What is gene flow and what is an example ?

In population genetics, gene flow (also known as gene migration or allele flow) is the transfer of genetic variation from one population to another. ... In some cases migration may also result in the addition of novel genetic variants to the gene pool of a species or population.

Gene flow is the transfer of genetic variation from one population to another.
Ex: A bee carrying pollen from one flower population to another

The higher levels in the pyramid will receive less energy.

The lower levels in the pyramid will have less predation.