Experts have differed about where the genus Varanus(monitor lizards)originated.

游客2024-01-11  19

问题 Experts have differed about where the genus Varanus(monitor lizards)originated. Because most existing species live in Australia, early researchers concluded that Varanus originated in Australia and subsequently island hopped westward along the Indo-Australian archipelago. Herpetologist Robert Mertens later argued that Varanus probably originated in the archipelago. Chromosomal analysis has since supported Mertens’ contention, and in addition, geologic evidence points to a collision between the archipelago and the Australian landmass after Varanus evolved—a fact that could account for the genus’ present distribution.
A related puzzle for scientists is the present distribution of Varanus largest surviving species, the Komodo dragon. These carnivores live only on four small islands in the archipelago where, scientists note, the prey base is too small to support mammalian carnivores. But the Komodo dragon has recently been shown to manage body temperature much more efficiently than do mammalian carnivores, enabling it to survive on about a tenth of the food energy required by a mammalian carnivore of comparable size. [br] It can be inferred that which of the following is true of the "geologic evidence"(line 6)?

选项 A、It was first noted by Mertens as evidence in favor of his theory about the origins of Varanus.
B、It cannot rule out either one of the theories about the origins of Varanus discussed in the passage.
C、It accounts for the present distribution of the Komodo dragon.
D、It has led to renewed interest in the debate over the origins of Varanus.
E、It confirms the conclusions reached by early researchers concerning the origins of Varanus.

答案 B

解析 Choice B is correct. The passage presents the "geologic evidence" so as to provide a possible explanation for the prevalence of the various species of Varanus in Australia if indeed Mertens’ theory is correct. But the evidence itself does not rule out the possibility that the earlier theory is correct and that Mertens is not, so the "geologic evidence" cannot rule out either theory. Choice A is incorrect because there is no specific indication that Mertens first provided this evidence, and the chronology of the presentation suggests that he did not. Choice C is incorrect as there is no mention in the passage of a specifically renewed interest in the debate. Choice D is incorrect since the "geologic evidence" does not rule out nor confirm either Mertens’ conclusions or those of earlier researchers.
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