When determining time since divergence, researchers compare the number of genetic differences that have accumulated among the taxa of interest. This approach is known as a molecular clock. You want to know how recently the (imaginary) striped salamander and spotted salamander diverged from their common ancestor. Spotted salamanders are found across Australia, while striped salamanders are not found anywhere else in the world except on one island off the coast of Australia. Furthermore, the striped salamander population size is small, with only a few hundred individuals. a) Would the small size of the striped salamander population make the molecular clock technique more reliable or less reliable? Justify your answer. (3-4 sentences) (2 marks) b) Spotted and striped salamanders both consume slugs, earthworms, flies, and mosquitos (in both adult and larval form). Despite their diverse diet, you notice that the spotted salamanders are absent from the island and striped salamanders are absent from the mainland. Your colleague suggests these species do not coexist due to competitive exclusion. Can we definitively say this? Provide one argument in support of this hypothesis and one against. (2-3 sentences) (2 marks)

When determining time since divergence, researchers compare the number of genetic differences that have accumulated among the taxa of interest. This approach is known as a molecular clock. You want to know how recently the (imaginary) striped salamander and spotted salamander diverged from their common ancestor. Spotted salamanders are found across Australia, while striped salamanders are not found anywhere else in the world except on one island off the coast of Australia. Furthermore, the striped salamander population size is small, with only a few hundred individuals. a) Would the small size of the striped salamander population make the molecular clock technique more reliable or less reliable? Justify your answer. (3-4 sentences) (2 marks) b) Spotted and striped salamanders both consume slugs, earthworms, flies, and mosquitos (in both adult and larval form). Despite their diverse diet, you notice that the spotted salamanders are absent from the island and striped salamanders are absent from the mainland. Your colleague suggests these species do not coexist due to competitive exclusion. Can we definitively say this? Provide one argument in support of this hypothesis and one against. (2-3 sentences) (2 marks)