The Volvocine Green Algae diverged from a unicellular Chlamydomonas –like ancestor approximately 240 mya (Herron et al. 2009). They range from simple unicellular species like Chlamydomonas reinhardtii to large complex species with thousands of cells and cellular differentiation, as seen in Volvox carteri. Intermediate forms range from simple sheets of 8-16 cells as seen in Gonium, to larger 32-64 celled spheroids as in Eudorina, and 128 celled spheroids with somatic cells as in Pleodorina. These extant forms are predicted by our character state reconstructions to be similar to evolutionary intermediates during the evolution of multicellular individuality in this lineage.
Dinah Davison
Four volvocine green algae species that exhibit differences in group formation and/or cellular differentiation. A: Unicellular Chlamydomonas reindhardtii CC 124. B: Eudorina elegans UTEX 1201, in which all cells are typically undifferentiated. C: Pleodorina starrii NIES 1362, which possesses both undifferentiated cells and small somatic cells. D: Volvox carteri Eve, which consists of large germ cells and small somatic cells.