Genetic Drift and Gene Flow

Genetic drift- random changes in the gene pool that is not influenced by fitness

EX. Driftworm simulation, a random color of worm became fixed, usually takes less than 20 generations to do so

EXAMPLE (founders effect)

amish immigrants in 1800s. around 300 immigrants started the amish population. genetic disorders like polydactylism (six fingers), limb dwarfism, and certain heart conditions have a higher percentage in the amish population then in the original german population they came fro,

Two Conclusions

1. a random variant can become fixed in a population

2. which usually happens to small populations

   could be bad affect or good. usually lower fitness alleles have a higher percentage in the population

Bottleneck Effect

• large population at start

• something happens that kills off most of the population randomly (like a natural disaster)

• usually lose variants as a result

• gene pool changes among surviving variants

• genetic drift is now more likely since it is a smaller population

Founder’s Effect

• large mainland population, some of the population moves somewhere like a pop up island

• the gene pool is different in the new population than the starting

Gene Flow

• happens when populations are separated geographically into subpopulations

• new variation gets introduced into a subpopulation

• movement of individuals between subpopulations and carry their genes around

• gene pools become more similar between populations (Homogenization)

EXAMPLE

people live on different continents, people start to immigrate to different places and mix their genes