Figure 1

The major hypotheses of the basal hexapod relationships proposed in recent studies. (A) Traditional view based on morphology [20, 49]. (B) Based on mitogenomic data [22, 23]. (C) Based on fossil data [32], comparative embryological evidence [33, 34], morphological data [28, 35], and some molecular sequences (EF-1α, EF-2, and RAN polymerase II) [36]. (D) Based on nuclear molecular data [7, 8, 29, 30, 37].