Question

Based on the theory of island biogeography, which of the following is the most likely reason that an island in the ocean that is 5 kilometers from a continent would have a higher number of species than one that is 15 kilometers from a continent?A) There are more species that have the ability to travel 5 kilometers than can travel 15 kilometers.B) Islands that are closer to continents always have a wider range of habitats than more distant islands do.C) There are smaller populations of each species on islands that are at greater distances from continents.D) Islands that are closer to continents always have more ecological niches than more distant islands do.

Answer 1

Answer:

The correct answer is A) There are more species that have the ability to travel 5 kilometers than can travel 15 kilometers.

Explanation:

The ecologists MacArthur and Wilson took the term island biogeography theory to refer to the predictions about the number of species that could be inhabiting on an island.

Island biogeography theory establishes that the two factors that affect species richness in natural communities on an island are the distance from the mainland and the size of the island.

At the same time, these factors affect inmigration and extinction rates. According to the theory, the inmigration rate depends on the distance between the island and the mainland, of the number of species that keep living on the mainland and not stablishing on the island and the probabilities that the species can move from the continent to the island. Islands that are closer to the continent have higher possibilities of receiving immigrants than those islands that are located farther from the mainland. This is the effect of distance.

The extinction rate depends on the area of the island, the number of species living on it and the extinction probability of these species. The effect of size is reflected in the relation between island size and species diversity. In smaller islands, the probability of extinction is higher than in bigger islands. Bigger islands can have more species than smaller ones.

In the case of two islands of the same size and different distance to the mainland, both of them will have the same extinction rate, but the one closer to the continent will have a higher immigration rate, and so, a higher amount of species. The S value will be higher on the island closer to the continent.