microevolution
change in allele frequencies in a pop over genrations, isevolution at its smallest scale
3 mechanism cause allele frequency change:
- Natural selection (adaptation to the environment)
- Genetic drift (chance events alter allele frequencies)
- gene flow (transfer of alleles btw pop)
genetic variation
refers to the differences in genes or other DNA sequences among individuals
population
group of individuals of the same species that live in the same area & interbreed
gene pool
consists of all copies of every allele at every locus in all members of the pop
How to calculate genotype frequencies?
divide # of individuals of e/ genotype by total # of individuals in pop
conditions for Hardy-Weinberg Equilibrium
- no mutations
- random mating
- no natural selection
- extremely large populations size
- no gene flow
3 major factors altering allele frequencies and bring evolutionary change
natural selection, genetic drift, gene flow
adaptive evolution
process in which traits enhance survival or reproduction inc in frequency over time
genetic drift
process in which chance events cause allele frequencies to fluctuate unpreditably from one generation to the next
founder effect
occurs when a few indivudals become isolated from a larger pop
bottleneck effect
occurs when there is a drastic reduction in pop size due to a sudden change in environment
genetic drift summary
- significant in small populations
- cause allele frequencies to change at random
- lead to loss of genetic variation w/i pop
- cause harmful alleles to become fixed
