Question

26. An otter breeder discovers several pups with pointy ears. She attempts to establish a  bunch of pointy eared-otters by selling off all normal-eared pups and breeding only the pointy-eared pups. Ten generations later, she is frustrated to find that crosses between two of her pointy-eared otters still produce 70% curled and 30% normal pups. Identical twin pups invariably have the same kind of ears. She also notes that her newly formed breed is not as fertile as expected. Excluding any environmental factors What is a likely explanation for her results? (7 Points)

Answer 1

The pointed otter pack she wishes to establish so the pointy ears parental generation she has taken actually might not have been purely homozygous i.e. either of its parent was heterozygous for the ear trait so that is why we can observe some normal wildtype progeny because in F1 generation when selfed some of genic combination due to heterozygous parent came to as wildtype or normal eartype.

So she should have taken otters after sevral generation of inbreeding so in order to be sure the parents were homozygous for the desired trait.Merely choosing on basis of phenotype does not guarentee the same genotype due to classical mendelian inheritance.

The fertility also started to decrease as inbreeding increased so might be inbreeding depression was begin to set in.