The death and reproduction of the population make the mean density fluctuate but do not obviously change the overall level of population number and the population structure.

种群的死亡过程和繁殖过程使种群平均密度有较明显的波动，但对种群总体水平无明显影响，种群结构也无明显变化。

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She explains that the strategy did not work as predicted because of what's called a population level effect.

VOA: standard.2010.03.22

"If people are not able to enhance their skills in various medical specialties, therefore they cannot provide the high level of health care and services that the population needs."

VOA: standard.2010.06.01

"When you can't say for sure whether all the women in the advance provision group actually used the medication, then you're kind of looking at population level effect of a strategy, not the individual effect of a medication."

VOA: standard.2010.03.22

Problems arise from conflicts between different uses of coastal land and waters, overexploitation of coastal resources, discharge of wastes and effluents into coastal waters, increasing stress by sea level change and growth of coastal population.

UNESCO: Water Portal | Water Events Worldwide

The General Register Office for Scotland (GROS) said that while the population has fallen, Scotland's share of the UK population has not declined below the level of recent estimates.

BBC: Scotland's population falling

"You can achieve the same level of protection for the population at one-third the cost doing an intervention like this, " Fowler said.

CNN: Obesity, STDs flow in social networks