Conservation Science

Population genetics of army ants and associates

This project is set up to further assess the population genetics of neotropical Eciton army ants and that of their associates.

Army ants within the Eciton genus are top predators and a key element for the maintenance of biodiversity in neotropical forests; with more than 557 species already reported to depend on Eciton burchellii colonies for their survival.  Among E. burchellii associates we find an array of invertebrate and vertebrate species, including mites feeding on ant secretions and hemolymph; flies feeding on the ants refuse; beetles stealing prey or predating the ants or their brood; the iconic army ant that feed on the prey flushed during ant swarming raids; butterflies feeding of army ant following faeces, and subterranean blind snakes that follow ant trails to their temporary nests (bivouacs).

A previous landscape genetics study assessing the effect of landscape features on the gene flow of E. burchellii in the Canal Zone of Panama revealed that the influence of the landscape features reflected the aerial dispersal of the males and the pedestrian dispersal of females and the historical effect of these landscapes. Deforestation was found to be a strong barrier for genetic exchange between colonies; in contrast, mature forests were found to facilitate gene flow among colonies. Interaction analyses between landscape features revealed that other types of forest could also act as gene flow facilitators, but only when near mature secondary forests. Analyses of mitochondrial data identified the River Chagres as a major historical gene flow barrier for E. burchellii colonies in the study area.

The interactions between Eciton army ants and their associates offer captivating examples of evolution of biological diversity. One of these is staphylinid beetles within the genus Ecitomorpha and Ecitophya that have evolved to mimic the appearance and colour of their Eciton host worker cast. Our evolutionary and population genetic studies of Ecitomorpha and Ecitophya beetles found with Eciton colonies in Panama indicated that speciation patterns of these beetles were congruent with specialization to a particular Eciton host; i.e. each Eciton species harbour a particular Ecitomorpha and Ecitophya species. Further population genetics analyses revealed a higher dispersal ability of the associates than the hosts, with gene flow within each beetle species between colonies across the River Chagres.

We are currently conducting population genetic studies of Eciton hamatum, a more common Eciton species in Panama and characterised by its column raids, and we there is scope to conduct a more detail population genetics analyses of Ecitomorpha and Ecitophya beetles using neutrally evolving markers and to expand the area of study beyond Panama.  Please contact Dr Sílvia Pérez-Espona for further information.