a change in organisms over time (i.e., descendants are slightly different from ancestors)
founder effect
a type of genetic drift that occurs when only a small number of individuals from a population are present at the establishment ("founding") of a new population
Gene Frequency
the percentage of one allele out of all alleles for that particualr gene in a population
Gene Flow
exchange of genes by migration between populations
gene pool
the total number of alleles for a specific gene in a population
genetic drift
random changes in gene frequency due to sampling error
genetic equilibrium
the condition in which all assumptions of the Hardy-Weinberg Law are met and gene frequencies do not change over time
Hardy-Weinberg Law
gene frequencies do not change over time as a consequence of gentic recombinations during sexual reproduction (provided certain critical assumptions are met)
natural selection
non-random and differential survival of indivudals in a population due to favorable conditions in the survivors
population bottleneck
a type of genetic drift in which population size is sharply reduced due to some catastrophic event