| (1) | Experimental material should be small and easy for keeping; |
| (2) | Easy to keep and have low mortality; |
| (3) | Short life span, you can observe more generations; |
| (4) | Reproduce rapidly and produce a large number of offsprings in each generation. Then, you can make statistics and deduction easier. |
| (5) | Traits are simple and easy observable. Not easy to make mistake. |
| (6) | Simple hypothesis and easy for analysis. |