Skip to main content
Fig. 6 | BMC Evolutionary Biology

Fig. 6

From: Embryogenesis of flattened colonies implies the innovation required for the evolution of spheroidal colonies in volvocine green algae

Fig. 6

Schematic diagrams of the most likely evolutionary pathways of embryogenesis in volvocine green algae. Diagrams of stages of embryogenesis in Astrephomene and Volvocaceae (Eudorina) shown are based on a previous study [7], while those in Tetrabaena and Gonium are based on the present study (summarized in Additional file 6: Figure S5). Volvocacean species undergo the formation of acute chloroplast ends of daughter protoplasts, which is one of the principal factors producing the force for folding the cell layer during inversion after successive cell divisions. On the other hand, Astrephomene undergoes rotation of daughter protoplasts during successive cell divisions to form a spheroidal shape of the cell layer. Neither Gonium nor Tetrabaena showed the formation of acute chloroplast ends of daughter protoplasts after successive cell divisions or the rotation of daughter protoplasts during successive cell divisions. These results suggest that the ancestor of Astrephomene developed the rotation of daughter protoplasts after it diverged from the ancestors of Gonium, while the ancestor of Volvocaceae acquired the formation of acute chloroplast ends after it diverged from the ancestors of Goniaceae

Back to article page