POPULATION BOTTLENECK

=Population Bottleneck= [image:http://i.imgur.com/dg0wsGj.png] A population bottleneck occurs when a population is reduced to a small number of survivors. This can occur because of natural seasonal climatic change, heavy predation, disease or catastrophic events (e.g. floods, volcanic eruptions, landslides). The small number of individuals that survive will not be representative of the original, larger gene pool. Some alleles will be over-represented, some will be under-represented and some alleles will have been lost entirely. Even once the population has recovered the allele frequencies won't be the same as they were in the original population. Population bottlenecks reduce the genetic diversity of a population because they result in the loss of some alleles. Following a bottleneck, the small surviving population will be impacted more severely by '''genetic drift''' and '''inbreeding'''. A population bottleneck is very similar to the founder effect. Both have a similar impact on allele frequency. The only difference is that a bottleneck occurs when a population is reduced to a small number of survivors and the founder effect occurs when a small number of individuals emigrate and establish a new population.