职称英语2015综合类考试阅读理解精选文章(2)_职称英语阅读理解

职称英语2015综合类考试阅读理解精选文章(2)

　　这种代价不是表现在身材和体重的锐减，而是表现在他们对异性有多大吸引力上。当小鸟长大后，研究者通过提供给雌性她们所选择的伴侣的方法检验雄性后代的健康情况。那些由单身母亲扶养大的雄性比由父母抚养大的雄性更多地被选中。

　　研究鸟类父母冲突的剑桥大学动词学家rebeccaKilner说，很久以来人们就认为两性之间的冲突会影响对后代的照顾。但是试验证据并不充分，这个突破主要是以经验来显示这种影响的。

　　Kilner说更为令人惊讶的是Hartley说这种冲突可能会严重影响行为的进化、窝卵数目甚至外表。Hartley说：人们并没真正确定这种联系。人们通常认为雌性的繁殖策略受捕食和食物提供方式的影响。Kilner说父母之间的冲突现在也应该被考虑在内了。

　　Single-parent Kids Do Best

　　Single mums are better at raising their kids than two parentsat 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. With two parents around, theres always a conflict of interests, which can have a detrimental effect on the quality of the offspring.