Question

Artificial selection to obtain cows yielding higher milk output represents:

• A. stabilizing selection as it stabilizes this character in the population
• B. directional as it pushes the mean of the character in one direction
• C. disruptive as it splits the population into two, one yielding higher output and the other lower output.
• D. stabilizing folloued by disruptive as it stabilizes the population to produce higher yield ing cows.

Answer 1

The correct option is B directional as it pushes the mean of the character in one direction

Artificial selection is a man-made selection. It is the identification of the desirable traits in organisms, and the steps taken to enhance and perpetuate those traits in future generations.

Artificial selection by humans has resulted in the creation of various high yielding breeds in plants and animals. Example: Production of high milk yielding cows.

Since, this method selects only the desirable traits, it pushes the mean of the character in one direction. This type of selection is called directional selection.

In directional selection, individuals with extreme value of the trait are favoured thereby shifting the curve for the phenotypic character in that direction.

Hence, artificial selection to obtain cows yielding higher milk output represents directional selection.

In stabilising selection, the individuals with mean (average) value of the trait are favoured.

In disruptive selection, individuals at both the extreme values of the trait are favoured and individuals with mean value of the trait are eliminated. Consequently, the original population is disrupted into 2 or more separate groups that later evolve into new species.