competition: interaction in which organisms of the same or different species attempt to use the same
ecological resource in the same place at the same time.
mutalism: symbiotic relationship in which both species benefit from the relationship.
Predation: interaction in which one organism captures and feeds on another organism.
Parasitism: one organism, the parasite, benefits at the expense of the other, the host
Humans may cause the sixth major extinction. Biologists estimate that the extinction rate for species is 100 to 1,000 times greater than normal "background" extinction due to human interference. Humans impact species in numerous ways. This includes spreading diseases, destroying habitats, hunting animals to extinction or introducing alien species into new environments. Harvard biologist Edward O. Wilson estimated that as many as 30,000 species go extinct every year.
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