Question

In the attached figure, columbines on what mountain peak are most similar phenotypically to the ancestral population of columbines (those columbines at Time = 0 years)? This information can be determined directly from the Evolutionary Tree.

A. Peak 6.

B. No such peak, since columbines on all peaks are different phenotypically from the ancestral population.

C. Peak 1.

D. Peak 2.

E. Peak 4.

800 Peak 6 Peak 1 Peak 5 Peak 2 Peak 4 Pedk 3 600 Blade Color Spur Color Petal Tips 400 Petal Color 200 Stripes

Answer 1

Answer. Peak 4 shows similarities with ancestor. But there only one difference of spur length.

Answer 2

The ancestral trait is shown at the bottom (time 0 years). The clade which is most similar to the ancestral trait will have gone through minimum changes or variations. The nodes (branching points) can be considered as variations or appearance of new traits.

Let us count the number of new traits for each peak asked in the question.

For peak 1, the following four new traits appeared: spur length, stripes, anther and petal color.

For peak 2, two new traits appeared: spur length and stripes.

For peak 4, only one new trait appeared: spur length.

For peak 6, three new traits appeared: spur length, stripes, and anther.

Thus, peak 4 has the least number of new traits as compared to the other three peaks asked in the question.

The correct choice, should be:

(E) Peak 4