Refer to the graph representing the Wilson-MacArthur theory of island biogeography, which explains the species-area relationship. According to the graph, the number of species on an island reaches equilibrium when
A) immigration and extinction rates are zero.
B) immigration and extinction rates are equal.
C) immigration rates rise faster than extinction rates.
D) extinction rates rise faster than immigration rates.
E) islands are large and near continents, regardless of rates.

Question

Refer to the graph representing the Wilson-MacArthur theory of island biogeography, which explains the species-area relationship.  According to the graph, the number of species on an island reaches equilibrium when
A) immigration and extinction rates are zero. 
B) immigration and extinction rates are equal. 
C) immigration rates rise faster than extinction rates. 
D) extinction rates rise faster than immigration rates. 
E) islands are large and near continents, regardless of rates.

Quizplus · Accepted Answer

According to the Wilson-MacArthur theory of island biogeography, the number of species on an island reaches equilibrium when the rate of immigration equals the rate of extinction. This is represented in the graph by the point where the two lines intersect, which corresponds to choice B, where immigration and extinction rates are equal. Therefore, the best choice is B.

Refer to the Graph Representing the Wilson-MacArthur Theory of Island