Feed two separate groups of fruit flies different food, and the two groups will develop different gut microbiotas tailored to their diet. But according to Prof. Michael Shapira, who teaches integrative biology at the University of California, Berkeley, within one generation, the difference in diet led to the fruit flies exhibiting a mating preference for flies in their own group.
“This led to de facto reproductive isolation of two populations and could facilitate future speciation, that is, real reproductive isolation—a genetic barrier preventing members of the two groups from parenting viable or fertile progeny,” Shapira said in a statement.
In a study slated for publication in Trends in Ecology and Evolution, Shapira reviewed previous examples of the symbiotic relationship between microbiotas and their influence on their hosts’ evolution. This coevolution is well-accepted among the scientific community. “However, the emerging importance of plant- and animal-associated microbiotas in their hosts suggests a scale of co-evolutionary interactions many-fold greater than previously considered,” Shapira wrote in the study, which is available online.
Specifically, Shapira is expanding on the hologenome concept, which was proposed by Ilana Zilber-Rosenberg and Eugene Rosenberg in 2008. Rather than the genomes of the host and microbiota acting separately, the concept says they coalesce.
“During periods of rapid changes in the environment, the diverse microbial symbiont community can aid the holobiont in surviving, multiplying and buying the time necessary for the host genome to evolve,” Zilberg-Rosenberg and Rosenberg wrote in their study. “The distinguishing feature of the hologenome theory is that it considers all of the diverse microbiota associated with the animal or the plant as part of the evolving holobiont.”
Shapira hypothesizes that animals along with a core set of microbiota evolve in tandem. But it’s a separate group of microbiota, a flexible pool, which helps the host adapt to changing environments and diets quickly.
According to U.C. Berkeley, an example of this in action is when the broad-headed stink bug successfully adapted to withstand pesticide. This occurred when it acquired a microbe capable of detoxification.
Shapira, who studies the microbes of the roundworm, plans on testing his hypothesis on roundworms in future experiments.
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