Artificial selection
| English | Chinese | Pinyin |
|---|---|---|
| selective breeding | 选择育种 | xuǎn zé yù zhǒng |
| artificial selection | 人工选择 | rén gōng xuǎn zé |
| inbreeding | 近交 | jìn jiāo |
| hybridisation | 杂交 | zá jiāo |
| gene pool | 基因库 | jī yīn kù |
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:
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.
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.
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?
Breeding cattle for milk yield (or disease-resistant crops) is humans choosing which organisms reproduce.
Put selective breeding in order.
Choose → breed → select offspring → repeat. Each round pushes the feature further.
Hybridisation in selective breeding means:
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