Title: A twelve-step program for evolving multicellularity and a division of labor

Author(s): Kirk DL

Source: BIOESSAYS 27 (3): 299-310 MAR 2005

Abstract: The volvocine algae provide an unrivalled opportunity to explore details of an evolutionary pathway leading from a unicellular ancestor to multicellular organisms with a division of labor between different cell types. Members of this monophyletic group of green flagellates range in complexity from unicellular Chlamydomonas through a series of extant organisms of intermediate size and complexity to Volvox, a genus of spherical organisms that have thousands of cells and a germ-soma division of labor. It is estimated that these organisms all shared a common ancestor about 50 +/- 20 MYA. Here we outline twelve important ways in which the developmental repertoire of an ancestral unicell similar to modern C. reinhardtii was modified to produce first a small colonial organism like Gonium that was capable of swimming directionally, then a sequence of larger organisms (such as Pandorina, Eudorina and Pleodorina) in which there was an increasing tendency to differentiate two cell types, and eventually Volvox carteri with its complete germ-soma division of labor.

Title: The occurrence of a bloom-forming green alga Pleodorina indica (Volvocales) in the downstream reach of the River Malse (Czech Republic)

Author(s): Znachor P, Jezberova J

Source: HYDROBIOLOGIA 541: 221-228 JUN 1 2005

Abstract: In mid-August 2003 a massive bloom of the green alga Pleodorina indica (Iyengar) Nozaki (Volvocales) occurred in the downstream reach of the River Malse in the Czech Republic. An exceptionally long period of the hot dry weather resulted in low flow conditions and warm water temperatures. These environmental conditions combined with high nutrient concentrations led to the macroscopic appearance of P. indica in the form of an extensive surface scum formation with diurnal changes. The alga soon dominated the river phytoplankton, attaining concentrations of 2000 colonies per millilitre. The bloom persisted in the river from the 10-17 August when it was eventually flushed out. P. indica is an indigenous species of tropical climatic regions and prior to this its massive occurrence has not been reported in the temperate region of Central Europe.