Intermediate Steps

摘要

Identifying the origin of the prokaryote-eukaryote transition has been a longstanding and contentious issue (7,2) with numerous hypotheses. Over the last decade, "fusion hypotheses" have dominated the field (5). Many of these propose that the fusion of two prokaryotes accounts for the seemingly chimeric nature of the eukaryote gene set. Other theories propose that eukaryotes and archaea shared an ancestor that emerged from a bacterium (4). Thus, eukaryotes may be a mosaicism, combining features (including genes) inherited from a bacterial ancestor with those developed by an archaeal-eukaryotic ancestor before the split between eukaryotes and archaea.