Question

Stabilising selection favours

• A. Both extreme forms of a trait
• B. Intermediate forms of a trait
• C. Environment differences
• D. One extreme form over the other extreme form and over intermediate forms of a trait

Answer 1

The correct option is B Intermediate forms of a trait

Stabilising selection favours average sized individuals whereas eliminates small sized individuals. It reduces variation and thus does not promote evolutionary change. But, it maintains the mean value from generation to generation. In directional selection, the population changes towards one particular direction. It favours small or large sized individuals and more individuals of that type will be present in next generation. The mean size of the population changes. Disruptive selection favours both small-sized and large-sized individuals. It eliminates most of members with mean expression, so produces two peaks in the distribution of the trait that may lead to development of two different individuals. It is important in bringing about evolutionary change.

So, the correct answer is 'Intermediate forms of a trait'.