7.10.1 Populations with low levels of levels of genetic variation have higher risk of extinction

eg. 小麦 秆锈病

7.10.2 High level of gene variation will make a population be more resilient to environmental changes

eg. 超级细菌

7.10.3 Variants that are well adapted to one environment may not be well adapted to another

eg. 镰刀形红细胞会帮你对付疟疾