Fig. 8

Volvox and volvocine algae. a Cladogram of selected volvocine species shown in cartoon form with successive cellular and developmental innovations indicated by bulleted descriptions above or below the node in which they arose. Species with published sequenced genomes have names in blue-shaded boxes. b–e Light micrographs of vegetative phase Volvox carteri (Volvox) showing a mature pre-cleavage stage adult (b); a mother spheroid with juveniles (c); and an isolated gonidium (d) or somatic cell (e) from a mature pre-cleavage adult spheroid. f Light micrograph of a Chlamydomonas reinhardtii cell. g Schematic of the Volvox vegetative life cycle synchronized to a 48-h diurnal cycle. A boxed key showing cell types and extracellular matrix (ECM) is in the upper left. Development starts with mature pre-cleavage adults (~11:00 on diagram) and proceeds clock-wise through embryogenesis, cyto-differentiation of germ cells (gonidia) and somatic cells in juveniles, hatching of juveniles, and maturation to become the next generation of adults. After hatching the ECM and parental somatic cells of the previous generation are discarded. The cartooned stages corresponding to light micrographs in panels b and c are labeled