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  3. Until recently, scientists did not know of a close vertebrate analogue to the extreme form of altruism observed in eusocial inse

Until recently, scientists did not know of a close vertebrate analogue to the extreme form of altruism observed in eusocial inse

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问题     Until recently, scientists did not know of a close vertebrate analogue to the extreme form of altruism observed in eusocial insects like ants and bees,  whereby individuals cooperate, sometimes even sacrificing their own opportunities to survive and reproduce, for the good of others. However, such a vertebrate society may exist among un- der 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 termite mound, is ruled by its queen, or reproducing female. Other adult female mole rats neither ovulate nor breed. The queen is the largest member of the colony, and she maintains her breeding status through a mixture of behavioral and, presumably, chemical control. Queens have been long-lived in captivity, and when they die or are removed from a colony one sees violent fighting for breeding status among the larger remaining females, leading to a takeover by a new queen.
    Eusocial insect societies have rigid caste systems, each 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 limit- ed to the queen and a few males), body size, and perhaps age. Smaller non-breeding members, both male and female, seem to participate primarily in gathering food, transporting nest mate- rial, 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 may influ- ence the length of time that an individual performs a task, regardless of its age. Cooperative breeding has evolved many times in vertebrates, but unlike naked mole rats, most cooperatively breeding vertebrates(except the wild dog, Lycaon pictus)are dominated by a pair of breeders rather than by a single breeding female. The division of labor within social groups is leas pronounced among other vertebrates than among naked mole rats, colony size is much smaller, and mating by subordinate females may not be totally suppressed, whereas in naked mole rat colonies sub- ordinate females are not sexually active, and many never breed.
Which of the following most accurately states the main idea of the passage?
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 主题题型：A．“only known examples”不合原文。B．“based on a rigid caste system”是昆虫特点，恰恰不是裸鼹鼠种群特点。C．正确。裸鼹鼠种群的行为可能是某些社会性昆虫的行为在脊椎动物中的一个例子。见原文L8—12提出的结论。D．裸鼹鼠交配习惯和任何其他脊椎动物种群不同。文章最后一段有此意，但本文中心是讲裸鼹鼠的社会性，而不是此点。E．劳动分工在裸鼹鼠和昆虫中一样。与文章第三段所叙相反。
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