BIO 115 Lecture Notes - Lecture 19: Natural Selection, Zygosity, Genetic Drift
Document Summary
Alleles that lower fitness experience negative selection. Alleles that increase fitness experience positive selection. They took survivors and moved them to new flasks each day. Result: bacteria became more fit in low glucose than the original ancestor. Evolution occurs by mutation and natural selection. Additive: allele yields twice the phenotypic effect when two copies present especially vulnerable to selection. Dominance: dominant allele masks presence of recessive in heterozygote. Heterozygous most common form of the allele in the environment. Effects of selection on different types of alleles. Particular effect on how selection effects on an allele in a population. Probability of fixation of a particular type of allele that have different relationships with the alternate alleles. Frequency of the population, where 100% is fixed at the particular locus. In this graph, all the alleles go towards fixation, but only additive and recessive reach full fixation. In this given time period, the dominant allele does not reach fixation.
