Effects of Wolbachia on social traits and fitness in pharaoh ants
Rohini Singh, Rohini Singh , Timothy A. Linksvayer
Department of Biology, University of Pennsylvania, Philadelphia, PA, USA; Department of Biology, University of Pennsylvania, Philadelphia, PA, USA ; Department of Biology, University of Pennsylvania, Philadelphia, PA, USA
Symbiotic microbes are highly prevalent, from insect to human hosts, and are well integrated with their host’s machinery affecting their behavior and physiology. Wolbachia, a maternally inherited group of bacteria, are widely documented to affect the reproductive behaviour, ecology and evolution of their insect hosts. Use of model organisms like Drosophila and Nasonia have provided insights into mechanisms of inheritance, action and consequences of Wolbachia infection on its host’s fitness. However, due to the solitary nature of these organisms there are limited insights into the effect of Wolbachia on multiple social interactions. Eusocial model systems like, pharaoh ants (Monomorium pharaonis), help overcome this limitation. We, for the first time, have identified social and fitness consequences of Wolbachia in pharaoh ant colonies. Wolbachia infection affects total eggs laid by the ant queens, ant colonies’ net productivity and reproductive investment. The trend of these effects are a function of the queens' age. Wolbachia seems to be regulating the life history strategies in pharaoh ants. Younger infected queens, in comparison to uninfected queens, invest more in reproduction and increased net productivity. However, their reproductive output declines faster as they age compared to uninfected queens, which seem to follow a 'slow and steady' life history strategy. Using a series of experiments, we have characterized the fitness effects of Wolbachia infection in a social organism, providing information about its possible effects and functions which have been missing in the field.