Question

Which of the following would be most likely to decrease genetic variability? Question 11 answers bottleneck genetic drift mutation random mating

Answer 1

mutation and random mating would increase, not decrease genetic variability - especially mutation, as it is the thing that introduces genetic variability into species. Genetic drift is a change in frequency of an allele, so it changes th variability, but does not decrease it necessarily, can also increase it.

the correct answer is bottleneck: it decreases the variability to only the genes that "fitted in the bottleneck".