BIO152H5 Lecture Notes - Lecture 13: Escherichia Coli, Population Bottleneck, Genetic Drift
Document Summary
Increase genetic diversity; create/add new alleles into the population. Cause random changes in genes: can be neutral, but many result in deleterious alleles (alleles that lower fitness e. g. sick cell anemia) Can produce a beneficial allele that increases in frequency in a population due to natural selection. Especially important in prokaryotes b/c fast generation time (binary fission, etc. ) Relative fitness: increased over time in jumps ( each jump was a novel mutation); new mutations conferred a fitness benefit. Mutation is the ultimate source of genetic variation. Mutation/variation has to be present for natural selection to work on. Most pronounced in small populations b/c their genetic info vs a larger pop. will have a bigger chance of seeing a difference in the pop since it is so small. Chance events: loss of alleles in small population. Bottleneck effect: sudden decrease in pop size. Founder effect: small group of individuals establishes a pop. in a new location.
