Question

5 points sa You observe the following about a population of elephants: Elephants live in two areas: one with short trees and one with tall trees. In the areas with short trees, elephant trunks are on average 2.2m long. In areas with tall trees, elephant trunks are on average 2.8m long. Design an experiment to test whether trunk size has evolved by natural selection i TTT Arial 3 (12pt) T.E E MAR 30 FS 6 9O.

Answer 1

Observing evolution through natural selection is a lengthy process since natural selection takes place through many generations and observable effects can be seen only after many generations have passed. Thus the experimental design will involve observation over decades in this case since elephants are slow reproducers.

For the experimental set up, we can tag 10 female elephants from each group (with small trunk and large trunk). We choose female elephants since their reproductive fitness and the trait heritability can be easily observed. After tagging , we shift 10 elephants of one group into the another population (for ex- 10 elephants with short trunk is shifted to the population with larger average trunk size) and vice versa. We now observe the traits of their offsprings over the generation. We should predict that the offspring of the first geneation should have moderate trunk size (anywhere between 2.2 - 2.8m). The offsprings of the 10th or so generation should have traits similar to their parents. However if we see that the traits of the offsprings slowly start to resemble that of the population we can say that natural selection is taking place. If it doesn't , we can say that natural selection is not an acting force.