Lecture 15: neodarwinism & the evolutionary significance of genetic variation. Basic terms: genotype: genetic constitution of an organism; used in relation to particular gene or gene combination, genome: entire organisms dna including genes and on-coding regions. Phenotype: organism as observed; used when discussing trait or feature of an organism that varies. Gene: unit of hereditary information located on chromosome consisting of dna, dna sequence composed of codons essential for specific biological function. Codons: sequence of 3 nucleotides that makes up genetic code. Comes from 4 sources: mutation: ultimate source of genetic variation, recombination: more genotypes b/c genes are mixed together, gene flow: movement of genes from one population to another, hybridization - increases genetic variability; interspecies mating. Independent assortment (during meiosis there is possibility of random combination of gametes) & recombination during meiosis generates enormous diversity: most genetic variability in a population results from sexual reproduction; in any given generation input from mutation very small.