several individuals are entering a new population. Is this Natural Selection Genetic drift Gene flow
The scenario you described, where several individuals are entering a new population, is an example of gene flow. Gene flow refers to the transfer of genetic material (alleles) between populations through the movement of individuals or their gametes (e.g., pollen). This process can introduce new genetic variation into a population and can affect the genetic structure of both the source and recipient populations.
In contrast, natural selection is the process by which certain traits become more or less common in a population due to the effects of those traits on the individuals' survival and reproduction. Genetic drift refers to random changes in allele frequencies in a population, which can have a more significant effect in small populations.