What are bottleneck and founder effects?

Hint: Both effects are similar. It reduces genetic diversity in the population. Genetic diversity is the variation in genetic composition in the individual population, species and community. Diversity is the reflection of similarities and differences in the genes of individuals. Genetic drift is defined by random difference in the number of gene variants in the population. Various forms of genes are called the alleles. It decreases gene diversity.

Complete answer:
Bottleneck effect occurs during the rapid decrease in size of population. It also has different origins. It causes the sudden reduction of population size. Sudden decreases in the sense of droughts, floods, fire, disease and earthquake. It also affects the original population also. Inbreeding is defined by mating of organisms which are closely related by ancestry. So in this effect the probability of inbreeding is very high. This effect occurs due to the random sampling of genes from the original population. Examples for bottlenecked species are the northern elephant, American bison, and golden hamster.
Founder effect occurs when the small individual group is isolated from the large population. It has only one origin. It is caused due to the migration of a small group of people from the main population. It doesn’t affect the original population. Example for the founder effect is the French Canadians of Quebec, and the Amish populations in the United States.

Note:
Bottleneck effect results from habit fragmentation or and over exploitation of the species. Founder effect results in migration. Group of insects that goes into the small island by wind is the founder effect. Volcanic eruption and avalanche is also under the bottleneck effect. Random changes in the allele frequency are much faster in small populations. Natural selection is the important thing for the selection of effects.