2. 外语
  3. Until recently, scientists did not know of a close verte- brate analogue to the extreme form of altruism abserved in eusocial in

Until recently, scientists did not know of a close verte- brate analogue to the extreme form of altruism abserved in eusocial in

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问题 Until recently, scientists did not know of a close verte-
brate analogue to the extreme form of altruism abserved in
eusocial insects like ants and bees, whereby individuals
cooperate, sometimes even sacrificing their own oppor-
( 5) tunities to survive and reproduce, for the good of others.
However, such a vertebrate society may exist among under-
ground colonies of the highly social rodent Heterocephalus
glaber, the naked mole rat.
A naked mole rat colony, like a beehive, wasp’s nest, or
(10) termite mound, is ruled by its queen, or reproducing
female. Other adult female mole rats neither ovulate nor
breed. The queen of the largest member of the colony, and
she maintains her breeding status through a mixture of
behavioral and, presumably, chemical control. Queens have
(15) been long-lived in captivity, and when they die or are
removed from a colony one sees violent fighting for breed-
ing status among the larger remaining females, leading to a
takeover by a new queen.
Eusocial insect societies have rigid caste systems, each
(20)insects’s role being defined by its behavior,body shape, and
physiology. In naked mole rat societies, on the other hand,
differences in behavior are related primarily to reproductive
status (reproduction being limited to the queen and a few
males), body size, and perhaps age. Smaller nonbreeding
(25) members, both male and female, seem to participate pri-
marily in gathering food, transporting nest material, and
tunneling. Larger nonreaders are active in defending the
colony and perhaps in removing dirt from the tunnels.
Jarvis’ work has suggested that differences in growth rates
(30)may influence the length of time that an individual performs
a task, regardless of its age.
Cooperative breeding has evolved many times in verte-
brates, but unlike naked mole rats, most cooperatively
breeding vertebrates (except the wild dog, Lycaon pictus)
(35) are dominated by a pair of breeders rather than by a single
breeding female. The division of labor within social groups
is less pronounced among other vertebrates than among
naked mole rats, colony size is much smaller, and mating
by subordinate females may not be totally suppressed,
(40) whereas in naked mole rat colonies subordinate females are
not sexually active, and many never breed.
选项 A、Naked mole rat colonies are the only known examples of cooperatively breeding vertebrate societies.
B、Naked mole rat colonies exhibit social organization based on a rigid caste system.
C、Behavior in naked mole rat colonies may well be a close vertebrate analogue to behavior in eusocial insect societies.
D、The mating habits of naked mole rats differ from those of any other vertebrate species.
E、The basis for the division of labor among naked mole rats is the same as that among eusocial insects.
答案C
解析 The best answer is C. The first paragraph of the passage introduces the idea that the naked mole rat colony is similar to certain insect colonies. The rest of the passage provides comparisons of naked mole rat behavior with the behavior of eusocial insects (paragraphs 2 and 3) and contrast naked mole rat behavior with that of other vertebrates (paragraph 4). None of the other choices states a main idea included in the passage. Choices A and D are not correct according to lines 32-33. Choices B and E are also incorrect: in lines 19-27, naked mole rat social systems are contrasted with rigid caste systems like those of eusocial insects.
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