Natural Selection- the process whereby organisms better adapted to their environment tend to survive and produce more offspring.
Mutations- Small errors in DNA code during cellular reproductions. (Can be beneficial or harmful)
Migration/Gene Flow- Any movement of individuals and/or the genetic material they carry from 1 population to another. 
Parallel Evolution- Two different species evolve similarly b/c of life style.
Convergent Evolution- Organisms with different ancestors become more alike.
Sexual Selection- Passing on of genetic info, influenced by male competition and female choice. 
Genetic Drift- variation in the relative frequency of different genotypes in a small population, owing to the chance disappearance of particular genes as individuals die or do not reproduce.
Homologous Structure- Parts that are similar in structure but have different uses in different species. 
Vestigial Organs- Structures in some organisms that seem to have no use in one species but are useful in others. 
Ontogeny Recapitulates Phylogeny- Organisms during embryological development go through the evolutionary stages. 
Molecular Evolution- differences in molecular similarities can be used to determine degrees of relationship between different species.