You can’t run but you can hide: refuge use in frog tadpoles elicits density-dependent predation by dragonfly larvae

Abstract

The potential role of prey refuges in stabilizing predator-prey interactions is of longstanding interest to ecologists, but mechanisms underlying a sigmoidal predator functional response remain to be fully elucidated. Authors have disagreed on whether the stabilizing effect of prey refuges is driven by prey- versus predator-centric mechanisms, but to date few studies have married predator and prey behavioural observations to distinguish between these possibilities. We used a dragonfly nymph-tadpole system to study the effect of a structural refuge (leaf litter) on the predator's functional response, and paired this with behavioural observations of both predator and prey. Our study confirmed that hyperbolic (type II) functional responses were characteristic of foraging predators when structural cover was low or absent, whereas the functional response was sigmoidal (type III) when prey were provided with sufficient refuge. Prey activity and refuge use were density independent across cover treatments, thereby eliminating a prey-centric mechanism as being the genesis for density-dependent predation. In contrast, the predator's pursuit length, capture success, and handling time were altered by the amount of structure implying that observed shifts in density-dependent predation likely were related to predator hunting efficiency. Our study advances current theory by revealing that despite fixed-proportion refuge use by prey, presence of a prey refuge can induce density-dependent predation through its effect on predator hunting strategy. Ultimately, responses of predator foraging decisions in response to changes in prey availability and search efficiency may be more important in producing density-dependent predation than the form of prey refuge use.

Investment into Defensive Traits by Anuran Prey (Lithobates pipiens) Is Mediated by the Starvation-Predation Risk Trade-Off

“…Severely food-restricted tadpoles will show no response to risk, moderately food-restricted tadpoles will express either a morphological or behavioural response to high risk, and food-saturated tadpoles will exhibit responses to predation risk in all traits. Northern leopard frog ( Lithobates pipiens ) tadpoles typically respond to predation risk by decreasing activity [27], [28], [29], [30] and increasing relative tail fin and/or tail muscle depth [28], [29]. While plasticity in life history traits in response to predation risk varies both within and between species [27], [31], [32], we predicted that with no food limitation tadpoles would increase both body size [29] and development speed when under predation risk.…”

Shelter availability, stress level, and digestive performances in the aspic viper

“…The benefits of retreat site selection have been examined in species belonging to various lineages [e.g. arachnids, fish, reptiles, mammals and amphibians (Bulova, 2002;Kearney, 2002;Goldsbrough et al, 2004;Kotler et al, 2004;Millidine et al, 2006;Hossie and Murray, 2010;Hossie and Murray, 2011)]. However, previous investigations focused on constraining temperature conditions, i.e.…”

Spatial arrangement of prey affects the shape of ratio-dependent functional response in strongly antagonistic predators

“…Detecting sigmoidal functional responses (prey or predator dependent) in natural systems is inherently challenging (Marshal andBoutin 1999), andVucetich et al (2002) acknowledge this difficulty as well for ratio-dependent models. In contrast, experimental work is clearly well positioned to reveal conditions where sigmoidal models better represent ecological processes (Hassell 1978, Kratina et al 2007, Hossie and Murray 2010, and therefore remains critical in the development and testing of ecological theory.…”