On 1 Mar 1995, Jeffrey Lotz wrote:
>> Even on sematic (rather than empirical) grounds, I would argue
> against the restriction of parasite to pathogen. If we restrict
> the use of parasite to pathogen then we are left without a word
> to apply to organisms that are not-free-living. Typically
> symbiosis is used to encorporate interspecific relationships
> including mutualist-commensal-parasite. However, symbionts
> usually include nest-parasites, cleaner fish, cattle egrets and
> other organisms that live in close association with another
> organism but are essentially free-living. Given this situation
> we need a word that means not-free-living, that world should be
> "parasite". We already have a word for a not-free-living
> organism that does harm to its habitat, that word is pathogen.
I think that removing host damage from the definition of a parasite only
creates more confusion. Mutualism and commensalism involve completely
different life history strategies that follow differnt pathways of
selection . In the case of parasites, harm to the intermediate host is often
required for transmission, a situation that would be untenable for a mutualist.
If you are looking for a word to encompass non-freeliving organisms I
would be happy to lend you "endosymbiont". I know it just adds to the
list of jargon, but I don't think that the term parasite should be
expanded to include commensals and mutualists.
Derek A. Zelmer