Lifsci 7b Xl - Working With Data: Fig 22.7 Copy Study Guide Questions And Correct Answers

In a study of species at a different location, we identify five endemic species of mammals living on an island a short distance from the mainland. We also identify each species' closest relative on the mainland. Two alternative hypotheses exist to explain this group of species: i. The ancestors of the current island species dispersed from the mainland to the island and subsequently diverged on the island (dispersal). ii. The island was originally part of the mainland, but a rise in sea level caused it to become cut off, with the result that the mammals on the island diverged from the ones on the mainland (vicariance). How would you distinguish between these two hypotheses after sequencing the same segment of DNA in representatives of all 10 species? {Ans: If the amount of genetic divergence between species in all five pairs is similar, then vicariance is the likely cause.}We know from the fossil record that three species of fish―a, b, and c―lived in an ancient lake in what is now New Jersey. Their phylogeny was as follows: Four million years ago, the lake dried out, creating two new lakes, Lake1 and Lake2. There are now a total of six species