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题库 / Prep2007E2-CR-1
On Pacific islands, a newly arrived gecko species, the house gecko, is displacing the previously established mourning gecko in urban areas, but populations of the two species are more stable in rural areas far from human settlement. The house gecko does not attack the mourning gecko, but in areas where insects congregate it prevents the mourning gecko from feeding on them.
Which of the following contributes most to an explanation of the difference between gecko populations in urban and rural areas?
In urban areas, geckos are valued because they eat so many insects.
Geckos defend territories against other members of the same species.
House geckos that arrive on islands are carried there in boats and planes.
In places where there are lighted buildings, insects tend to gather around the light.
Mourning geckos are all females and reproduce asexually, but house geckos reproduce sexually.
On Pacific islands, a newly arrived gecko species, the house gecko, is displacing the previously established mourning gecko in urban areas, but populations of the two species are more stable in rural areas far from human settlement. The house gecko does not attack the mourning gecko, but in areas where insects congregate it prevents the mourning gecko from feeding on them.
HG不攻击MG，但是HG会组织MG吃insects——HG取代MG，HG和MG的数量在没人的地方更稳定；
搞清楚要解释的现象是什么：urban和rural地区HG和MG数量区别的原因
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