BILD 3 Chapter Notes - Chapter 21: Natural Selection 2, Allele Frequency, Dna Replication
Document Summary
Microevolution: a change in allele frequencies in a population over generations. 3 main mechanisms that can cause allele frequency change. Differences among individuals in the composition of their genes or other dna sequences. At the whole gene level, it can be quantified as the average percentage of loci that are heterozygous. Can also be measured at the molecular level of dna, but little of this variation results in phenotypic variation because many of the differences occur within introns. Those that do occur on the exons don"t alter the amino acid sequence, so still little variation. Originates when mutation, gene duplication, or other processes produce new alleles and new genes. Can be produced in short periods of time in organisms that reproduce rapidly. New alleles can arise by mutation, a change in the nucleotide sequence of an organism"s. Only mutations in cell lines that produce gametes can be passed to offspring.