共用题干 Single-parent Kids Do BestSingle mums are better at raising their kids ...

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问题共用题干 Single-parent Kids Do Best
Single mums are better at raising their kids than two parents-at least in the bird world.Mother zebra finches have to work harder and raise fewer chicks on their own,but they also produce more attractive sons who are more likely to get a mate.
The finding shows that family conflict is as important an evolutionary driving force as ecological factors such as hunting and food supply.______(46)
In evolutionary terms,the best strategy for any parent in the animal world is to find someone else to care for their offspring,so they can concentrate on breeding again.So it's normal for parents to try to pass the buck to each other.But Ian Hartley from the University of Lancaster and his team, wondered how families solve this conflict,and how the conflict itself affects the offspring.______(47)They compared single females with pairs,by monitoring the amount of food each parent collected,and removing or adding chicks so that each pair of birds was raising four chicks,and each single mum had two-supposedly the same amount of work.
But single mums,they found,put in about 25 percent more effort than females rearing with their mate.______(48)"The offspring suffer some of the cost of this conflict,"says Hartley?
The cost does not show in any obvious decrease in size or weight,but in how attractive they are to the opposite sex.When the chicks were mature,the researchers tested the"fitness"of the male offspring by offering females their choice of partner.______(49)
Sexual conflict has long been thought to affect the quality of care given to offspring,says zoologist Rebecca Kilner at Cambridge University,who works on conflict of parents in bi记S."But the experimental evidence is not great.The breakthrough here is showing it empirically".
More surprising,says Kilner,is Hartley's statement that conflict may be a strong influence on the evolution of behaviour,clutch size and even appearance."People have not really made that link,"says Har-tley.A female's reproductive strategy is usually thought to be affected by hunting and food supply. ______(50)

选项 ______(48) A:To avoid being exploited,mothers with a partner hold back from working too hard if the father is being lazy,and it's the chicks that pay the price. B:To find out, they measured how much effort zebra finch parents put into raising their babies. C:Those males reared by single mums were chosen more often than those from two-parent families. D:With two parents around,there's always a conflict of interests, which can have a detrimental effect on the quality of the offspring. E:Kilner says conflict of parents should now be taken into account as well. F:It turned out that single mums had greater influence on their offspring.

答案 A

解析此空之前的内容介绍了家庭冲突也是进化的主要推动力之一。此空处应具体地描述家庭冲突对进化的影响，故选D。
前一段的最后一句说IanHartley教授及其团队对家庭成员如何解决冲突和这种冲突对后代的影响产生兴趣，空后的内容又为他们对鸟类进行研究的具体方法和过程。故本题应选B。
此空之前的内容介绍了单身母亲比有配偶的雌性会更加努力，所以此空处的内容应为介绍具有配偶的雌性的情况，故选A。
前一句的内容主要描述了当雄性雏鸟成熟时，研究人员对其进行配偶选择方面的实验，所以此空处应接着叙述实验的结果，故选C。
最后一段的第一句说Hartley团队发现夫妻之间的矛盾冲突对于后代的行为、窝卵数，甚至是外表都会产生很大的影响。空前的一句又说人们通常认为雌性的生殖对策会受捕猎和食物供应的影响，所以此空处的内容应为建议将夫妻冲突的影响也考虑在内，故选E。

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共用题干 Single-parent Kids Do BestSingle mums are better at raising their kids ...

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