BIOL 1F90 Lecture Notes - Lecture 23: Sickle-Cell Disease, Allele Frequency, Panmixia
Document Summary
All alleles for every gene in a given population. Groups of individuals from the same species in a certain area. Allele freq: (number of allele copies) / (total number of alleles) Not a major factor dictating allele frequencies. Natural selection: allele variation due to random mutations. 3. some encode proteins that increase odds of survival & reproduction. Individuals with beneficial alleles are more likely to contribute to the gene pool of the next generation: allele shift towards different frequencies after many generation. Directional: favours one direction or the other, but no combination of alleles. Stabilizing: favours intermediate phenotype, extremes are selected against ex. clutch size. Disruptive / diversifying: extremes are more likely to survive ex. Balancing: 2 different alleles are maintained at once. Ex. sickle cells can"t transport oxygen but are resistance to malaria, having both sickle cells and regular blood cells can be advantageous if organism lives in a region with a high risk of malaria.