Here comes the question:
A student argues that population and species living on distant islands aren't genetically isolated because individual organisms from the mainland can be blown across the ocean and reach the islands. Therefore, one wouldn't expect islands to evolve species different from those on the mainland. Which of the following would be the most serious criticism of the student's argument?
a) If populations aren't geographically isolated, then there can be gene flow and species formation will be prevented.
b) Several different species will exist on a island even though it is isolated.
c) Even though island populations are isolated, several new species can evolve because of different selection pressure on the island.
d) If an island is relatively close to a continent, highly mobile species, such as birds, can fly back and forth between the island and the mainland.
e) Entry of related organisms to island population can be sufficiently rare such that new species will evolve despite the occasional entry of outside organisms.
A student argues that population and species living on distant islands aren't genetically isolated because individual organisms from the mainland can be blown across the ocean and reach the islands. Therefore, one wouldn't expect islands to evolve species different from those on the mainland. Which of the following would be the most serious criticism of the student's argument?
a) If populations aren't geographically isolated, then there can be gene flow and species formation will be prevented.
b) Several different species will exist on a island even though it is isolated.
c) Even though island populations are isolated, several new species can evolve because of different selection pressure on the island.
d) If an island is relatively close to a continent, highly mobile species, such as birds, can fly back and forth between the island and the mainland.
e) Entry of related organisms to island population can be sufficiently rare such that new species will evolve despite the occasional entry of outside organisms.
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C) is probably the best choice because even if related mainland species can travel to the island, the island could have a different climate, ecosystem, or population and type of predator and prey (selective pressures) than the mainland that the species would have to adapt to in order to survive. This would cause the island species to take a different evolutionary track than the mainland species