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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 underground 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 insect’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 non-breeding members, both male and female, seem to participate primarily in gathering food, transporting nest material, and tunneling. Larger nonbreeders are active in defending the colony and perhaps in removing dirt from the tunnels. Jarvis’ work has suggested that differences in growth rates may influence 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 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, whereas in naked mole rat colonies subordinate females are not sexually active, and many never breed. 3. It can be inferred from the passage that the performance of tasks in naked mole rat colonies differs from task performance in eusocial insect societies in which of the following ways? (A) In naked mole rat colonies, all tasks ate performed cooperatively. (B) In naked mole rat colonies, the performance of tasks is less rigidly determined by body shape. (C) In naked mole rat colonies, breeding is limited to the largest animals. (D) In eusocial insect societies, reproduction is limited to a single female.（B） (E) In eusocial insect societies, the distribution of tasks is based on body size. 此题答案是B无可质疑，但是OG中关于C选项错误的解释，我认为不对， 在这里与各位商讨。 OG的解释如下： CHOICE C IS INCORRECT: THE PASSAGE CONTAINS NO INFORMATION ABOUT THE REALTIVE SIZE OF BREEDERS IN INCECT SOCIETIES. 但是实际上正如OG在第一题中的解释一样，原文的第二段显然是讲RAT和INSECT的相似处（A naked mole rat colony, like a beehive, wasp’s nest, or termite mound, is ruled by its queen, or reproducing female.）所以，后面讲的有关RAT的特性应该是INSECT也具有的，当然包括The queen is the largest member of the colony。 因此，C是错，因为其内容是相同点而不是DIFFERENCE. RIGHT??
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发表于 2005-4-5 01:22:00
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