Final answer:
The correct statement about the model of immigration and extinction rates is that small, far islands have a lower equilibrium number of species than large, far islands, which aligns with island biogeography theory. Additionally, large populations have a more stable gene pool, which protects against genetic drift.
Step-by-step explanation:
Answering the student's question, 'For the graphical model of immigration and extinction rates: a. S is not constant when the immigration rate equals the extinction rate b. Small far islands have a lower S than large far islands c. Close small islands have a higher S than close large islands d. None of the above is true: The correct statement is that small, far islands have a lower S (equilibrium number of species) than large, far islands. This is based on the theory of island biogeography, which indicates that biodiversity on an island is a function of species migration, speciation, and extinction on that island. Smaller islands support smaller populations, hence higher extinction probability, and their geographic isolation results in lower immigration rates.
Regarding the reasons for the increased vulnerability of small populations to genetic drift, the correct answer is d. The more individuals in a population, the larger and more stable is its gene pool. In larger populations, genetic diversity is higher, which helps buffer against the random fluctuations in allele frequencies that characterize genetic drift.