Genetic Drift In Katrina

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Natural environmental disasters can shape the genetic make-up of not only humans but all animals. One disaster can change an entire population’s structure, allele frequencies, and outlook. Hurricanes are a type of natural disaster that can demonstrate two specific examples of genetics which are population bottlenecks and genetic drifts. A specific example of how bottleneck effects and genetic drift can occur in areas where hurricanes are prevalent in is Hurricane Katrina. When looking at Hurricane Katrina, the population bottleneck effect and genetic drift played important aspects in the state of Louisiana’s population, but more specifically in the city of New Orleans. A population bottleneck occurs when the parent population is reduced …show more content…

Hurricane Katrina caused allele frequencies in New Orleans and the state of Louisiana to change which can cause the new population to be genetically different than the pre-Katrina population. There was a 75% out-migration of people in the “toe” of Louisiana once Hurricane Katrina hit, but there was an influx of in-migration to the in-land counties of Louisiana. The areas in the “toe” were hit the hardest by Hurricane Katrina due to the large amount of flooding from the levee failure causing a larger volume of people to out-migrate. The people that out-migrated caused their allele frequencies to be a lot lower than before because they won’t be present in that population anymore. The areas that had a large influx of people were inland from the areas hit the worse. This would cause the genetic variation to increase in the inland areas which can result in new mutations. In terms of specific racial groups more than 175,000 African Americans left New Orleans after the storm and 75,000 never returned. The allele frequencies present in the African American communities will be completely different due to the 75,000 people not returning which would cause a reduction of the population size. The reduced population size will have some effect on the allele frequencies. Some alleles may no longer be present in the population if they were present in specific African Americans that are not a part of the New Orleans’s community anymore. Figure 2 demonstrates the New Orleans population by race and ethnicity before and after Katrina. The African American population was the majority racial group and even though a lot of people from that group left the effect is not as large. On the other hand, the Caucasian and Hispanic population grew after Katrina hit and these areas would see a larger change due to the population size being small. A change that could

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