Evolutionary Forces Flashcards
What are the principles of mutation?
-creates variation
-makes small changes in allele frequencies
-weak evolutionary force
-some mutations can have a large impact on phenotype due to selection
Random Genetic Drift
-allele frequencies change due to chance
-makes isolated populations genetically different
What is fixation?
-when an allele/variant is lost
-frequency of the allele becomes 100%
What is the relationship btw RGD & population?
-Magnitude is inversely proportional to the population
-smaller population leads to quicker fixation
What evolutionary force is being imposed and defined?
The founder effect, when a small # of people leave a bigger population to move to another location
What is gene flow(migration)
-keeps population similar
-counteracts genetic drift
-increases genetic variability
What effect is being shown?
the effect of gene flow, over time the 2 populations are more genetically similar
Natural Selection
-some genotypes leave more offspring than others
-it measures fitness(reproductive success)
How does directional selection work?
The speed of the change is dependent on the mode of expression & starting allele frequency
What type of natural selection is shown?
Disruptive, Extreme forms are favoured resulting in distinct phenotypes over time
What is stabilising selection?
-extreme forms are selected against resulting over time in phenotypes around population mean
What is balancing selection(heterozygote advantage)
-heterozygote selection provides protection against certain diseases
Selection Balance
- Mutation continually produces new alleles
- Selection removes alleles that are non-advantageous
What happens in the absence of evolutionary forces?
-The allele frequency remains constant from generation to generation
The Hardy-Weinberg Law
-Deviations from this relationship indicate the presence of evolutionary forces
The Hardy-Weinberg Law
p2 + 2pq + q2 = 1 == (p+q)2 = 1
