The title is not a grammatical mistake! New research by Bordenstein et al,microbiologists at the Vanderbilt University, which is published in the open access journal PLOS Biology, hint that the individual organism that we see is just the tip of the iceberg, with the legion of microbes within the body and their respective genomes making up the total “microbiome” being significant in virtually all important outcomes, including the origin of new species. Therefore thinking of plants or animals as “individuals” may be an oversimplification.
A series of studies have shown that the way an individual organism develops, the disease it catches, the way it behaves and even perhaps its social interactions are dependant on the millions of microbes that inhabit its body.
Keeping this idea in mind, the authors of the paper, “Host biology in the light of the Microbiome: Ten principles of Holobionts and Hologenomes” list out a set of principles for the study of organisms.
Holobionts here are the collective entities including the organism with its microbiome, and the term “hologenome” refers to the collective genomes. In a press note issued by the university, Dr Bordenstein noted, “One of the basic expectations from this conceptual framework is that animal and plant experiments that do not account for what is happening at the microbiological level will be incomplete, and, in some cases, will be misleading as well.”
How does one develop a science of such a complex entity? The authors put forth ten principles for their study. The first principle is that these two concepts, holobionts and hologenomes, are the fundamental units of biological organisation. Secondly, they say that as the entity evolves as a whole, mutations of the hologenome are as important as mutations of the genome in the organism’s evolution, and forces such as natural selection must act on the hologenome itself. They clarify that while the rules of evolution are still the same, the units on which these rules act will have to be redefined using concepts such as the hologenome and holobiont. Dr Bordstein further added that this powerful holistic approach is likely to impact the practice of personalised medicine as well.