There are recent reports of apparently drastic declines in amphibian populations and of extinctions of a number of the world's...
GMAT Reading Comprehension : (RC) Questions
There are recent reports of apparently drastic declines in amphibian populations and of extinctions of a number of the world's endangered amphibian species. These declines, if real, may be signs of a general trend toward extinction, and many environmentalists have claimed that immediate environmental action is necessary to remedy this "amphibian crisis", which, in their view, is an indicator of general and catastrophic environmental degradation due to human activity.
To evaluate these claims, it is useful to make a preliminary distinction that is far too often ignored. A declining population should not be confused with an endangered one. An endangered population is always rare, almost always small, and, by definition, under constant threat of extinction even without a proximate cause in human activities. Its disappearance, however unfortunate, should come as no great surprise. Moreover, chance events—which may indicate nothing about the direction of trends in population size—may lead to its extinction. The probability of extinction due to such random factors depends on the population size and is independent of the prevailing direction of change in that size.
For biologists, population declines are potentially more worrisome than extinctions. Persistent declines, especially in large populations, indicate a changed ecological context. Even here, distinctions must again be made among declines that are only apparent (in the sense that they are part of habitual cycles or of normal fluctuations), declines that take a population to some lower but still acceptable level, and those that threaten extinction (e.g., by taking the number of individuals below the minimum viable population). Anecdotal reports of population decreases cannot distinguish among these possibilities, and some amphibian populations have shown strong fluctuations in the past.
It is indisputably true that there is simply not enough long-term scientific data on amphibian populations to enable researchers to identify real declines in amphibian populations. Many fairly common amphibian species declared all but extinct after severe declines in the 1950s and 1960s have subsequently recovered, and so might the apparently declining populations that have generated the current appearance of an amphibian crisis. Unfortunately, long-term data will not soon be forthcoming, and postponing environmental action while we wait for it may doom species and whole ecosystems to extinction.
The primary purpose of the passage is to
1. Passage Analysis:
Progressive Passage Analysis
| Text from Passage | Analysis |
|---|---|
| There are recent reports of apparently drastic declines in amphibian populations and of extinctions of a number of the world's endangered amphibian species. | What it says: Scientists are hearing that amphibian numbers are dropping dramatically and some endangered species are going extinct. What it does: Introduces the basic problem that the entire passage will analyze Source/Type: Factual reports (note the cautious "apparently" - author isn't stating this as definitive) Connection to Previous Sentences: This is our starting point - no previous sentences to connect to Visualization: Imagine reports coming in: "Frog population in Region A dropped from 10,000 to 2,000 in 5 years" + "Species B officially extinct" + "Species C numbers crashing" What We Know So Far: There are reports of amphibian problems What We Don't Know Yet: Whether these reports are accurate, what they mean, what should be done Reading Strategy Insight: The word "apparently" signals the author may question these reports later |
| These declines, if real, may be signs of a general trend toward extinction, and many environmentalists have claimed that immediate environmental action is necessary to remedy this "amphibian crisis", which, in their view, is an indicator of general and catastrophic environmental degradation due to human activity. | What it says: IF the reported declines are actually happening, they might indicate all amphibians are heading toward extinction. Environmentalists say we need to act now because this crisis shows humans are destroying the environment catastrophically. What it does: Presents the environmentalist interpretation and proposed response Source/Type: Environmentalists' claims and opinions Connection to Previous Sentences: This builds on Sentence 1 by showing what some people think those reports mean and what they want to do about it Visualization: Logic chain: Reports of decline → IF true → Maybe all amphibians doomed → Environmentalists conclude: "It's a crisis! Humans are destroying everything! Act now!" What We Know So Far: Reports exist + Environmentalists think it's a major crisis requiring immediate action What We Don't Know Yet: What the author thinks about these claims Reading Strategy Insight: The phrase "if real" and putting "amphibian crisis" in quotes suggests the author may be skeptical of the environmentalist position |