Question

Suppose that two species, A and B, have similar appearances but very divergent gene sequences, while species B and C have very different appearances but similar gene sequences. Which pair of species is more likely to be closely related: A and B or B and C? Explain.

Short answer

Species B and C are more closely related because small changes in the genome can result in divergent physical appearances.

Step-by-step solution

Divergent evolution

Divergent evolution is a process in which interbreeding species accumulate differences and evolve into different evolutionary groups. The differences occur due to the changes in the environment of the species.

Species A and B

Species A and B look similar, but they have divergent gene sequences. These species must have been separated for a long time, due to which the genes have diverged greatly between them, eventually resulting in separate groups.

Species B and C

Species B and C look different but have similar gene sequences. A minute gene change can result in a diverged morphological difference between the two species.

The changes must have occurred due to the adaptations under different environmental conditions. Thus, species B and C are more closely related because they have similar gene sequences.