Learn a lot via rapidly evolving organisms such as viruses. Evolution: the change in genetic composition of populations over time. Evolutionary theory- understanding biological changes of evolution. Species are not immutable- they change over time. Divergent species share a common ancestor (descent with modification) Changes in species over time can be explained by natural selection- variation in traits (more species are born than survive to reproduce) A population evolves when individuals with different genotypes survive or reproduce at different rates. Gene pool: sum of all copies of all alleles at all loci in a population. Evolution is the change in proportion of alleles. Evolution- changes in the genetic makeup of a population over time. A group of individuals of a single species living together in a geographical area and interbreeding. Natural selection, mutation, gene flow, genetic drift, mating (5) Any change in the nucleotide sequence of dna. Natural selection results in adaptation: a favoured trait that evolves through natural selection.