As regular readers of The Daily Ant know already, ants harbor lots of bacteria. A growing number of studies are revealing that we should investigate these microbial communities, and their associations with their hosts, in order to fully understand the ecology and evolution of ants. In pursuit of this goal, Manuela Ramalho and colleagues just published an interesting study on the microbial composition of one of the coolest ant groups – Polyrhachis, the spiny ants.

Polyrhachis ant, with its microbial community. Photo: Melvyn Yeo

The researchers used high-throughput sequencing methods to obtain DNA from the bacteria of over 80 species of spiny ants. Then, they tested for correlations between the bacterial communities and the geography and phylogenetic relationships of the ants. One particular question of interest for the researchers was whether or not the ant species’ phylogenetic relationships followed that of the bacteria species (technically “operational taxonomic units”, or OTUs, because distinguishing bacterial species is hard!).

Ramalho and colleagues found that the bacteria in spiny ants do not appear to be generally associated with geography. That is, across the geographic range of different ant species, the bacterial community hosted by the ants did not seem to vary in any consistent way. However, they did find some evidence of coevolution – some bacterial groups were more common in some ant species groups than others. These broad patterns suggest that the diversification of spiny ants have impacted bacterial diversification and vice versa. Furthermore, any geographical associations with the bacterial communities are apparently too complex to be detected by straightforward correlation analyses.

In conclusion, Happy Passover!

Editor’s Note: The first author of this study, Manuela Ramalho, is a former lab colleague of our editor-in-chief. Also, a co-author, Corrie Moreau, is the PhD advisor of our editor-in-chief.