Resource allocation as a driver of senescence: Life history tradeoffs produce age patterns of mortality

We present a theoretical model of behavior and nutrient allocation for organisms with discrete juvenile (larval) and adult stages, each with distinct diets, nutritional needs and foraging strategies. We predict optimal schedules of foraging and reproduction across a limited lifespan and examine the consequences for nutrient dynamics, paying particular attention to conditions under which it is optimal to tolerate starvation or to conserve resources and how these decisions affect mortality across the life cycle. We derive these optimal behavioral schedules assuming two alternative scenarios of environmental conditions, in which we do or do not impose deterioration in survival with age (senescence). We find that even in the absence of imposed senescence, terminal investment near the end of reproductive lifespans reduced survival probabilities of older individuals. We predicted earlier terminal investment and earlier senescence when reproductive overheads are low and when the survival costs of carbon depletion are small. Our findings suggest that resource allocation decisions alone are sufficient to produce signals of senescence and other age-patterns of mortality in animals optimizing decision schedules across their reproductive life cycles. We conclude that behavioral patterns of individuals can be strong drivers of observed d