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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.
According to the passage, naked mole rat colonies may differ from all other known vertebrate groups in which of the following ways?
选项 A、Naked mole rats exhibit an extreme form of altruism.
B、Naked mole rats are cooperative breeders.
C、Among naked mole rats, many males are permitted to breed with a single dominant female.
D、Among naked mole rats, different tasks are performed at different times in an individual’s life.
E、Among naked mole rats, fighting results in the selection of a breeding female.
答案A
解析 裸鼹鼠在哪点上和其他已知脊椎动物团体不同?A．正确。体现出极强的利他性。文章一开始指出，不久以前，还没有此类脊椎动物为人所知，接着说出裸鼹鼠是这方面新发现的例证。B．群交。据最后一段，很多脊椎动物都如此。C．many males无。D．个体在不同时做不同工作。文中没有排除其他脊椎动物有此现象。E．同上。
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