Dispersal and dormancy strategies among insect species competing for a pulsed resource

Abstract

Dormancy and dispersal are thought to be major adaptive mechanisms that enable short‐lived organisms to cope with environmental stochasticity. The few empirical investigations that have explored the relationship between these two strategies in disturbed environments have focused mainly on communities of annual desert plants and suggest that dispersal plays a negligible role, as compared with dormancy, in reducing the risk of genotype extinction. We predict that the relative advantage of dormancy versus dispersal is likely to be more balanced in species that disperse actively to select their reproductive locality. To examine this prediction, we explored the dormancy and dispersal capacities of four actively dispersing sibling weevil species (Curculio spp.) that exploit the same, highly variable resource (oak acorns). The ability of each species to spread risks over time was estimated from the variability of dormancy duration within cohorts, while their ability to disperse spatially was quantified by flight performance. We show that a first species, C. elephas, which was able to spread risk over time through dormancy, exhibited only medium flight capacities. In contrast, a second species, C. glandium, was able to fly over very long distances, but was hardly capable of spreading risk over time. Surprisingly, the two remaining species (C. venosus and C. pellitus) proved inefficient in spreading risk either in space or in time and seem to exhibit risk avoidance rather than risk‐spreading strategy. We conclude that this strong diversification of dispersal–dormancy strategies observed among these four sibling species might contribute to stabilising their coexistence.

Zero‐sum landscape effects on acorn predation associated with shifts in granivore insect community in new holm oak (Quercus ilex) forests

“…Curculio species have moderate flight abilities and great diapause variability (with adults of the same cohort emerging over several years) (Pélisson et al, 2013), while Cydia exhibits good dispersal abilities but does not have any dormancy strategy (Schumacher et al, 1997). Curculio species have moderate flight abilities and great diapause variability (with adults of the same cohort emerging over several years) (Pélisson et al, 2013), while Cydia exhibits good dispersal abilities but does not have any dormancy strategy (Schumacher et al, 1997).…”

“…). showing that C. glandium is able to disperse double the maximum distance estimated for C. elephas (1200 m vs. 600 m, respectively)(Pélisson et al, 2013). By contrast, C. glandium, which emerges in spring(Venner et al, 2011) and has a greater dispersal capacity, showed an evenly distributed infestation probability among forest types, just as Cydia did.…”

“…In this study, we have analysed the effects of age and connectivity of forest patches in the composition of the granivore guild of insects and the consequences (negative, positive, neutral) for acorn predation in expanding holm oak (Quercus ilex L.) forests in NE Spain. These include weevils (Curculio glandium Marsham and C. elephas Gyllenhal (Curculionidae)) and moths (Cydia fagiglandana Zeller (Tortricidae)) (Espelta, Cortés, Molowny-Horas, & Retana, 2009;Jimenez-Pino, 2011), which differ in their dispersal ability (higher in C. fagiglandana, intermediate in C. glandium and lower in C. elephas) and resilience to unsuitable conditions (Jimenez-Pino, 2011;Pélisson, Bernstein, François, Menu, & Venner, 2013;Schumacher, Weyeneth, Weber, & Dorn, 1997;Soria, 1999). These new Mediterranean forests offer an ideal study system to assess these questions as Q. ilex can be considered a foundation species with large implications in ecosystem functioning (sensu Angelini, Altieri, Silliman, & Bertness, 2011) and its acorns are heavily depredated by a guild of predators.…”

Beyond predator satiation: Masting but also the effects of rainfall stochasticity on weevils drive acorn predation

“…, Pélisson et al. ). In fact for C. elephas , genetic differences and restricted gene flow among populations are observed beyond 300 m (H. Ruiz‐Carbayo, unpublished manuscript ).…”

“…Both C. glandium and C. elephas overwinter underground, but the two species present different phenologies: C. glandium emerges earlier, mostly in spring (Pélisson et al. ), while the emergence of C. elephas is restricted to autumn (Espelta et al. , Bonal et al.…”