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Can Microbes Drive Speciation?

Is it possible that different microbes in the gut of one species could, over time, lead to the split of that organism into two distinct species.

If microbe-driven speciation is possible then it would make for a novel twist on evolution, and a research team based at Vanderbilt University says that it has happened, in a type of parasitic jewel wasp, Science writes.

The research findings are “important and potentially groundbreaking, University of Rochester biologist John Werren told Science.

“Scientists have studied speciation… for many years, and this opens up a whole new aspect to it.”

Vanderbilt Investigators Seth Bordenstein and Robert Brucker focused their eyes on three species of the parasitic wasps; Nasonia giraulti and N. longicornus, which are closely related, and a third, N. vitripennis, which split off from the other two about a million years ago.

They knew that that most of the offspring that result from the first two species breeding survive, but when N. vitripennis mates with either of them, all of the male larvae in the second generation die off.

They also knew that N. vitripennis has different gut microbes than the other species, and wondered if this was what caused the offspring to fail.

They designed an experiment in which they raised all three species without gut microbes, and found that the second generation of offspring between N. vitripennis and N. giraulti survived. But when they reintroduced bacteria into the same wasps, most of the second generation died again.

Werren says this study gives them a new way to look at speciation. Rather than thinking only about how parents’ genes work together, researchers may want to consider whether the parents’ genomes are compatible with the microbes in their offspring, according to Science.

Bordenstein suggests that the genes found inside microbes within an organism may be as important for evolution. He refers to the genomes of both the host and its microbes as a ‘hologenome’.

Werren says that analysis may be a stretch: "They are not co-evolving as a single unit, so why would we call them a single genome?"