Bottleneck effect occurs when a population suddenly gets much smaller, and genetic variation can be reduced by random genetic drift, population bottlenecks, founder effect. Given these facts, what can be reduced when a population suddenly gets much smaller among the following options:
- Pollution
 - The size of the Earth
 - Greenhouse gasses
 - The size of bottlenecks
 - The size of the environment
 - Genetic variation
 - Plant growth is reduced
 - Quality of life


 

      Genetic variation   