PLEASE, NEED HELP WITH ALL THE QUESTIONS Diversity and Island Biogeography 1. Fo

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PLEASE, NEED HELP WITH ALL THE QUESTIONS

Diversity and Island Biogeography

1. For West Indian land-bird data, the best-fitting species-area curve is a power function (S = c*Az) with the constants c = 8.759 and z = 0.113. The island of Grenada has an area of 120 square miles, and supports 17 land-bird species.

- What is the predicted number of species from the power function?

- Suppose that half of the island’s area disappears in a volcanic eruption. From the power function, how many species would be expected to remain?

2. Your colleague returns from the South Pacific with data on island lizards. “Look,” they say, “my data show that there are more species of lizards on small islands than large islands. This disproves the MacArthur-Wilson equilibrium model!” Using an appropriate set of immigration and extinction curves, show how more species could occur on a small island (A2) than on a large island (A1) in the McArthur-Wilson model.

3. Suppose that an island in MacArthur-Wilson equilibrium supports 75 species, out of a source pool of 100 species. The maximum extinction rate (E) is 10 extinctions per year. Calculate the maximum immigration rate (I). If I is doubled, what is the new species equilibrium and new turnover rate?

4. Define the target effect. Use a graph of immigration and extinction rates as a function of the number of species on an island to illustrate the impact of the target effect on the equilibrium number of species.

5. Define the rescue effect. Use a graph of immigration and extinction rates as a function of the number of species on an island to illustrate the impact of the rescue effect on the equilibrium turnover rate of species.

Explanation / Answer

1) The power function of the species area curve is given by the formula,

S = C x (A) z

Where, S represents the number of species, C represents the intercept, A is the area covered and Z is the slope of the curve.

120 sq.m = 310798573 sq.m

Here, S = 8.759 x (310798573) 0.113

S = 8.759 x 9.11

S = 79

So, the predicted number of species from power function is 79.

When the land area is reduced by half due to volcanic eruption, the predicted number of species will be,

S = 8.759 x 8.426

S = 73

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