Here's a paper explaining what a genetic bottleneck is. For those that don't know what a genetic bottleneck is and manufacture their own erroneous definitions, this may be eye-opening. But more than likely it will be dismissed by those that think they know everything and have come up with their own pseudoscience and set of conspiracy theories in place of learning.
Nei, Masatoshi, Takeo Maruyama, and Ranajit Chakraborty. "THE BOTTLENECK EFFECT AND GENETIC VARIABILITY IN POPULATIONS." Evolution 29, no. 1 (1975): 1-10.
I don't have a link, but here is the abstract.
"When a population goes through a small bottleneck, the genetic variability of the population is expected to decline rapidly but, as soon as population size becomes large, it starts to increase owing to new mutations. This problem is studied mathematically, and the results obtained indicate that the amount of reduction in average heterozygosity per locus depends not only on the 'size of bottleneck' but also on the rate of population growth. If population size increases rapidly after going through a bottleneck, the reduction in average heterozygosity is rather small even if bottleneck size is extremely small. On the other hand, the loss in the average number of alleles per locus is profoundly affected by bottleneck size but not so much by the rate of population growth. This difference occurs mainly because random genetic drift eliminates many low frequency alleles. However, the average number of alleles per locus increases faster than the average heterozygosity when population size is restored. Application of the theory developed to the Bogota population of Drosophila pseudoobscura supports Prakash's postulate that this population has grown very rapidly, starting from a few migrants from a Central or North American population."
Bottlenecks are the result of a population decrease with an attendant reduction in genetic diversity.
Some I have already noted confuse selection with bottlenecks. They are not the same thing.