Answer:
genetic drift
Step-by-step explanation:
Genetic drift is one of the basic mechanisms of evolution, along with natural selection, migration and mutations. This mechanism, especially important in small populations, can be defined as a change in allelic frequencies that occurs entirely randomly. Although it also affects the genetic makeup of a population, it differs from natural selection by not producing adaptations.
We can see an example of genetic drift in the above question, since if six of the beetles died randomly without reproducing, the proportion of genotypes could be quite different in subsequent generations and it would be possible to see a change in the allelic frequencies of this beetle population.