Seth R. Bordenstein and Kevin R. Theis’s “Host Biology in Light of the Microbiome: Ten Principles of Holobionts and Hologenomes” combines impressive qualities. It suggests no less than a holistic redefinition of zoology, botany, and biology. And they are careful to re-state historical achievements of Darwin, Mendel and modern scientists in this new framework; animals and plants are more appropriately understood as a mutli-species association than autonomous individuals. Both at biologic and genetic level.
As a sense of justice welcome the new status of our former ‘junior’ associates, I wonder how the implosion of the self into a multitude of beings fits well in a society that may overvalue individuality. Instead of a dissolution of the self into a common spirituality, we see the multiplication of ‘I’ into multiple individuals. The untold story of mitochondria et alii paints egocentric narrative in a more altruist light.
This does not take the great service such reconstruction may do to science. Excerpts below:
“At the end of the 19th century, the theory of evolution via natural selection was birthed with the appreciation that individual animals and plants vary in their phenotypes and that competition at the individual level drives gradual change in the frequencies of these phenotypes . From this early vantage point, fusing evolution with Mendelian genetics in the early 20th century was a seamless transition in biology, namely one based on the framework that phenotypes in the individual animal and plant are encoded by the nuclear genome under the laws of Mendelian inheritance [3–5]. In the mid-20th century, the modern synthesis grounded the nucleocentric foundation of zoology and botany in three areas: (1) the nuclear mutability and recombinogenic nature of organisms, (2) the sorting of this genetic variation by natural selection, and (3) the observations that macroevolutionary processes such as the origin of species can be explained in a manner that aligns with Mendelian genetics and microevolutionary mechanisms .
The foundation of the modern synthesis remains as scientifically sound today as when it was conceived. However, it is critical to recognize that microbiology was largely divorced from these early epochs in the life sciences. (…)
Today, there is an unmistakable transformation happening in the way that life is comprehended [12–16], and it is as significant for many biologists as the modern synthesis. Animals and plants are no longer viewed as autonomous entities, but rather as “holobionts” , composed of the host plus all of its symbiotic microbes (…)
This revelation brings forth several newly appreciated facets of the life sciences, including the testable derivation that the nuclear genome, organelles, and microbiome of holobionts comprise a hologenome (…) a holistic view of genetics in which animals and plants are polygenomic entities. (…)
The object of this essay is to make the holobiont and hologenome concepts widely known. We clarify and append what they are and are not, explain how they are both consistent with and extend existing theory in ecology and evolutionary biology, and provide a predictive framework for evaluating them. Our goal is to provide the main conceptual foundation for future hypothesis-driven research that unifies perceived divisions among subdisciplines of biology (e.g., zoology, botany, and microbiology) and advances the postmodern synthesis that we are now experiencing (…)
The Ten Principles of Holobionts and Their Hologenomes
I. Holobionts and hologenomes are units of biological organization (…)
II. Holobionts and hologenomes are not organ systems, superorganisms, or metagenomes (…)
III. The hologenome is a comprehensive gene system (…)
IV. The hologenome concept reboots elements of Lamarckian evolution (…)
V. Hologenomic variation integrates all mechanisms of mutation (…)
VI. Hologenomic evolution is most easily understood by equating a gene in the nuclear genome to a microbe in the microbiome (…)
VII. The hologenome concept fits squarely into genetics and accommodates multilevel selection theory (…)
VIII. The hologenome is shaped by selection and neutrality (…)
IX. Hologenomic speciation blends genetics and symbiosis (…)
X. Holobionts and their hologenomes do not change the rules of evolutionary biology (…)
Hologenome Concept of Evolution
(…) Via fidelity of transmission from parents to offspring or stable acquisition of the microbiome from the environment, (…) phenotypes encoded by nuclear genomes, phenotypes encoded by beneficial, deleterious, and neutral microbes in the microbiome are subject to selection and drift within holobiont populations. (…)
Animal and plant species do not arise exclusively from divergence in their nuclear genomes (…) a combinatorial nature of hologenomic speciation is a far more accurate vision of speciation than has been traditionally recognized (…)
At a time when symbiotic microbes are recognized as fundamental to nearly all aspects of animal and plant biology, the holobiont and hologenome concepts afford holistic, eyes-up views of the multicellular eukaryotic world that are consistent with the generally reductionist approaches of evolutionary biology. Rather than transforming evolutionary thought, the hologenome concept develops it in a substantive and timely way. From a specific standpoint, the holobiont and hologenome concepts redefine that which constitutes an individual animal or plant by asserting that hosts and their symbiotic microbes are complex units of biological organization upon which ecology and evolution can act. (…)
Like all good scientific theories, the concepts are subject to refutation, and in this essay, we have explained how they can be empirically and experimentally falsified. We anticipate that the conceptual foundation provided in this essay will serve as a roadmap for hypothesis-driven, experimentally validated research on holobionts and their hologenomes.”