Lecture Notes: Selective Breeding

Introduction to Selective Breeding

Definition: Selective breeding involves choosing the best plants or animals from a population to breed together, with the goal of producing better offspring.
Historical Context:
- Humans have been practicing selective breeding for thousands of years, dating back to the beginning of agriculture.

Used frequently in modern agriculture and animal husbandry.
Examples include:
- Cows: Bred for higher meat and milk production.
- Crops: Developed to be resistant to diseases.
- Pets: Cats and dogs are bred for friendly characteristics.
- Plants: Selected for large or unusual flowers.

Selection:
- Examine the current stock (e.g., tomato plants) and choose individuals with desired traits (e.g., large tomatoes).
Breeding:
- Breed selected individuals to produce the next generation.
- Repeat the process over several generations to enhance desired traits.
Result:
- Over time, significant changes can occur, like the transformation seen in sweet corn from its original wild form.

Reduced Gene Pool:
- Definition: The gene pool encompasses all alleles present in a population.
- Selective breeding narrows the gene pool by favoring certain alleles and discarding others.
Inbreeding Risks:
- Breeding closely related individuals can lead to inbreeding.
- Results in offspring more susceptible to diseases and inherited defects.
- Example: Breeds like German Shepherds and Rottweilers are prone to health issues due to small gene pools.
Population Variation:
- Less genetic variation results in vulnerability to new pathogens.
- Example: A new pathogen could potentially decimate an entire crop like tomato plants due to lack of resistance.

Selective breeding offers advantages in improving plant and animal characteristics but comes with notable genetic risks.

End of Lecture

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