  D. discoideum has been recently suggested as an example of bet-hedging. Upon
starvation a population of unicellular amoebae splits between aggregators,
which form a fruiting body made of a stalk and resistant spores, and
non-aggregators. Spores are favored by long starvation periods, but vegetative
cells can exploit resources in fast-recovering environments. This partition can
be understood as a bet-hedging strategy that evolves in response to stochastic
starvation times. A genotype is defined by a different balance between each
type of cells. In this framework, if the ecological conditions are defined in
terms of the mean starvation time (i.e. time between onset of starvation and
the arrival of a new food pulse), a single genotype dominates each environment,
which is inconsistent with the huge genetic diversity observed in nature. We
investigate whether seasonality, represented by a periodic alternation in the
mean starvation times, allows the coexistence of several strategies. We use a
non-spatial (well-mixed) setting where different strains compete for a pulse of
resources. We find that seasonality, which we model via two seasons, induces a
temporal storage effect that can promote the stable coexistence of multiple
genotypes. Two conditions need to be met. First, the distributions of
starvation times in each season cannot overlap in order to create two well
differentiated habitats within the year. Second, numerous growth-starvation
cycles have to occur during each season to allow well-adapted strains to grow
and survive the subsequent unfavorable period. Additional tradeoffs among
life-history traits can expand the range of coexistence and increase the number
of coexisting strategies, contributing towards explaining the genetic diversity
observed in D. discoideum
