One consequence of genetic drift is?

Genetic drift usually only has effect on the genetic diversity of small populations of a species. Often times, genetic drift can greatly reduce the diversity of a population if a significant percent of members of the population leave by a chance event (as opposed to natural selection.) This means that their alleles for various genes leave with them.

Genetic drift does not always effect genetic diversity. Most of the time, it is the allele frequency that is affected by genetic drift.

For example, if there are 60 long-finned bass and 40 short-finned bass living in a pond, the gene frequency ratio is 3:2. If 25 short-finned are fished out, the allele frequency is now 4:1.

If all or most of the members of a population carrying a specific gene were removed from the population because of genetic drift, that would effect the genetic diversity.