Question

In a oak hickory forest in Pennsylvania, gray squirrel populations have been declining due to increased predation by hawks and other predators. At the same time, researchers have discovered that the average thickness of acorns in the forest have decreased by 15% due to lower feeding pressure from squirrels. What type of natural selection would this be an example of?
directional T/F

Answer 1

Answer:

Directional -------- TRUE ✔

Explanation:

Directional selection is a kind of natural selection that as the phenotype (the observable characteristics) of the species moving towards an extreme instead of the mean phenotype or the other extreme phenotype.

This type of selection is observed in environments that experienced variation over time as in weather, climate, or food availability. It gives a population bell curve for a certain trait that moves either in the left or right direction as seen in the attached image.

It is important to note that animal predators can also lead to directional selection as the slower animals in a prey population tends to be killed and eaten as the directional selection will continually skew the population in the direction of the faster animals.

Answer 2

Answer:

True.

Explanation:

This is directional because   natural elections  acted on  the small population of squirrels against the(  average thickness )  larger populated  acorns  tree in the forest.Since directional selection always shift toward larger population of organisms in population to show the particular  direction of  shift  or change  of  characteristic in a population ; then the percentage increase in the average thickness of acorns represented the direction where the   the selected characteristics was directed to  as directed by natural selection.

Therefore If a graph of number of  the population  of acorns trees and squirrel on the y axis was drawn against their  body masses on the x-axis the curve  shifts towards higher body mass indicating the  effect of selective pressures on the  smaller populated squirrels which reduces its population with a corresponding increase in  average thickness of acorns

it is therefore  an example of  directional selection,