Proper timing of activities is one of the principal challenges faced by most organisms. Organisms need to account for various aspects in decision making like avoiding inordinate risks, synchronizing with resource availability, or finding mates. We provide analytical and simulation models to investigate the influence of life expectancy, resource competition and unpredictable environmental conditions (environmental uncertainty) on the evolutionarily stable distribution of emergence times in organisms depending on seasonally available resources. We focus on the partitioning of total phenotypic variance in emergence times into 1) genetic variance in mean emergence times between lineages and 2) environmental trait variance that determines the intra-lineage variance in the timing of emergence.Both, life expectancy of organisms and intensity of competition severely influence the evolutionary response to environmental uncertainty. Our main findings can be summarized as follows: 1) in general diversifying bet hedging (environmental trait variance) is the adequate mechanism to reduce the risk arising from environmental uncertainty while conservative bet hedging, i.e. delaying emergence into 'safe' phases of the season is restricted to short lived organisms and to situations with vanishing competition. 2) Environmental trait variance increases with increasing environmental uncertainty whereas 3) significant genetic variance evolves only under severe resource competition; it is driven by selection for an ideal free distribution of emergence times. 4) The level of genetic variance evolving declines with increasing life expectancy of organisms. 5) With sufficiently short life expectancy evolutionary branching and coexistence of distinctly different emergence strategies occurs; the number of co-occurring strategies is determined by the level of environmental uncertainty.Our model provides cues for understanding how different ecological factors contribute and interact to shape the evolution of emergence strategies.The proper timing of life-history events like pupation or emergence in insects, is an issue of far reaching fitness consequences (Bradshaw and Holzapfel 2007). Timing is important to meet periods of favorable abiotic and biotic environmental conditions and avoid unfavorable situations, e.g. by initiating a diapause (Schmidt et al. 2005). Emergence (or eclosion), for example, must be timed to avoid periods of adverse conditions like frost or drought. Ill-adapted timing may indeed limit a (geno)type's distribution (Chuine 2010). For example, in a controlled experiment mosquitoes of the species Wyeomyia smithii lost 74% (southern populations) and even 88% (northern population) of their fitness compared to the best-timed intermediate population (Bradshaw et al. 2004). Similar reasoning may apply to the proper timing of daily activities like foraging (Emerson et al. 2008, Miller-Rushing et al. 2010. Observed emergence patterns can be as complex as e.g. the trimodal strategy of the rose sawfly (Kawasaki et al. 2012).Timing i...
