Data from: Sexual selection affects the evolution of lifespan and ageing in the decorated cricket Gryllodes sigillatus

Recent work suggests that sexual selection can influence the evolution of ageing and lifespan by shaping the optimal timing and relative costliness of reproductive effort in the sexes. We use inbred lines of the decorated cricket, Gryllodes sigillatus, to estimate the genetic (co)variance between age-dependent reproductive effort, lifespan and ageing within and between the sexes. Sexual selection theory predicts that males should die sooner and age more rapidly than females. However, a reversal of this pattern may be favoured if reproductive effort increases with age in males but not in females. We found that male calling effort increased with age, whereas female fecundity decreased, and that males lived longer and aged more slowly than females. These divergent life-history strategies were underpinned by a positive genetic correlation between early-life reproductive effort and ageing rate in both sexes, although this relationship was stronger in females. Despite these sex differences in life-history schedules, age-dependent reproductive effort, lifespan and ageing exhibited strong positive intersexual genetic correlations. This should, in theory, constrain the independent evolution of these traits in the sexes and may promote intralocus sexual conflict. Our study highlights the importance of sexual selection to the evolution of sex differences in ageing and lifespan in G. sigillatus.

近期研究表明，性选择（sexual selection）可通过塑造两性繁殖投入的最优时机与相对成本，影响衰老与寿命的演化进程。本研究以装饰蟋蟀（Gryllodes sigillatus）的近交系为实验材料，估算了两性内部及两性之间，年龄依赖性繁殖投入、寿命与衰老之间的遗传（共）方差。性选择理论预测，雄性的寿命更短、衰老速率快于雌性。然而，若雄性的繁殖投入随年龄增长而提升，而雌性并非如此，则该两性差异模式可能发生逆转。本研究发现，雄性的求偶鸣唱投入随年龄增长而提升，而雌性的繁殖力（fecundity）则随年龄下降；同时雄性的寿命更长、衰老速率慢于雌性。上述分化的生活史策略，以两性早期繁殖投入与衰老速率间的正向遗传相关为支撑，不过该关联在雌性群体中更为显著。尽管两性在生活史时序上存在上述差异，但年龄依赖性繁殖投入、寿命与衰老均表现出显著的正向跨性别遗传相关。从理论层面而言，这将约束两性上述性状的独立演化进程，并可能推动基因座内性冲突（intralocus sexual conflict）的产生。本研究凸显了性选择对装饰蟋蟀（G. sigillatus）衰老与寿命的性别差异演化的重要作用。