BIOL 2200 Chapter Notes - Chapter 23: Allele Frequency, Genetic Drift, Genetic Variation
25 Jan 2017
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Evolutions acts on a population; natural selection acts on individuals: ex. A population of medium ground finches lives on one of the galapagos islands. The island suffered from a drought and only 180 birds from the population survived. There were more hard and big seeds than small and soft seeds during the drought, so finches with larger beaks had more food than birds with smaller beaks. As a result the population evolved to include a higher number of larger beaked birds because that trait ensured better survival. Microevolution change in allele frequencies in a population over generations. What causes allele frequency change: natural selection, genetic drift (chance events that alter allele frequencies, gene flow (transfer of alleles between populations) Mendel proposed model inheritance in which organisms transmit heritable units (gene) to their offspring. Genetic variation difference among individuals in composition of genes/ dna sequences: humans vary in their characteristics (hair, blood type, measured on whole gene level (gene variability)
