Which of the following events could NOT be caused by a population bottleneck?

a. Increased population size

b. Reduction in genetic variability

c. Loss of alleles

d. Changes in allele frequency

The correct answer for this question would be option A. The event that is NOT caused by population bottleneck is increase population size. By definition, population bottleneck is an event that leads to the drastic decrease of the size of the population which may be cause by certain environmental factors, extinction, or the destruction of habitat.