AP BIOLOGY

Detailed explanation-1: -But selective breeding, when taken to the extreme, can lead to the development of genetic disorders. And indeed, numerous dog breeds today suffer from severe health issues caused by extreme physical features. Genetic disorders are health problems caused by ‘flaws’ in an individual’s genome.

Detailed explanation-2: -Selective breeding of the disproportionately short legs of breeds such as the Basset Hound and the Dachshund has led to bowed legs and chronic problems with elbow dislocation; the short legs and long back of Dachshunds causes them to suffer more often from ruptured vertebral disks.

Detailed explanation-3: -When an interesting or useful trait is identified in a dog, owners would breed from that dog in the hope of the trait being passed on. Over many rounds of such breeding attempts, especially where two dogs with the same trait are bred with each other, traits became fixed.