Otani S.,Center for Social Evolution |
Mikaelyan A.,Max Planck Institute for Terrestrial Microbiology |
Nobre T.,Wageningen University |
Nobre T.,University of Évora |
And 8 more authors.
Molecular Ecology | Year: 2014
Gut microbes play a crucial role in decomposing lignocellulose to fuel termite societies, with protists in the lower termites and prokaryotes in the higher termites providing these services. However, a single basal subfamily of the higher termites, the Macrotermitinae, also domesticated a plant biomass-degrading fungus (Termitomyces), and how this symbiont acquisition has affected the fungus-growing termite gut microbiota has remained unclear. The objective of our study was to compare the intestinal bacterial communities of five genera (nine species) of fungus-growing termites to establish whether or not an ancestral core microbiota has been maintained and characterizes extant lineages. Using 454-pyrosequencing of the 16S rRNA gene, we show that gut communities have representatives of 26 bacterial phyla and are dominated by Firmicutes, Bacteroidetes, Spirochaetes, Proteobacteria and Synergistetes. A set of 42 genus-level taxa was present in all termite species and accounted for 56-68% of the species-specific reads. Gut communities of termites from the same genus were more similar than distantly related species, suggesting that phylogenetic ancestry matters, possibly in connection with specific termite genus-level ecological niches. Finally, we show that gut communities of fungus-growing termites are similar to cockroaches, both at the bacterial phylum level and in a comparison of the core Macrotermitinae taxa abundances with representative cockroach, lower termite and higher nonfungus-growing termites. These results suggest that the obligate association with Termitomyces has forced the bacterial gut communities of the fungus-growing termites towards a relatively uniform composition with higher similarity to their omnivorous relatives than to more closely related termites. © 2014 John Wiley & Sons Ltd.
Dijkstra M.B.,Center for Social Evolution |
van Zweden J.S.,Center for Social Evolution |
Dirchsen M.,Center for Social Evolution |
Boomsma J.J.,Center for Social Evolution
Animal Behaviour | Year: 2010
Nonreproductive workers of many eusocial Hymenoptera 'police' the colony, that is, they attack reproductive sister workers or destroy their eggs (unfertilized; developing into haploid males). Several ultimate causes of policing have been proposed, including (1) an increase in colony productivity, applicable if reproductive workers work less, or (2) an increase in worker-to-male relatedness, applicable if within-colony relatedness is low. To explain the distribution of policing across taxa, the explanatory power of these and other potential ultimate causes should be assessed separately. One of the few species for which this can be done is the leafcutter ant Acromyrmex echinatior. We previously demonstrated that colony productivity incentives (and sex ratio incentives) are minimal here, while relatedness incentives are strong because queens are highly multiply mated. Overcoming technical difficulties peculiar to leafcutter ants, we introduced reproductive versus nonreproductive workers and batches of queen-laid versus worker-laid eggs into experimental colony fragments and observed their fate. Our main finding was that workers policed by selectively destroying worker-laid eggs, but without attacking reproductive workers. We infer that relatedness incentives are the most likely ultimate cause of the evolutionary maintenance of worker-egg policing in A. echinatior. © 2010 The Association for the Study of Animal Behaviour.