Why does breeding hard for one characteristic sometimes make another one worse?

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Question

Why does breeding hard for one characteristic sometimes make another one worse?

Accepted Answer

Linked alleles are carried along, and resources spent on one feature are lost to others — Award 1 mark. A cow bred for very high milk yield may have more health problems, for example; genes are not deleted, and offspring inherit a full set of alleles.

Answer

Selecting for one characteristic deletes the genes for all others

Answer

Breeders can measure only one characteristic in each generation

Answer

Each new generation loses half of its alleles at random

Answer

Linked alleles are carried along, and resources spent on one feature are lost to others

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