Menge and colleagues performed experiments in which they exposed some populations of mussels to sea stars and excluded sea stars from other mussel populations. Suppose that the sea star population consists of 20 individuals and the two populations of mussels are of the same size prior to the mussel treatment. In the treatment condition, there are 500 individuals without sea stars and 100 individuals with sea stars. What is the per capita interaction strength of sea stars on mussels?
A) ln (0.2/20)
B) ln (0.5/20)
C) ln (100/20)
D) ln (500/100)

Question

Quizplus · Accepted Answer

The per capita interaction strength of sea stars on mussels is the natural logarithm of the ratio of the per capita growth rate of mussels in the absence of sea stars to the per capita growth rate of mussels in the presence of sea stars. In this case, the per capita growth rate of mussels in the absence of sea stars is 500/20 = 25, and the per capita growth rate of mussels in the presence of sea stars is 100/20 = 5. Therefore, the per capita interaction strength of sea stars on mussels is ln(25/5) = ln(5) = ln(0.2/20).

Menge and Colleagues Performed Experiments in Which They Exposed Some