因库.
- This inbreeding can concentrate harmful alleles and leaves the population vulnerable to disease.
You've got it
- selective breeding (artificial selection) = humans choose which organisms reproduce
- examples: disease-resistant wheat/rice; inbreeding + hybridisation for maize; higher milk yield in cattle
- it passes on the features people find useful