Selective Breeding

Noadswood Science, 2012

Selective Breeding

What do you understand by the term ‘selective breeding’?

Labradoodle

Look at the following dogs - crossing a Poodle and a Labrador results in a ‘Labradoodle’

What features has the Labradoodle inherited from the Labrador?

What features has the Labradoodle inherited from the Poodle?

Poodle Labrador Labradoodle

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Labradoodle

The Labradoodle is large (like the Labrador), has a fluffy coat (like the Poodle) which sheds much less than a Labrador’s coat. They are also generally well tempered and good swimmers (like both its parents breeds).

So the Labradoodle has favourable characteristics from both of its parents breeds

Poodle Labrador Labradoodle

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Natural Selection Species gradually evolve by a process of natural selection

Individuals in a species show a wide variation (due to gene differences)

Individuals with inherited features best suited to their environment are most likely to survive and reproduce: passing on their genetic information to their offspring

Natural Selection Over time, a species can change its appearance, and may even

become a new species, unable to reproduce successfully with individuals of the original species

Individuals with the most favourable genes for the environment they live in are selected over time: this is natural selection

Selective Breeding Selective breeding is a process used to produce different

breeds of animals or varieties of plants that have useful characteristics

Using selective breeding you can produce a specific offspring with useful characteristics of both parents

What organisms do farmers ‘selectively breed’?

Selective Breeding Farmers can choose individual cows to mate in order to produce

a generation of cows that will yield more milk

Farmers could also selectively breed for docile animals

Apple growers want to produce a type of apple that is tasty and resistant to disease. This can be done by crossing a variety of apple known for taste with another variety that shows strong resistance to disease

Farmers could also selectively breed for crops of a uniform height / when they are ready for harvest

E.g. Cows

Suppose you wanted a variety of cow that produced a lot of milk: - Choose or select the cows in your herd that produce the most milk Only let these cows reproduce Select the offspring that produce the most milk Only let these offspring reproduce Keep repeating the process of selection and breeding until you

achieve your goal

Animals

To selectively breed animals often a ‘stud’ male is used to breed.

Artificial insemination is also used (where a vet will deliberately introduce semen into the female)

Summary

The key is to identify the feature you want, and only breed from the individuals that have that feature – it is achieved by…

Select parents with the desired traits (things you want) Cross the parents (breed them) Select from the offspring Repeat (over many generations)…

Selective breeding is used to: - Choose characteristics of the food item required Produce a more uniform crop (size / harvest time) Extend the tolerance range of an organism

Perfect Pet

Imagine you wanted to create your perfect dog – how would you selectively breed for it?

What two parents are you going to choose? What qualities do each of them have (which you want) How are you going to ‘get’ these qualities in your pet?

Draw out and annotate creating your perfect dog…

Dog Parents