Population structure of Sericomyrmex amabilis, fungus-growing host of a rare parasite
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Date
2024-05
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The Ohio State University
Abstract
Symbiotic interactions are ubiquitous, found in all habitat types from oceans to tropical rainforests. These coevolving organisms or symbiotic species networks are not only central components of biodiversity but enable community resilience to environmental change. Different communities vary in species makeup and environmental factors. Thus, coevolution among symbiotic species inherently is tied to biotic and abiotic factors resulting in a geographic mosaic of differing selective environments. The mercenary ant symbiotic species network includes the fungus-growing ant, Sericomyrmex amabilis host, and two antagonistic parasitic species. The first is an obligate long-term guest ant social parasite, Megalomyrmex symmetochus, and the second is the raider ant, Gnamptogenys hartmani. The guest ant is a protective symbiont that shields the farmer ants from destructive Gnamptogenys raids, acting like the farmer ant’s mercenary soldiers. These species are found in Central and South America, but exact ranges and populations are unclear. Determining the population structure of the host species is the first step toward understanding the coevolutionary dynamics among these species. To investigate the population genetics of the farmer ant hosts found in Panama and Costa Rica, we used eight microsatellite markers (genetic loci) to answer the following questions: 1) Is there significant genetic differences among S. amabilis sub-populations in Panama? and 2) Is there detectable isolation-by-distance when comparing samples from sites along the Panama Canal (PLR, BCI, Plantation Road, Fort Sherman), El Llano, Panama, and La Selva, Costa Rica? We analyzed 79 samples and found that the Costa Rica S. amabilis subgroup is a genetically distinct population compared to Panamanian populations. Further, gene flow between Barro Colorado Island and the mainland appears to be slightly restricted, which eventually could form an even more distinct inbred island population in Panama.
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Keywords
population genetics, fungus-growing ants, microsatellites, symbiosis biology, coevolution