If a rock falls and kills 10 individuals from a population of 100 plants of the same species and the frequency of alleles changes, does the population evolve instantly from that stochastic event? Can it be said that Natural Selection is at work in this case? And how does the Synthetic Theory of Evolution help answer this question?

Explanation:

This question seeks to test the knowledge of the modern synthetic theory of evolution. This theory describes evolution as the changes occurring in the allele frequency within a population of the same specie. Hence, the following questions derived from the question can be answered as thus

1) Does the population evolve instantly from that stochastic event?

YES. This is because the frequency of the allele changed.

2) Can it be said that Natural Selection is at work in this case?

YES. The synthetic theory of evolution derives great "evidence" from natural selection because the allele frequency is believed to have changed because of the environmental impact (the rock) and that the next generation will adapt better to such an environment.

3) How does the Synthetic Theory of Evolution help answer this question?

Previously, evolution was believed to occur over several generation which ultimately lead to some phenotypic changes as a result of adaptive changes in the genes. This old description of evolution would have made one arrive at a wrong answer if one does not consider the modern synthetic theory of evolution which talks about instant evolution from allele frequency (as was described in the question).