Artificial selection for adult predation survival impacts life history and morphology in guppies (Poecilia reticulata)

Predation is accepted as a major evolutionary driver of life history and morphology. However, whether these traits evolve directly via predation or via indirect effects is largely unresolved. We used artificial selection over three generations to experimentally test the impact of adult predation on the evolution of life history and morphology in guppies (Poecilia reticulata). We found that, compared to control fish, predation-selected fish produced larger offspring and larger broods early in life. However, other life history parameters, such as interbrood interval and total number of offspring, showed no response. We also found that predation-selected for smaller and lighter females and for shorter tails and gonopodia in males, with no effect on body colouration. Our results show that while several traits evolve fast under selection on adult predation, several classic predation-dependent traits seem unaffected by predation selection. By comparing our experimental results to those from natural populations we can disentangle the contribution of direct and indirect effects on trait evolution under predation pressure.