Selective Breeding Crosses

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Selective Breeding Crosses

Knowing about genes and alleles allows you to decide which individuals to breed together.

You can then make use of the theory to help you improve the plants or animals.

It is straight forward enough.

You choose your best animals (or plants) and breed them together.

Then choose the best animals in their offspring (F1 generation).

Breed these ones again to give an F2 generation.

Carry this on over many generations until you have the 'perfect animal' - well, the one with the best characteristics or traits that you wanted.

Try this exercise: Drag and drop the correct light blue boxes over the darker blue boxes and mark your answer!

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You can easily imagine that one big reason for selective breeding is money.

You can save a lot of wasted money if you weed out weaker individuals. For example, you could selectively breed for disease resistance.

You can also ensure that you get the maximum output and therefore are more efficient. More potatoes grown on each plant means more money.

There's an old expression about putting your eggs in one basket.

If you select for certain characteristics you are selecting for certain alleles.

Over a few generations you lose those alleles from the gene pool. That is from the alleles that individuals have and that are available for passing on.

But what happens if it turns out that those lost alleles had an advantage.

Perhaps they give resistance to a new disease?

Without the allele all your best crops or animals could die!

Many domestic dogs are pedigree dogs. They are Alsatians, or Red Setters, etc.

Over many generations their characteristics have been chosen. However many breeds of dog show specific weaknesses and bad health problems.

So adopt a healthy mongrel instead! They have a good range of alleles to choose from!