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What is microevolution ?
The change in allele frequencies that occurs over time in a population
List the 5 agents of evolutionary change
1- Mutation
2- Non-random mating
3- Gene flow
4- Selection
5- Genetic drift
Explain why mutations are necessary
There must be genetic variation for a population to evolve. The ultimate source of genetic variation is by mutation which creates new alleles
Explain why gene flow in necessary for evolutionary change ?
Alleles must be spread throughout a population to combine with other alleles and create mutations
Why is non-random mating important ?
Because it affects how the alleles spread throughout a population. Individuals will chose mates with preferential traits therefor these traits will get spread more.
Why is selection important ? What are the three types ? Briefly explain each
Selection favours individuals with advantageous traits. Stabilizing: The average trait/ phenotype is preferred
Directional: The extreme phenotype is preferred
Diversifying: Both extreme phenotypes are preferred ( for different reasons/areas)
Why is genetic drift important ? What are the two kinds ?
Because it leads to the loss or fixation of certain alleles which alters the genetic makeup of a population over time.
Bottleneck: Only 1 polymorph survives a natural disaster
Founder effect: Few individuals from an original population start a new population with a different allele frequency
Give an example of the heterozygote advantage in humans ?
Sickle cell anemia;
HH= not resistant to malaria
Hh= resistant to malaria
hh=sickle cell disease
