page_title: Holobiont
section_title: The holobiont phenotype
hierarchical_section_title: Holobiont / The holobiont phenotype
caption_attribution_description: English: The holobiont phenotype Holobionts are entities comprised of the host and all of its symbiotic microbes, including those which affect the holobiont’s phenotype and have coevolved with the host (blue), those which affect the holobiont’s phenotype but have not coevolved with the host (red), and those which do not affect the holobiont’s phenotype at all (gray). Microbes may be transmitted vertically or horizontally, may be acquired from the environment, and can be constant or inconstant in the host. Therefore, holobiont phenotypes can change in time and space as microbes come into and out of the holobiont. Microbes in the environment are not part of the holobiont (white). Hologenomes then encompass the genomes of the host and all of its microbes at any given time point, with individual genomes and genes falling into the same three functional categories of blue, red, and gray. Holobionts and hologenomes are entities, whereas coevolution or the evolution of host-symbiont interactions are processes.
context_page_description: A holobiont is an assemblage of a host and the many other species living in or around it, which together form a discrete ecological unit. The components of a holobiont are individual species or bionts, while the combined genome of all bionts is the hologenome. The concept of the holobiont was initially defined by Dr. Lynn Margulis in her 1991 book Symbiosis as a Source of Evolutionary Innovation, though the concept has subsequently evolved since the original definition. Holobionts include the host, virome, microbiome, and other members, all of which contribute in some way to the function of the whole. Well-studied holobionts include reef-building corals and humans.
  There is controversy over whether holobionts can be viewed as single evolutionary units.
context_section_description: Holobionts are entities composed of a host and all of its symbiotic microbes.
  In the diagram, the symbiotic microbes that affect a holobiont's phenotype and have coevolved with the host are coloured blue, while those which affect the holobiont’s phenotype but have not coevolved with the host are coloured red. Those that do not affect the holobiont’s phenotype at all are coloured gray. Microbes may be transmitted vertically or horizontally, may be acquired from the environment, and can be constant or inconstant in the host.
  It follows that holobiont phenotypes can change in time and space as microbes come into and out of the holobiont. Microbes in the environment are not part of the holobiont (white). Hologenomes then encompass the genomes of the host and all of its microbes at any given time point, with individual genomes and genes falling into the same three functional categories of blue, red, and gray. Holobionts and hologenomes are entities, whereas coevolution or the evolution of host-symbiont interactions are processes.
caption: The holobiont phenotype [2]
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