Figure 4From: Hybrid male sterility between Drosophila willistoni species is caused by male failure to transfer sperm during copulationMorphology of the A) male external and B) male internal (aedeagus) genitalia of D. w. willistoni, D. w. quechua, F1WQ (fertile) and F1QW (sterile) hybrids are shown clockwise from top left.Back to article page