Question

As we have seen, inbreeding can reduce offspring fitness by exposing deleterious recessive alleles. However, some animal breeders practice generations of careful inbreeding within a family, or "line breeding," and surprisingly many of the line-bred animals, from champion dogs to prize cows, have normal health and fertility. How can it be possible to continue inbreeding for many generations without experiencing inbreeding depression due to recessive alleles? (Hint: Consider some of the differences between animal breeders and natural selection in the wild.) Generally, if a small population continues to inbreed for many generations, what will happen to the frequency of the deleterious recessive alleles over time?

a. Line breeding involves selecting only healthy individuals.
b. Line breeding introduces more recessive alleles.
c. Line breeding may involve artificial selection.
d. Line breeding decreases the frequency of deleterious recessive alleles.

Answer 1

Line breeding in animal breeding is successful in avoiding inbreeding depression by carefully selecting healthy individuals for breeding, and using artificial selection to minimize deleterious recessive alleles, thus decreasing their frequency over time.

Step-by-step explanation:

The practice of line breeding by animal breeders can allow for many generations of inbreeding without significant inbreeding depression mainly because animal breeders use artificial selection to maintain health and fertility. This is done by carefully choosing individuals for breeding based on desirable traits and overall fitness, thereby avoiding the mating of individuals with known deleterious recessive alleles. Over time, this directed breeding strategy can lead to a decrease in the frequency of harmful alleles, as those individuals carrying such alleles are not selected for breeding.

As for the direct answer to the multiple-choice question, line breeding involves selecting only healthy individuals (a), and artificial selection (c) is utilized to enhance desired traits and minimize negative genetic effects. If a small population continues to inbreed for many generations, the frequency of the deleterious recessive alleles over time will decrease, as those are intentionally bred out of the population by the selective breeding practices employed by animal breeders.