Sentence:  It is likely that the long evolutionary trajectory of "Mycoplasma" went from a reductive autotroph to oxidative heterotroph to a cell-wall–defective degenerate parasite. This evolutionary trajectory assumes the simplicity to complexity route of <WSD>biogenesis</WSD>, a point of view that is not universally accepted. 
Meaning of the word marked with <WSD> tags:  The principle that living organisms are produced only from other living organisms.