community that functions as if it were a single organism ( [accessed July 27, 2012]).

Symbiont: An organism in a symbiotic relationship. In cases in which a distinction is made between the two interacting organisms, the symbiont is the smaller of the two and is always a beneficiary in the relationship, while the larger organisms is the host and may or may not derive a benefit (American Heritage Science Dictionary. 2011. Houghton Mifflin Harcourt Publishing Company).

Symbiosis: The close association between two or more organisms of different species, often but not necessarily benefiting each member (American Heritage Science Dictionary. 2011. Houghton Mifflin Harcourt Publishing Company).

Tragedy of the commons: A dilemma arising from the situation in which multiple individuals, acting independently and rationally consulting their own self-interest, will ultimately deplete a shared limited resource, even when it is clear that it is not in anyone’s long-term interest for this to happen. This dilemma was described in an article written by ecologist Garrett Hardin and first published in the journal Science in 1968 ( [accessed July 27, 2012]).

tRNase: Abbreviation for transfer ribonuclease. Ribonucleases are a type of enzyme that catalyzes the degradation of RNA into smaller components. Transfer RNA is a RNA that delivers the amino acids necessary for protein synthesis to the ribosomes.

Virus: A small infectious agent that can only replicate inside the cells of another organism. Viruses are too small to be seen directly with a light microscope. Viruses infect all types of organisms, from animals and plants to bacteria and archaea.

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