Question

In stabilising selection

• A. individuals with the mean value of the trait are favoured
• B. individuals with the extreme value of the trait are favoured
• C. individuals with the mean value of the trait are eliminated
• D. Both a and b

Answer 1

The correct option is A individuals with the mean value of the trait are favoured

Natural selection is a process in which individuals which are physically, physiologically and behaviourally better adapted to a particular environment survive, reproduce and leave a greater number of progeny.

There are three types of natural selection: stabilising selection, directional selection and disruptive selection.

When natural selection operates in such a way that individuals with mean (average) value of the trait are favoured it is called stabilising selection. Hence, stabilising selection acts to eliminate extreme phenotypes and favour individuals with intermediate phenotypes.

When natural selection operates in such a way that individuals with both extreme values of the trait are favoured and individuals with the mean value of the trait are eliminated, it is called disruptive selection. Consequently, the original population is disrupted into 2 or more separate groups that later evolve into new species.