Early-life stress weakens actuarial senescence in bryozoans

In the colonial marine bryozoan Bugula neritina, researchers manipulated early-life stress by experimentally extending the larval period, imposing an energetic challenge. They then monitored the survival, fecundity, and growth of more than 500 individuals in the field across their lifetimes to evaluate trajectories of actuarial and reproductive senescence. Although colonial organisms with indeterminate growth have been theorized to display negligible senescence, the oldest individuals showed strong declines in both survival and reproductive output regardless of larval stress. Adults that developed from stressed larvae exhibited lower overall fitness in terms of lifetime reproductive success. However, these individuals experienced weaker actuarial senescence, alongside nuanced evidence suggesting that early-life stress may also decrease rates of reproductive senescence.