BIO120H1 Lecture Notes - Lecture 5: Genetic Drift, Selective Breeding, Neo-Darwinism

• School: UTSG
• Department: Biology
• Course: BIO120H1
• Professor: Spencer C H Barrett

Document Summary

The history of population genetics started with fisher, haldane and wright. Did the mathematics to show why genetic variability was important. A harmonization of population genetics with darwinian natural selection -> (cid:272)o(cid:374)siste(cid:374)t (cid:449)ith me(cid:374)del(cid:859)s la(cid:449)s and brought these laws into our understanding of natural selection. Proportion of gene loci that are polymorphic (variable more than one type of allele: heterozygosity (h) Average frequency of heterozygous individuals per gene locus. Mutation (increase diversity: ultimate source of genetic variation, caused by random errors during replication. Introduces new combinations of mutations into a population: occurs through meiosis. Random genetic drift (decrease diversity: random sampling effects every generation, drift important when populations become small (lose genetic diversity) b/c of environmental catastrophes. Natural selection (can increase and decrease diversity: purifying (negative) selection. Mutations that reduce fitness removed by selection: positive selection (adaptation) Allele will replace what was the wild type allele and will become the new wild type: balancing selection.