Two opposite forces operate in the growth and development of every population. One of them is related to the ability to reproduce at a given rate. The force opposite to it is called:
1.  Fecundity
2.  Environmental resistances
3.  Biotic control
4.  Mortality

Forthcoming generations are less adaptive than their parental generation due to: 
1.  Natural selection
2.  Mutation
3.  Genetic drift
4.  Adaptation

Reason for fast speciation in present-day crop plants is:

1. Mutation

2. Isolation

3. Polyploidy

4. Sexual Reproduction