This study investigates the impact of predation on the life history evolution of Trinidadian guppies (*Poecilia reticulata*). The researchers examined three types of predation treatments: high predation intensity on adults (*Crenicichla*), moderate predation intensity on juveniles (*Rivulus*), and low predation intensity on all size classes (*Aequidens*). They found that guppies from *Crenicichla* localities exhibit significantly larger reproductive allotment and shorter interbrood intervals, produce more and smaller offspring, and mature at a smaller size compared to guppies from *Rivulus* and *Aequidens* localities. These differences are consistent with theoretical predictions, suggesting that predation selects for these life history traits. The study also discusses three hypotheses to explain these patterns: environmental influence, differences in predation intensity, and predator-mediated differences in intraspecific competition. The findings highlight the rapid evolution of life history traits in response to predation pressure.This study investigates the impact of predation on the life history evolution of Trinidadian guppies (*Poecilia reticulata*). The researchers examined three types of predation treatments: high predation intensity on adults (*Crenicichla*), moderate predation intensity on juveniles (*Rivulus*), and low predation intensity on all size classes (*Aequidens*). They found that guppies from *Crenicichla* localities exhibit significantly larger reproductive allotment and shorter interbrood intervals, produce more and smaller offspring, and mature at a smaller size compared to guppies from *Rivulus* and *Aequidens* localities. These differences are consistent with theoretical predictions, suggesting that predation selects for these life history traits. The study also discusses three hypotheses to explain these patterns: environmental influence, differences in predation intensity, and predator-mediated differences in intraspecific competition. The findings highlight the rapid evolution of life history traits in response to predation pressure.