Genetic Isolation of Pogonomyrmex Harvester Ant Hybrid Lineages
Conference Year
January 2019
Abstract
Hybridization between species creates novel genetic combinations in their hybrids, which can become new species if they are reproductively isolated from their parents. Two species of harvester ant in the genus Pogonomyrmex have given rise to four pairs of hybrid lineages that differ dramatically from their parent species: although both P. barbatus and P. rugosus produce queen and worker offspring through nutritionally-driven environmental caste determination, hybrid populations produce them genetically, where the lineage of the male parent determines whether larvae develop into workers or immature queens (gynes). In this study, we tested whether the hybrid lineages are likely to represent new hybrid species by testing for genetic isolation at three sites where hybrids co-occur with one of their parent species. Workers from colonies within each of these sites were genotyped at 11 microsatellites known to vary significantly among both parental and hybrid lineage populations to determine the extent of gene flow. We used population assignment with the program Structure 2.1 to evaluate whether the two populations were genetically distinct, or showed signs of admixture. Based on results from previous studies at similar sites, we expect to observe little to no gene flow between any of the hybrid lineages and their parental Pogonomyrmex species. These results would represent one of the few cases described in animals of hybrid speciation.
Primary Faculty Mentor Name
Sara Helms Cahan
Status
Post-Bac Pre-Med
Student College
Larner College of Medicine
Program/Major
Biological Sciences, Integrated
Primary Research Category
Biological Sciences
Genetic Isolation of Pogonomyrmex Harvester Ant Hybrid Lineages
Hybridization between species creates novel genetic combinations in their hybrids, which can become new species if they are reproductively isolated from their parents. Two species of harvester ant in the genus Pogonomyrmex have given rise to four pairs of hybrid lineages that differ dramatically from their parent species: although both P. barbatus and P. rugosus produce queen and worker offspring through nutritionally-driven environmental caste determination, hybrid populations produce them genetically, where the lineage of the male parent determines whether larvae develop into workers or immature queens (gynes). In this study, we tested whether the hybrid lineages are likely to represent new hybrid species by testing for genetic isolation at three sites where hybrids co-occur with one of their parent species. Workers from colonies within each of these sites were genotyped at 11 microsatellites known to vary significantly among both parental and hybrid lineage populations to determine the extent of gene flow. We used population assignment with the program Structure 2.1 to evaluate whether the two populations were genetically distinct, or showed signs of admixture. Based on results from previous studies at similar sites, we expect to observe little to no gene flow between any of the hybrid lineages and their parental Pogonomyrmex species. These results would represent one of the few cases described in animals of hybrid speciation.