TOWARDS MUTUALISM. “In recognition of the more complex interactions between transposable elements and their hosts, Kidwell and Lisch proposed an expansion of the “parasitism” framework where each TE can be classified along a spectrum from parasitism to mutualism.” (TE = transposable elements).
http://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1004351