Stabilisation of Fluctuating Population Dynamics via the Evolution of Dormancy

Dormancy is usually understood as a strategy for coping with extrinsic environmental variation, but intrinsic population fluctuations also create conditions where dormancy is adaptive. By analysing simple population models, we show that population fluctuations favour the evolution of dormancy, but dormancy stabilises population dynamics. This sets up a feedback loop that can enable the coexistence of alternative dormancy strategies. Over longer timescales, we show that the evolution of dormancy to an evolutionary stable state can drive populations to the edge of stability, where dynamics are only weakly stabilised. We briefly consider how these conclusions are likely to apply in more complex community contexts. Our results suggest that chaos and high-amplitude population cycles are highly vulnerable to invasion and subsequent stabilisation by dormancy, potentially explaining their rarity. At the same time, the propensity of ecological dynamics to fluctuate may be an underappreciated driver of the evolution of dormancy.