The Rate of Degradation of Chemical Cues Indicating Predation Risk: An Experiment and Review

Abstract

Many prey taxa use kairomones or alarm pheromones to assess the risk of predation in aquatic environments, and the rate at which these cues attenuate determines how precisely they indicate the local density of predators. We estimated the rate of degradation of chemical cues generated by Aeshna dragonfly larvae feeding on Rana temporaria tadpoles. The half-life of the cue was 35 h and was not influenced by whether it was aged in pond water or tap water or whether other tadpoles were present in the container in which cue-aging occurred. A review of other published estimates of predator cue half-life revealed values of 0.2-126 h, and variation among studies was unrelated to the type of aging water, the venue in which water was aged or prey behavior observed (laboratory, field), or the type of behavior that was recorded. We conclude that factors affecting the persistence of predator cues remain uncertain in spite of their importance for understanding the evolution of induced defenses. AbstractMany prey taxa use kairomones or alarm pheromones to assess the risk of predation in aquatic environments, and the rate at which these cues attenuate determines how precisely they indicate the local density of predators. We estimated the rate of degradation of chemical cues generated by Aeshna dragonfly larvae feeding on Rana temporaria tadpoles. The halflife of the cue was 35 h and was not influenced by whether it was aged in pond water or tap water or whether other tadpoles were present in the container in which cue-aging occurred. A review of other published estimates of predator cue half-life revealed values of 0.2-126 h, and variation among studies was unrelated to the type of aging water, the venue in which water was aged or prey behavior observed (laboratory, field), or the type of behavior that was recorded. We conclude that factors affecting the persistence of predator cues remain uncertain in spite of their importance for understanding the evolution of induced defenses.

The relative importance of prey-borne and predator-borne chemical cues for inducible antipredator responses in tadpoles

“…In a preliminary study, we confirmed that A. cyanea larvae do not defecate after being deprived of food for 3 days. It has been claimed that not only defecation may generate digestionreleased prey-borne cues (Brown et al 1995), but cues that label the predators as dangerous are known to degrade within 48 h or less (Peacor 2006;Ferrari et al 2008;Van Buskirk et al 2014).…”

“…Even if the duration of food restriction is known, it is not always clear that prey-borne cues are completely absent. The rate of degradation of pre-consumption prey-borne cues has been measured (Peacor 2006;Ferrari et al 2008;Van Buskirk et al 2014), but predators may defecate long after they consumed prey and digestion-released prey-borne cues may therefore persist. Observed prey responses may therefore not be attributed solely to continually released predator-borne cues (but see Petranka and Hayes 1998;Schoeppner and Relyea 2009).…”

In Space and Time: Territorial Animals are Attracted to Conspecific Chemical Cues

“…Olfactory signals differ from other forms of communication because they can continue to broadcast information for hours in the absence of the signaler, and can thus have a lasting impact on space use (Chivers et al 2013; Van Buskirk et al 2014; Campbell & Roberts 2015). Like other signal types, chemical cues attract (Durisko & Dukas 2013; Bett & Hinch 2015), repel (Goodale & Nieh 2012; Ibáñez et al 2012), and immobilize conspecifics (Brechbühl et al 2008; Fraker et al 2009).…”

Spatially heterogeneous selection in nature favors phenotypic plasticity in anuran larvae

“…One example is habitat/host race formation, in which populations evolve ecological specialization in response to variation in habitat or host species (Kawecki 1997;Nosil et al 2005;Van Buskirk 2014). One example is habitat/host race formation, in which populations evolve ecological specialization in response to variation in habitat or host species (Kawecki 1997;Nosil et al 2005;Van Buskirk 2014).…”

“…However, the spatial structure of risk depends on details of prey risk assessment and predator behavior. Predator chemicals persist 8-40 h in lentic habitats (Van Buskirk et al 2014) and diffuse as much as 0.5-2 m (Turner and Montgomery 2003;Wisenden 2008;Takahara et al 2012). This is true when (1/n) > Vt2d, where n is the density of the predator, V is the velocity of the predator, t is the half-life of the signal indicating risk, and d is the distance over which the signal is detectable.…”