Can prey exhibit threat-sensitive generalization of predator recognition? Extending the Predator Recognition Continuum Hypothesis

Abstract

Despite the importance of predator recognition in mediating predator-prey interactions, we know little about the specific characteristics that prey use to distinguish predators from non-predators. Recent experiments indicate that some prey who do not innately recognize specific predators as threats have the ability to display antipredator responses upon their first encounter with those predators if they are similar to predators that the prey has recently learned to recognize. The purpose of our present experiment is to test whether this generalization of predator recognition is dependent on the level of risk associated with the known predator. We conditioned fathead minnows to chemically recognize brown trout either as a high or low threat and then tested the minnows for their responses to brown trout, rainbow trout (closely related predator) or yellow perch (distantly related predator). When the brown trout represents a high-risk predator, minnows show an antipredator response to the odour of brown trout and rainbow trout but not to yellow perch. However, when the brown trout represents a low-risk predator, minnows display antipredator responses to brown trout, but not to the rainbow trout or yellow perch. We discuss these results in the context of the Predator Recognition Continuum Hypothesis.

Tadpoles of the bronze frog (Rana temporalis) assess predation risk before evoking antipredator defense behavior

“…their conspecifics falling prey). These findings support the threat sensitive hypothesis according to which prey species assess and adjust their behavior in accordance with the predation risk (Helfman 1989;Ferrari et al 2008). …”

Learning about Danger: Chemical Alarm Cues and Threat‐Sensitive Assessment of Predation Risk by Fishes

“…Ferrari et al (2008c) tested juvenile rainbow trout for additive responses to two different chemosensory cues. Trout exposed conspecific disturbance and chemical alarm cues combined responded in an additive fashion, supporting the sensory complement hypothesis.…”

“…Indeed, Ferrari et al (2008c) found that fathead minnows conditioned with a high concentration of alarm cue (high perceived risk) exhibited generalised learning of trout cues, while minnows conditioned with low concentrations of alarm cue (low perceived risk) did not. These results suggest that prey may generalise the recognition only to highly threatening species but not to those of lower perceived risks.…”

“…At the other extreme, recognition would be learned, but any acquired information could be fully generalised to appropriate stimuli. Ferrari et al (2007Ferrari et al ( , 2008c argue that such a continuum would arise primarily through variability in the spatial and/or temporal predictability of predation threats. This model consists of two related issues: (1) selection to learn and (2) selection to generalise.…”

“…However, under conditions where fewer heterospecifics represent actual predation threats (low predator to non-predator ratio), generalising to all heterospecifics might represent a reduction in time and energy available for other fitness-related activities. As such, depending on the predator and prey guild structure, the use of generalised or non-generalised predator recognition may allow prey to optimise threat-sensitive trade-offs (Ferrari et al 2007(Ferrari et al , 2008c.…”