Question

Conservationists have believed that by concentrating their preservation efforts on habitats rich in an easily surveyed group of species, such as birds, they would thereby be preserving areas rich in overall species diversity. This belief rests on a view that a geographical area rich in one group of species will also be rich in the other groups characteristic of the entire regional climate zone.
Which of the following findings about widely scattered tracts 10 kilometers by 10 kilometers in a temperate climate zone would most seriously challenge the conservationists' assumptions?

• A. The tracts show little damage from human intrusion and from pollution by human activities.
• B. Where a certain group of species, such as birds, is abundant, there is also an abundance of the species, such as insects, on which that group of species feeds...
• C. The area of one of the tracts is generally large enough to contain a representative sample of the organisms in the region.
• D. There is little overlap between the list of tracts that are rich in species of butterflies and the list of those that are rich in species of birds.
• E. The highest concentration of individuals of rare species is found where the general diversity of species is greatest.

Hint:

To weaken an argument, identify its central assumption and find an answer choice that directly attacks it. Here, the assumption is "richness in A implies richness in B, C, D...". The best weakener will be a counterexample: "Here is a case where richness in A does NOT imply richness in B."

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
This is a "weaken the argument" question. The argument presents a conservation strategy and the assumption it's based on. We need to find evidence that would challenge or undermine that assumption.
Step 2: Detailed Explanation:
Let's break down the conservationists' assumption:

Strategy: Protect habitats that are rich in birds (an easily surveyed "indicator" group).
Goal: By doing this, they hope to protect areas with high overall biodiversity.
Core Assumption: "a geographical area rich in one group of species [e.g., birds] will also be rich in the other groups [e.g., butterflies, mammals, plants, etc.]".
To challenge this assumption, we need to find evidence that shows that a habitat rich in one group is \textit{not necessarily} rich in another group. In other words, we need to show that using birds as an indicator for overall biodiversity is not a reliable method. Let's evaluate the options:

(A) The condition of the tracts is irrelevant to the assumption about species distribution.
(B) This would \textit{strengthen} the assumption. It shows a positive correlation between the diversity of one group (birds) and another (insects they feed on).
(C) The size of the tracts is not the issue; the question is about the correlation of species richness across different groups within those tracts.
(D) This finding directly challenges the core assumption. It provides a concrete example where areas rich in one group (butterflies) are not the same areas that are rich in another group (birds). If the "hotspots" for birds are different from the "hotspots" for butterflies, then protecting only the bird-rich areas will fail to protect the butterfly-rich areas. This shows that birds are not a reliable indicator for all other groups.
(E) This discusses the concentration of rare species, which is related to but different from the overall species diversity (richness) that is the focus of the assumption. The assumption is about the correlation of richness between groups, not the location of rare species.
Step 3: Final Answer:
The finding that areas of high bird diversity do not overlap with areas of high butterfly diversity is a direct contradiction to the assumption that richness in one group predicts richness in others.