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

✍ Scribed by David L. Kirk

• Book ID: 101706873
• Publisher: John Wiley and Sons
• Year: 2005
• Tongue: English
• Weight: 409 KB
• Volume: 27
• Category: Article
• ISSN: 0265-9247
• DOI: 10.1002/bies.20197

✦ Synopsis

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.