Publication details
Influence of food availability and predation risk on growth and maturation of Cloeon dipterum (Ephemeroptera: Baetidae)
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| Year of publication | 2015 |
| Type | Appeared in Conference without Proceedings |
| Citation | |
| Description | Most fitness-related traits in aquatic insects (such as larval growth, survival, size and age at maturation and fecundity) are phenotypically plastic and change in response to the amount and quality of resources or under predation risk. While better food conditions typically lead to faster growth and earlier maturation at larger body size and hence higher fecundity, theory predicts that the effects of predation risk can be more varied and will depend on its strength and selectivity with respect to size or stage. Previous studies on rheophilic mayflies reported (i) faster growth and earlier maturation at smaller size or (ii) slower growth and later maturation at the same size under predation risk. Both patterns are consistent with mortality that is constant or increases with both size and activity of the larvae. However, comparable results for standing-water species are lacking. To fill this gap, we carried out a full-actorial lab experiment to study the influence of food availability (full/reduced) and predation risk (present/absent predator cues) on individual growth of larvae of the mayfly Cloeon dipterum, a common and widespread species in standing waters. Early-instar Cloeon obtained from a small pond on September 16, 2014 were randomly assigned the four treatments (n=30–35 each) and reared individually until death or emergence in ~170 ml of water in plastic cups at 18 °C. Larvae were fed with Stigeoclonium green algae daily (full) or 3 days per week (reduced). We used individually kept Aeshna larvae (Odonata) that often co-occur with Cloeon to generate predator cues by adding water mixed from all Aeshna tanks to each aquarium with mayflies every second day. Our results indicate interacting, sex-specific effects of resources and predation risk on growth and body size of mayflies. Both male and female larvae developed faster in full food. Final-instar male larvae were significantly larger in full food independent of predator cues, while final-instar female larvae were larger in full food only in the absence of predator cues. In addition, males developed significantly longer in the presence of predation cues. These results suggest that male and female Cloeon might experience different selection pressures on adult size. |