On the joint evolution of dispersal and dormancy in metapopulations

Dormancy and dispersal are alternative adaptations for living in chronically variable environments. Wt:analyze simple multip-patch models assuming density-independent fitnesses to explore their Joint effects on long-term fitness. We: first consider dispersal and dormancy in a two-patch metapopulation where fitnesses vary cyclically within patches but out of phase between patches. In this model either individuals that all migrate between patches every year or individuals that display some propensity for dormancy are favored, but not a combined dispersal/dormancy strategy. Also, dispersal is favored over dormancy until the fitness cost of dispersal greatly exceeds the cost of dormancy. In contrast, in a metapopulation where within-patch fitnesses vary randomly instead of cyclically, natural selection should often favor genotypes that express some propensity for both dispersal and dormancy, especially when the cost of dispersal is relatively high, the frequency of catastrophic fitness failures within a patch are high, and the metapopulation is comprised of few patches. As the number of patches in the metapopulation increases, higher dispersal propensity and lower dormancy propensity is favored, even when the cost associated with dispersal is relatively high. The apparent superiority of dispersal as a bet-hedging strategy under many conditions is considered in light of these results and the relative effects of dispersal and dormancy on geometric mean fitness.