Natural Selection - The process by which certain heritable traits that contribute to the survival and reproductive success of an organism become more widespread within a population over successive generations.⏎
Reservoir - An organism in which a parasite that is pathogenic for some other organism lives and reproduces without harming its host.⏎
Nanometer - A unit of length equal to one one-billionth (1 x 10-9) of a meter.⏎
Prion - A causative agent of infectious disease that is composed primarily of protein.⏎