题目材料
Until recently, zoologists believed that all species of phocids (true seals), a pinniped family, use a different maternal strategy than do otariids (fur seals and sea lions), another pinniped family. Mother otariids use a foraging strategy. They acquire moderate energy stores in the form of blubber before arriving at breeding sites and then fast for 5 to 11 days after birth. Throughout the rest of the lactation (milk production) period, which lasts from 4 months to 3 years depending on the species, mother otariids alternately forage at sea, where they replenish their fat stores, and nurse their young at breeding sites. Zoologists had assumed that females of all phocid species, by contrast, use a fasting strategy in which mother phocids, having accumulated large energy stores before they arrive at breeding sites, fast throughout the entire lactation period, which lasts from 4 to 50 days depending on the species. However, recent studies on harbor seals, a phocid species, found that lactating females commenced foraging approximately 6 days after giving birth and on average made 7 foraging trips during the remainder of their 24-day lactation period.
The primary purpose of the passage is to
- Apresent evidence that several phocid species use the maternal fasting strategy
- Bexplain why the maternal strategy typically used by phocids is different from the maternal strategy used by otariids
- Cargue that zoologists' current understanding of harbor seals' maternal strategy is incorrect
- Ddescribe an unexpected behavior observed in harbor seals and propose an explanation that may account for that behavior
- Edescribe evidence concerning the maternal strategy of the harbor seal and suggest that the harbor seal belongs to the otariid rather than to the phocid family
显示答案
正确答案: D
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