Zoology - Evolution Question with Solution | TestHub

Genetic drift:
If the change in gene frequency occurs by chance, it is called genetic drift. Sometimes the genetic drift is so prominent in the new sample of the population that newly formed population may become a different species. In this case, the original drifted population is termed as founders and the effect is called the founder effect. When there are fewer copies of an allele, larger is the genetic drift and when there is more number of copies, the effect is minimized.
Bottleneck effect - Bottlenecks are natural calamities like earthquakes, volcanic eruptions, earthquakes or storms, etc. sudden change in the environment may drastically reduce the size of the population and now this population may be genetically different from the original population. Certain alleles may have more frequency among the survivors, others may be less and some may be absent altogether. In a population that has passed through a bottleneck ultimately recovers in size, but it may have low levels of genetic variations for a long period of time and this may produce a new species.