Endopolyploidy and its role in shaping ant castes and colony dynamics: a study on Camponotus aff. balzani (Hymenoptera, Formicidae)

The high diversity in ants has been associated with some genomic divergences, including karyotype, nuclear genome size and DNA sequences. This study investigated if DNA ploidy levels varies among organs of the worker subcastes of the carpenter ant Camponotus aff. balzani. We also examined if DNA ploidy levels variation may contribute to variations in body size and functional specialization of the worker subcastes and its potential reproductive and behavioral differences among castes. Different DNA ploidy level were identified in the brain, post-pharyngeal gland, thoracic muscles, abdominal sternite muscles and midgut of the workers, resulting in similarities and divergences about the endopolyploid index (EI). The major workers presented the highest EI in the post-pharyngeal gland and thoracic muscles compared to median and minor workers, which may be associated with the different tasks that workers perform in the colony. The lowest EI was found in the brain of all workers subcastes. Moreover, gynes exhibited higher EI levels compared to males and worker subcastes. These findings suggest a complex interplay of genetics and caste determination in this ant. Overall, the results provide fundamental contributions for further studies to verify the role of endopolyploidy in the phenotypic plasticity among castes and subcastes of Camponotus aff. balzani, with potential implications for understanding similar processes in other social organisms.