Effects of behavioral and morphological plasticity on risk of predation in a Neotropical tadpole

Abstract

Predator-induced phenotypic plasticity is widespread among aquatic animals, however the relative contributions of behavioral and morphological shifts to reducing risk of predation remain uncertain. We tested the phenotypic plasticity of a Neotropical tadpole ( Rana palmipes) in response to chemical cues from predatory Belostoma water bugs, and how phenotype affects risk of predation. Behavior, morphology, and pigmentation all were plastic, resulting in a predator-induced phenotype with lower activity, deeper tail fin and muscle, and darker pigmentation. Tadpoles in the predator cue treatment also grew more rapidly, possibly as a result of the nutrient subsidy from feeding the caged predator. For comparison to phenotypes induced in the experiment, we quantified the phenotype of tadpoles from a natural pool. Wild-caught tadpoles did not match either experimentally induced phenotype; their morphology was more similar to that produced in the control treatment, but their low swimming activity was similar to that induced by predator cues. Exposure of tadpoles from both experimental treatments and the natural pool to a free-ranging predator confirmed that predator-induced phenotypic plasticity reduces risk of predation. Risk of predation was comparable among wild-caught and predator-induced tadpoles, indicating that behavioral shifts can substantially alleviate risk in tadpoles that lack the typical suite of predator-induced morphological traits. The morphology observed in wild-caught tadpoles is associated with rapid growth and high competition in other tadpole species, suggesting that tadpoles may profitably combine a morphology suited to competition for food with behaviors that minimize risk of predation.

Rapid turnover of tissue nitrogen of primary consumers in tropical freshwaters

“…However, the low explanatory power of the three-parameter model (r 2 =0.24; Table 3) and large standard error of the turnover estimate prevent any strong conclusions (Table 2). We have previously observed variable growth rates in tadpoles of this species even within a single experimental pool (McIntyre et al 2004), and such differences probably contributed to inconsistent 15 N enrichment.…”

“…2). Tadpole growth rates in field enclosures and experimental pools at our study site average 0.6-1.4% per day (McIntyre et al 2004;Solomon et al 2004), potentially accounting for all of the N turnover observed in this study. Though no data are available for the snail species, our observations under experimental and field conditions suggest that their growth rates are much lower than the observed turnover rates of muscle N (see also Kemp et al 1990).…”

Natural variation in morphology of larval amphibians: Phenotypic plasticity in nature?

“…Amphibian larvae are partially protected from predation by a suite of traits that includes a deep tail fin and tail muscle (McCollum and Van Buskirk 1996, Van Buskirk and McCollum 2000a, Van Buskirk and Schmidt 2000, McIntyre et al 2004, Teplitsky et al 2005). The functional consequences of variation in tail shape are not fully understood.…”

Morphologische Parameter als Biomarker in der Ökotoxikologie – natürliche und schadstoffinduzierte Variabilität

“…Beispiele für umweltinduzierte morphologische Plastizität sind z. B. durch Prädatoren ausgelöste Veränderungen von Körperformen bei Beutespezies (McIntyre et al 2004), durch physisches Training ausgelöste Veränderungen der Muskelstruktur (Johnston 2006), oder durch Temperaturund Nahrungsschwankungen induzierte morphologische Veränderungen in zentralen Stoffwechselorganen wie der Leber bei Wirbeltieren oder der Mitteldarmdrüse bei Wirbellosen (Braunbeck et al 1987;Segner und Möller 1984;Vogt et al 1986;Dittbrenner et al 2008). Entsprechend führt auch die Belastung mit toxischen Stoffen zu morphologischen Veränderungen in Zielorganen und -zellen (Au 2004;Braunbeck et al 1989;Braunbeck 1998;Burkhardt-Holm et al 1998;Gernhöfer et al 2001;Hinton et al 1978Hinton et al , 2008Köhler et al 1992;Triebskorn und Künast 1990;Vogt 1987).…”