How would a parasitic relationship develop between dominant species?

What sort of circumstances would allow for a parasitic relationship between two dominant species of an Earth-like planet? The criteria for an answer is as follows:

• The relationship must involve no more nor less than 2 separate species
• Both species must be dominant, ie. independent, intelligent and capable of recognition of the existence of the relationship
• The relationship must benefit one of species whilst harming the other
• The relationship must be evident throughout the species, not only in a select sample
• The relationship must be ecologic or biologic, ie. a war between two dominant species, where one species is more advanced and clearly will win, does not qualify

Criteria aside, the question is how would such a relationship naturally develop whilst both species, especially the harmed species, remain dominant. The second point states that both species must be aware of the relationship; if this is not possible, this statement may be omitted.

posted almost 10 years ago

blaizor‭

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