Impact of parasite sympatry on the geographic mosaic of coevolution

• Published in: Ecology (Durham) 2006-02, Vol.87 (2), p.382-394
• Main Authors: Johnson, Christine A., Herbers, Joan M.
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal behavior; Animal, plant and microbial ecology; Animals; Ants; Ants - genetics; Ants - physiology; Biological and medical sciences; Biological Evolution; Brood parasitism; Coevolution; Colonies; competition; Ecological genetics; Ecology; Formicidae; Fundamental and applied biological sciences. Psychology; General aspects; geographic mosaic of coevolution; Geography; Host-Parasite Interactions; host-parasite relationships; Insect colonies; Insect ecology; interference effects; intraguild interactions; intraspecific competition; Parasite hosts; Parasites; parasitoids; Protomognathus americanus; Reproducibility of Results; slave-making ants; Social parasitism; Species Specificity; Temnothorax curvispinosus; Temnothorax duloticus; Temnothorax minutissimus; Temonthorax curvispinosus
• ISSN: 0012-9658; 1939-9170
• DOI: 10.1890/05-1093

Slave-making ants are specialized social parasites that steal the young from colonies of their host species to augment their slave supply. The degree of parasite-host specialization has been shown to shape the trajectory along which parasites and hosts coevolve and is a prime contributor to the geographic mosaic of coevolution. However, virtually nothing is known about extrinsic influences on parasite-host dynamics, although the simple addition of a competing slave-maker may significantly alter selection pressures. Here we report the effect of two sympatric slave-makers on a single host. We measured temporal and spatial changes in colonies of the primary host Temnothorax curvispinosus that had been placed in field enclosures along with a single colony of either one or both species of the North American slave-making ants Protomognathus americanus and Temnothorax duloticus. Each slave-maker species alone had a negative impact on its hosts, although one slave-maker species more frequently decimated its host assemblage and then went extinct. Nevertheless, the combined effect in mixed-parasite enclosures was, surprisingly, greatly attenuated. Virulent slave-maker growth and prudent slave-maker decay in these shared enclosures, together with field data showing an inverse proportional relationship between the two slave-makers in natural populations, suggest that their checkered distribution is a consequence of direct asymmetrical antagonism between parasites. Thus, our results imply a tripartite coevolutionary arms race, whereby intraguild interactions among social parasites strongly affect the realized selection pressures on hosts and contribute to the geographic mosaic of coevolution.