Influence of experimental venue on phenotype: multiple traits reveal multiple answers


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1. Experiments in ecology occur in the laboratory, mesocosm or field. The choice of venue can influence the outcome and may be associated with trade-offs involving realism and precision.

2. We evaluated these trade-offs in an experiment measuring effects of venue on larval traits of Rana temporaria tadpoles. The design included laboratory, mesocosm and field venues, crossed with two treatments (presence and absence of caged Anax imperator dragonfly larvae). Realism of venues was evaluated by comparing experimental with wild tadpoles.

3. Venue influenced nearly every trait we measured, but some were more sensitive to venue than others. Larval and metamorphic performance, external morphology and predator-induced plasticity in many traits varied among venues, while behaviour was less dependent on venue. Tadpoles in mesocosms were most similar to those in field enclosures and the wild, although the phenotypic response to predation risk was greatest in the mesocosm venue. The laboratory environment triggered highly distinctive morphology. Precision was not higher in the laboratory than in other venues.

4. This study suggests that both constraints and research questions must be considered when choosing an appropriate experimental venue.