Quiz 6 KEY
20 pts
1. On the map below, choose the areas would be expected to have the highest and lowest species richness. (4 pts)
Highest = Area __A____ _________ Lowest = Area ____D______
(A is tropical and has a large contiguous area. E is an island, which generally have lower richness. C is a peninsula, which again generally have lower richness. D is temperate and a peninsula.)
2. We discussed the productivity hypothesis to explain the latitudinal diversity gradient. Using those concepts, answer the following questions.
a. On the axes below, draw the predicted relationship between soil fertility and plant species richness. (4 pts)
b. Briefly explain why you drew the relationship as you did. (3 pts)When soil fertility is very low, few species can maintian themselves. As soil fertility increases somewhat, more species can establish. As soil fertility increases still further, competition starts to exclude species and species richness declines.
3. Phosphates have been severely restricted in laundry detergents since the 1980s. Which of the following is the fundamental reason for this restriction? (CHOOSE A SINGLE ANSWER-3 pts)
a. Phosphates interfere with the buffering capacity of the soil against acid rain.b. Phosphates decrease the ability of nitrogen fixers to function.
c. Phosphates increase the abundance of green algae in freshwater lakes.
d. Phosphates increase the abundance of blue-green algae in freshwater lakes.
e. Phosphates themselves are bad for fish.
4. Consider the following graph we used in class.
a. Assuming the slope shown significantly declines, summarize the relationship described by this graph. (3 pts)As species richness increased, the number of successfully invading species decreased.
(Be sure you recognize the distinction between the roles of independent (X axis) and dependent (Y axis) variables. Independent variables were manipulated--or at least chosen--by the researcher and are presumed to cause responses in the dependent variables. For example, the graph in this question shows that the number of plant species controls the number of invading species, NOT that the number of invading species controls the number of plant species. That second interpretation may be true, but it is not what this graph shows.)
b. How does this relationship support or refute the claims that biodiversity is important to preserve? (3 pts)
Preserving plant species richness apparently helps to prevent the invasion of non-native species. To the extent that non-native species are undesirable, preventing their invasion is a good thing. The invasion of non-native species is one of the top three causes of extinction world-wide through competition, predation, and the introduction of disease. In addition, the spread of a subset of aggressive invasive species would cause lots of different habitats to lose their unique biotic character.