A Test of Emery’s Rule: Ultimate causes of host specificity in a facultative ‘slave-making’ ant
Kelsey Scheckel, Kelsey Scheckel
University of California Berkeley, USA; University of California Berkeley, USA
Chemical recognition systems in Hymenoptera maintain the strict boundaries that define eusocial colonies. Individuals can use these compounds to discriminate between nest mates and non-nest mates so that altruism is directed appropriately at colony members. This allows a colony to guard against ‘cheaters’ that would otherwise exploit the wealth of resources that a social society provides. Despite these efforts, social parasites have evolved a suite of strategies for hacking the chemical cues of their hosts. Slave-making ants raid and capture the pupae of their ant host species and rear these stolen individuals into adult, host workers that will contribute labor to the parasitic nest. Formica aserva is one of the Nearctic facultative slave-making ants found across North America. The host specific relationships of this parasitic species are woefully understudied and questions still remain regarding the similarities, both genetic and chemical, of F. aserva and its hosts. The evolutionary origins of social parasites have long been tested using Emery’s rule, which states that social parasites are close relatives of their hosts. To test this rule, I constructed a gene tree representing the relationship of Formica species relative to F. aserva from a local, geographic range. To further examine these relationships, I used chemical characters to map Formica species relatedness. Since parasites must use some chemical deception strategy to exploit their host, it is likely that the chemical recognition compounds used by F. aserva have evolved similarities with host-specific compounds. In this poster I will present the results of these constructed relationships as they pertain to the host specificity of Formica aserva. Based on these findings, I will conclude whether or not facultative slave-making ants fit the predictions of Emery’s rule on the evolution of social parasites.