Abstract
Evolutionary trade-offs are considered as one of the most critical factors in the evolution of life history traits, and play a key role in the evolution of organisms, as they limit the range of possible adaptive variations. One major challenge for evolutionary biologists is to detect and observe these trade-offs in natural environments, in order to understand and anticipate the evolution of life history traits. This chapter presents two approaches based on both mechanistic and statistical models used to represent the expected proximal mechanisms and the conditioning structure which links life history traits, revealing the presence of underlying trade-offs. It provides a simple theoretical example of a trade-off between two life history tactics (e.g. reproduction and migration) in relation to a survival event. One key question linked to life history strategies concerns the expression of potential trade-offs between growth and reproduction, reflecting the fact that an individual cannot invest in both traits simultaneously.