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Expanding Evolution to the Microbiome

Expanding Evolution to the Microbiome

The microbes of an organism could affect the evolution of a new species.

This is an illustration of the tree of life created in microbial culture. Credit: Robert Brucker, Vanderbilt University

This is an illustration of the tree of life created in microbial culture. Credit: Robert Brucker, Vanderbilt University

It is now said that humans should be considered a “super-organism” because we have our own cells and trillions of microbial cells we are symbiotic with. Recently, much intense study has focused on this microbiome, demonstrating that the bacteria and other organisms that live in our gut, on our skin, and throughout the rest of our body can influence our health. Now a recent study from Vanderbilt University has suggested that these microbes may also affect evolution. Because really, humans are not unique in this attribute, as almost all complex organisms have an associated microbial community living in them or on them.

The idea that evolution would not only act upon the individuals of a species, but the species and its microbiome is called the hologenomic theory of evolution, and is still controversial. However, this recent study is the first to suggest that the microbes of an organism could affect the evolution of a new species. To test this and they created hybrids between three species of jewel wasp (genus Nasonia). Two of these species were closely related genetically and in the composition of their microbiome, whereas the third had diverged from the other species evolutionarily almost a million years ago. Hybrids between the two closely related species had extremely low survival rates, and an extremely chaotic microbiome. Whereas both sets of hybrids with the more distantly related species had extremely high survival rates and microbes more similar to that of their parents.

While new species are not generally formed by hybridization, this did demonstrate that the viability of offspring can be greatly influenced by the microbiome of its parents. When all of the wasp hybrids were grown in a germ-free environment the normally unsuccessful hybrids survived. That is until they were reintroduced to the chaotic mix of gut microbes that were found in the first set of closely related hybrids. With this first observed example of hologenomics at work, more research will be needed to see how common the microbiome may affect evolution.

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Reference: Robert M. Brucker and Seth R. Bordenstein (2013). The Hologenomic Basis of Speciation: Gut Bacteria Cause Hybrid Lethality in the Genus Nasonia Science

microbes evolution, microbiome evolution, bacteria evolution

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