This is an explanation for passage 3 of LSAT preptest 67, the October 2012 LSAT – the comparative passage. The passages are about invasive species and whether they pose a threat.
This section has paragraph summaries and an analysis of the passage, links to the explanations for the questions are below.
Paragraph Summaries
Passage A
- Conservationists now realize that invasive species can invade even healthy ecosystems.
- The everglades look healthy, but Australian invasive trees are disturbing ecosystems in the everglades. Australia itself also has problems with invasive plants.
Passage B
- Invasive species can increase ecosystem diversity.
- Invasive species transform ecosystems, rather than damaging them.
- Most invasive species are pretty harmless. The main issue is what kind of nature we’d like to be surrounded by.
Analysis
The two passages have very different philosophies. The author of the first passage clearly believes that invasive species are harmful, and that the changes they bring to ecosystems are bad.
The author of the second passage views invasive species as a mild positive force. Generally, they add to ecosystems rather than destroying them.
They both agree that invasive species can change ecosystems. They disagree on whether we should worry about invasive species.
Elton is not central to Passage A. He’s just mentioned to provide an example of an opinion the author disagrees with. Elton thought that only weak ecosystems were threatened by invasive species. The author of passage A argues that all ecosystems are at risk. The second paragraph of passage A is just an example supporting this claim.
The author of passage B thinks that invasive species make ecosystems different, but not worse, in most cases. Species counts may even go up. An invaded ecosystem may be less useful to humans, but that doesn’t necessarily make it worse or under attack.
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