Impact of temperature and photoperiod on survival and biomarkers of senescence in common woodlouse

Most living organisms display a decline in physiological performances when ageing, a process called senescence that is most often associated with increased mortality risk. Previous researches have shown that both the timing and the intensity of senescence vary a lot within and among species, but the role of environmental factors in this variation is still poorly understood. To fill this knowledge gap, we investigated the impact of environmental conditions on the strength of senescence using an experimental design applied to a population of common woodlouse Armadillidium vulgare intensively monitored in the lab. Cellular senescence biomarkers are available in woodlouse and are age-related. These biomarkers provide relevant biomarkers to test the impact of environmental conditions, through changes in temperature and photoperiod, on individuals of the same age maintained in different environmental conditions. We found different effects of the environmental changing: the increasing of day light modification leaded the same effect as age on our senescence biomarkers while temperature modifications leaded the opposite effect as age on the β-galactosidase activity and cell size. We also demonstrated the existence of sex-specific responses to changes in environmental conditions. By using an experimental approach and biomarkers of senescence in woodlouse, we show that environmental conditions and sex both shape the diversity observed in senescence patterns of woodlouse and underline the importance of identifying senescence biomarkers to understand how environmental conditions influence the evolution of senescence.