So why did this one isolatedpopulation survive when all other yellow-spotted bell frogs have disappeared?
为什么当其他黄斑响铃树蛙消失时唯有这群树蛙生存了下来？
2
When cigarettes first appeared, they spread the way an infectious disease spreads through a previously isolatedpopulation.
香烟刚出现时，就象传染病一样，在各个人群中传播。
3
The study looked at breeding behaviour in an isolatedpopulation of song sparrows living in grasslands on the island of Mandarte, off the coast of Canada.