Fisher & Salguero-Gomez reproductive death final with tables
Diana O. Fisher, Roberto Salguero‐Gómez · 2022
Organisms that breed only once are semelparous.Theoretical frameworks to explain the evolution of semelparity are based on the premise of reproductive costs to future survival, and emphasize either a high risk of death after breeding for environmental reasons (the demographic model) or disproportionate fitness benefits at higher reproductive effort (the reproductive effort model).Here, we review environmental drivers that increase risk of postreproductive death, conditions in which lethal reproductive efforts are beneficial, biological mechanisms of death in semelparous organisms, and of reproductive capacity loss in obligate semelparous females and males.We find that age-specific mortality risk is overwhelmingly the dominant driver of facultative and obligate semelparity in animals and plants: most species follow predictions of the demographic model.We find that female semelparous organisms die from diverse mechanisms that cause somatic damage as they increase reproductive output.Semelparous female animals are nearly all predators, suggesting a nutritional constraint on fecundity associated with the viability of the semelparous life history strategy.We propose that in species in which only males are semelparous, the driver is always post-mating male sexual competition.Sexual conflict occurs because females escalate sperm competition to gain fitness benefits, and males can increase reproductive success through a mechanism of competition that causes lethal somatic damage, typically involving extreme investment in mate-guarding.In organisms with obligate male-only semelparity the mechanism of death is often decoupled from the mechanism of reproductive capacity loss, which typically occurs at sexual maturity.We propose that this pre-breeding loss of future reproductive capacity is associated with a post-mating sexual competition strategy analagous to 'capital breeding', in which males keep a lifetime store of gametes near the outside of the body to transfer quickly in a single mating period.We suggest that male-only semelparity is