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• Symbiosis is the coevolved intimate relationship between members of two different species
• types of symbiotic relationships - parasitism and mutualism
• A parasite benefits in terms of energy or nutrients while its host is harmed by the loss of these resources
• Parasites have limited metabolism and cannot survive out of contact with a host
• Transmission of parasites to new hosts using direct contact, resistant stages and vectors
• Some parasitic life cycles involve secondary hosts to allow them to complete their life cycle
• Both mutualistic partner species benefit in an interdependent relationship