Evolution of serotiny in maritime pine (Pinus pinaster) in the light of increasing frequency of fires

Wildfire frequency and intensity in the Mediterranean region are predicted to increase with climate and anthropogenic changes in the following decades. Pines species often posses fire-embracing and fire-avoiding strategies that increase the probability of persistence and performance in fire-prone habitats. One such strategy is serotiny, i.e., the capacity to retain seeds in long-closed cones within the plant canopy; serotinous cones release seeds only when either a fire or a heat shock occurs. In this work, we used a simulation approach and Pinus pinaster populations as a model system to investigate how (i) an increased frequency of fire, (ii) genetic characteristics of serotiny, and (iii) observed differences in life histories interact to determine (a) risk of local population extinction and (b) temporal changes in the prevalence of serotiny in the modeled population. In addition, we tested whether the contemporary evolution of serotiny in the face of increased probability of occurrence of fires increased the probability of population persistence with respect to a scenario in which serotiny was not allowed to evolve. Our simulations showed that over the 300 years of simulated time, the evolution of serotiny did not substantially contribute to the persistence of populations. Extinction risk increased with the increasing probability of occurrence of fire and slightly decreased with (i) higher gene flow from outside the modeled population, and (ii) higher prevalence of serotiny at the beginning of the simulation. The prevalence of serotiny at the end of simulation time was difficult to predict and mostly driven by stochasticity. © 2014 Springer Science+Business Media Dordrecht.