Question

Long necks make it easier for giraffes to reach leaves high on trees, while also making them better fighters in "neck wrestling" contests. In both cases, which kind of selection appears to have made giraffes the long-necked creatures they are today?
a. Stabilizing selectionb. Disruptive selectionc. Directional selection

Answer 1

Answer:

Directional selection

Explanation:

Natural selection is of three types :

1. Stabilizing selection: in this type of selection, genetic diversity decreases as the population stabilizes on a particular trait value. Here the mean phenotype is favored.

2. Disruptive selection is a type of selection in which extreme values for a trait are favored over the mean values thus increasing the genetic variance by favoring two extreme phenotypes.

3. Directional selection is a type of selection in which a single phenotype is favored which is of the extreme phenotype over the mean phenotype.

In the given case it can be observed that the selection is favoring long necks in case of giraffes and hence, this is an example of directional selection.