Saumon a la Kaitala et Getz, sauce hollandaise

We investigate the interplay of population dynamics and adaptive dynamics via the timing of reproduction, in the context of a caricatural discrete-time model. We find that semelparity can cause co-existence of different population-dynamical attractors and that resonance of life-span relative to population-dynamical fluctuations can have a profound effect on invasibility and the resulting evolutionarily stable life-history. Different local attractors of the resident population dynamics can have different invasion properties. Successful invasion in one attractor can be followed by extinction of the former invader, ultimately leading the resident to the same attractor, but phase-shifted, or to another attractor. So a strategy can be `invasible, yet invincible'. In addition, our analysis emphasizes that, for a fluctuating population, one must carefully distinguish between polymorphisms and mixed strategies.