Abstract

  The transition from unicellular to multicellular organization is a major step in eukaryotic evolution. In the beginning unicellular organisms ruled the earth. For more than 3 billion years after the appearance of unicellular microbes, life gradually got more complicated. Today, most plants, animals, fungi, and algae are composed of multiple cells that work collaboratively as a single being. But how did life evolve from unicellular simplicity to multicellular complexity? Explanation to this question is one of the major evolutionary puzzles of our time. In this context it can be said that the group behavior of unicellular organisms with better survival advantage is crucial to the development of multicellularity from unicellular life. It is well known that the bacteria, a primitive life form, remaining in groups in biofilm can well protect themselves from antibacterial substances. This group behavior or colonial form found in other unicellular living forms, like charophytes algae, volvocine algae and choanoflagellates led to increasing organismal size which helped in escaping microscopic predators such as ciliates.It may be presumed that after the development of well advanced eukaryotic cell from prokaryote through endosymbiosis, the well organized genetic structure and better information dissipation capability with critical development of cell membrane signaling pathway with better way of keeping intercellular communication, multiple eukaryotic unicellular forms in a collection followed this group behavior for a long time and receiving triggering factors from multiple sources and switching back and forth of their gene expression based on environmental condition, evolved into multicellular eukaryotic form.

Keywords: Group behavior; Endosymbiosis; Cell differentiation; Cell-cell interaction; Biofilm; Ectoderm; Endoderm; Mesoderm

References

1. C Mereschkowsky. “La plante considerée comme un complexe symbiotique Societé des Sciences Naturelles de l’Ouest de la France”. Nante Bulletin 6 (1920): 17-98.
2. J Sapp. Evolution By Association: A History of Symbiosis, Oxford University Press, New York (1994).
3. JM Archibald. One Plus One Equals One: Symbiosis and the Evolution of Complex Life, Oxford University Press (2014).
4. L Margulis. Symbiotic Planet, Basic Books (1998).
5. L Margulis. Origin of Eukaryotic Cells, Yale University Press (1970).
6. Alberts B., et al. “Molecular Biology of the Cell”. 4th edition. New York: Garland Science (2002).
7. James G Umen. “Green Algae and the Origins of Multicellularity in the Plant Kingdom”. Cold Spring Harbor Perspectives in Biology 6 (2014): a0161700.
8. King N., et al. “The genome of the choanoflagellate Monosiga brevicollis and the origin of metazoans”. Nature 451 (2008): 783-788. 
9. Alegado RA and King N. “Bacterial influences on animal origins”. Cold Spring Harbor Perspectives in Biology (2014). 
10. Niklas KJ and Newman SA. “The origins of multicellular organisms”. Evolution and Development 15 (2013): 41-52. 
11. JacobsWP. “Development and regeneration of the algal giant coenocyte Caulerpa”. Annals of the New York Academy of Sciences 175 (1970): 732-748. 
12. Kirk DL. “A twelve-step program for evolving multicellularity and a division of labor”. Bio Essays 27 (2005): 299-310. 

Citation

Citation: Anindya Das. “Group Behavior of Unicellular Organisms for Better Survival Leading to Multi-Cellular Organisms". Acta Scientific Microbiology 3.2 (2020): 54-57.

Copyright

Copyright: © 2020 Anindya Das. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.