Natural Selection

5.a) Based on fossil data, the researcher estimates that humans and their most closely related species in the data set diverged approximately seven million years ago. Using these data, calculate the rate of mtDNA percent divergence per million years between humans and their most closely related species in the data set. Round your answer to two decimal places.

5.b) Using the data in the table, construct a cladogram on the template provided. Provide reasoning for the placement of gibbons as the outgroup on the cladogram.

5.c) On the cladogram, draw a circle around all of the species that are descended from the species indicated by the node within the square.

4.a) The prezygotic barrier that results in these genetically distinct populations is geographic isolation.

4.b) For brook trout living in this stream, longer-finned individuals will have a higher fitness than shorter-finned individuals because they will be able to swim faster and catch more prey. This will increase their chances of survival and reproduction.

4.c) If two morphologically and behaviorally distinct populations of brook trout remain isolated for many generations, the likely impact on both populations is that they will continue to diverge genetically and may eventually become two distinct species.

4.d) The claim that there are more genetic differences between any two current brook trout populations than there are between any single current population and the ancestral brook trout population is justified because the current populations have been separated for 10,000 to 12,000 years, during which time they have accumulated mutations and experienced different selective pressures. This has led to greater genetic divergence between the current populations than between any one of them and their common ancestor.