Normally, when members of two related species of parasitic wasps in the genus Nasonia, N. giraulti and N. longicornis, mate with their more distant relative N. vitripennis, the hybrid offspring die. Until recently, no one could figure out exactly why, but it was clear that this was one of the major barriers dividing the species. But when Bordenstein and Brucker treated the wasps with antibiotics, eliminating the millions of microbes that lived on their bodies, they found that many of the hybrid offspring unexpectedly could survive and thrive. By stripping off the wasps’ microbiomes — the microbial community inhabiting the insects — Bordenstein and Brucker had brought a totally new hybrid wasp to life.
The findings, published in Science in July 2013, highlight a surprising idea in biology: that symbiosis — a long-term, stable and often beneficial interaction between organisms — could drive two populations apart, the first step in the development of new species.