Aging dynamics in captive sea turtles reflect conserved life-history patterns across the testudine phylogeny

Abstract

Recent work has shown testudines can escape actuarial senescence for extended periods. However, understanding how the interplay between somatic aging and reproductive investment in highly fecund, long-lived ectotherms align with broader phylogenetic patterns remains a critical knowledge gap. Here, we present a comprehensive demographic analysis of age-specific changes in reproduction and mortality using a unique dataset on captive, known-aged green sea turtles Chelonia mydas. Despite substantial intraspecific variation, cumulative egg production showed no decline, increasing linearly for over two decades. However, mortality patterns followed the Gompertz Law, increasing exponentially with age. These results demonstrate a significant decoupling between sustained reproductive performance and age-specific mortality, building on a body of work that challenges the notion of uniformly arrested senescence. Nevertheless, life history strategies across testudines, including sea turtles, produce similar aging rates and remain low relative to endothermic tetrapods, reflecting conserved life-history patterns.