Science of a Superorganism - my article in Bare Essentials

Bare Essentials - A Free Online Magazine Promoting Life Science and Conservation:  Bare Essentials is an open access online journal that has a commitment to spreading scientific literacy along with some snazzy designs/layouts in their articles. The editor of Bare Essentials asked for a contribution on the relationships between the microbiota and evolution. The article, entitled Science of a Superorganism, is downloadable here.

BE has progressive principles that deserve giving a shot out to, including an affiliation with the Australian Zoo Wildlife Warriors, a conservationist organization that was established in 2002 by the late Steve Irwin and his wife Terri Irwin to involve and educate others in the protection of injured, threatened or endangered wildlife. From the Bare Essentials website:

"Beyond our online resources and publication, we help co-ordinate fundraising opportunities for our conservation partners inviting individuals, groups and sponsors to affiliate with and help raise awareness for preservation efforts through our Wildlife Warriors Initiative."

Spotlighting the Stories of the Microbiota: There's so much to say about the microbiota that it was impossible to cover all the work that should be covered; and there are many good articles already out there. My approach was to boil down the basics and shine the lights on the importance of the microbiota for the general audience. I included topics such as how microbes weigh over 5000x more than humans do on the planet, how microbes make you attractive to mosquitoes, how women's hands are microbial dirtier than men's hands, among others.

I also tried to pick up some of the things that my student is studying on gut microbiota and evolution. Here are two more scientific points that are touched upon towards the end of the Bare Essentials piece but dont get much real estate in the article:

1. First, the influence of gut bacteria on animal speciation is one of the major foci of our lab's research. We are studying how changes in the number and types of gut bacteria change during the process of animal speciation, and how the gut bacterial community may in fact cause speciation events by reducing interbreeding between two animal species. Recently we published a paper in the journal Evolution in which we showed that gut bacteria in closely related species of insects, Nasonia parasitoid wasps, increases in diversity over development from larvae to pupae and adults. The gut bacteria essentially becomes more diverse by colonization of new bacterial types as the insects develop, similar to what happens within humans in which an infant rapidly accumulates different species of bacteria over the course of their first year. 
2. We also test whether diet or animal genes have a more important impact on the composition of the types and abundance of bacterial species in their guts. If diet affects the gut microbiota, then by rearing closely related species on the same diet, the null hypothesis would be that all three species harbor the same types of bacteria. We did not observe this. Instead, what we observed is that when the Nasonia wasps were reared on the same diet (fleshfly hosts), the bacterial communities became slightly different in each of the wasp species; and the relationships of these slightly different gut communities between the Nasonia species parallels the relationships of the Nasonia chromosomal genes (see conceptual figure below based on findings in the Evolution paper). Therefore, we conclude that bacterial communities diverge in parallel with the wasp's genes over evolutionary time-frames that span the formation of new species. The implications are significant. In particular, a host's bacterial population is not transient or unstable. Instead, it is species-specific at some levels and likely selected for by the immune system to perform functions within the host that may be slightly different from the functions in closely-related host species. What happens to these bacterial communities in hybrids and how the bacteria affect hybrid problems such as mortality between Nasonia species is what we currently have our heads buried in.

The figure above by Robert Brucker and I shows the codivergence between the genes of the wasp on the left and their gut microbial communities on the right. The three Nasonia species differ in their wing sizes and the fleshfly host on the bottom is Sarcophaga bullata. The bolded colors on the circular trees indicate the different types of bacterial species present in the insects.