Host-parasite coevolution can promote the evolution of seed banking as a bet-hedging strategy

Abstract

Seed (egg) banking is a common bet-hedging strategy maximizing the fitness of organisms facing environmental unpredictability by the delayed emergence of offspring. Yet, this condition often requires fast and drastic stochastic shifts between good and bad years. We hypothesize that the host seed banking strategy can evolve in response to coevolution with parasites because the coevolutionary cycles promote a gradually changing environment over longer times than seed persistence. We study the evolution of host germination fraction as a quantitative trait using both pairwise competition and multiple mutant competition methods, while the germination locus can be genetically linked or unlinked with the host locus under coevolution. In a gene-for-gene model of coevolution, hosts evolve a seed bank strategy under unstable coevolutionary cycles promoted by moderate to high costs of resistance or strong disease severity. Moreover, when assuming genetic linkage between coevolving and germination loci, the resistant genotype always evolves seed banking in contrast to susceptible hosts. Under a matching-allele interaction, both hosts' genotypes exhibit the same seed banking strategy irrespective of the genetic linkage between loci. We suggest host-parasite coevolution as an additional hypothesis for the evolution of seed banking as a temporal bet-hedging strategy.

Dormancy in Metacommunities

“…At the metacommunity scale, well-dispersed predators can eliminate spa- tial refuges for vulnerable prey, but predator-resistant dormant stages could introduce temporal refuges that stabilize prey populations in the metacommunity. In some systems, dormancy may even be an adaptation to host-parasite interactions (Verin and Tellier 2018), suggesting dormancy may be a trait of interest in evolving metacommunities that include predation. However, dormant propagules at a high risk of consumption (e.g., Waterkeyn et al 2011) could increase predatorabundances and destabilize prey populations(of several species) at the metacommunity scale via interpatch apparent competition.…”

Dormancy in metacommunities

“…For example, while high predator dispersal can eliminate spatial refuges for vulnerable prey, predator-resistant dormant stages could introduce temporal refuges that stabilize 382 prey populations in the metacommunity. In some systems, dormancy may even be an adaptation to host-parasite interactions (Verin and Tellier 2018), suggesting dormancy may be a trait of 384 interest in evolving metacommunities that include predation. However, dormant propagules at a high risk of consumption (e.g., Waterkeyn et al 2011) could increase predator abundances and 386 destabilize prey populations (of several species) at the metacommunity scale via inter-patch apparent competition.…”

Ecological, (epi)genetic and physiological aspects of bet-hedging in angiosperms

“…The evolution and diffusion of soil seed banking in different taxa and populations is not only linked to unpredictable climatic conditions but also to unstable co-evolutionary dynamics between host and parasites: seed banking is evolutionarily favoured when the cost of alleles for resistance to parasites and the disease severity are high (Verin and Tellier 2018). This is more likely to happen in more stable environments (e.g.…”

“…host-parasite cycles, predation) (see, e.g. Guzzon et al 2018;Long et al 2015;Verin & Tellier 2018;Volis and Bohrer 2013). On the contrary, bethedging has been subjected to negative selection during crop domestication in favour of rapid and uniform germination and field establishment even under sub-optimal conditions (Mitchell et al 2017).…”