The biased evolution of generation time

Many life-history traits are important determinants of the generation time. For instance, semelparous species whose adults reproduce only once have shorter generation times than iteroparous species that reproduce on several occasions – assuming equal development duration. A shorter generation time ensures a higher growth rate in stable environments where resources are in excess, and is therefore a positively selected feature in this situation. In a stable and limiting environment, all combinations of traits that produce the same number of viable offspring are selectively equivalent. Here we study the neutral evolution of life-history strategies with different generation times, and show that the slowest strategy represents the most likely evolutionary out- come when mutation is considered. Indeed, strategies with longer generation times generate fewer mutants per time unit, which makes them less likely to be replaced within a given time period. This ‘turnover bias’ favors the evolution o...