Siblings near and far: Population genetics of a new Panamanian fungus-growing ant (Formicidae: Attini: Mycetomoellerius)

Panama’s biodiverse rainforests provide fascinating insights into many areas of biology. One group of Panamanian insects, the fungus-growing ants, are well documented for their coevolution and symbiosis with their fungal cultivars and other organisms. Much of what has been learned comes from over 60 studies focusing on Mycetomoellerius sp. nov. This species is coevolving with a network of interacting species ranging from mutualistic microbes to social parasites and parasitoids. Despite all these discoveries, no one has studied the population ecology of this remarkable host. With the rich symbiotic network in mind, we explore the population structure of Mycetomoellerius sp. nov. in the Panama Canal zone. We ask if there are distinct genetic populations and if geographic features (i.e. creeks or rivers) act as a barrier to gene flow. To accomplish this, we genotyped 85 colonies from nine creeks across ca. 30 km using double digest restriction-site associated DNA sequencing. We generated 1,133 unlinked neutral SNP’s and analyzed them using population statistics and models, while testing the relatedness of colonies. We found many sibling colonies on the same creek and at further geographic distances. This evidence suggests that colonies tend to be established on natal creeks and dispersal events contribute to the observed panmictic population and isolation by distance. This pattern could be a result of range expansion or of historic land disturbances like reforestation in the canal zone. Understanding the population genetic processes of a well-studied species provides valuable context for the evolutionary relationships already identified in fungus growing ants.