The indispensable soma of Cardiocondyla obscurior ants

Abstract

The evolutionary mechanisms that shape aging in social insects are not well understood. It is commonly assumed that queens live long and prosperous, while workers are regarded as a short-lived disposable caste because of their low reproductive potential. Queens of the ant Cardiocondyla obscurior gain high fitness late in life by increasing investment into sexual offspring as they age. This results in strong selection against senescence until shortly before death. Here, we show that workers have the same lifespan and shape of aging as queens, even though workers lack reproductive organs and cannot gain direct fitness. Under consideration of the prevailing aging theories and the biology of the species, we hypothesize that programmed aging has possibly evolved under kin selection. Impact statementMorphologically distinct fertile queen and sterile worker castes in the model ant Cardiocondyla obscurior show the same pace and shape of aging, contradicting the paradigm of queen/worker lifespan divergence in social insects.