The ability of prey to survive predator encounters is one of the strongest selective force affecting the spatial and temporal distributions of animals, and shaping their behaviour, morphology and life history traits. However, predation risk is rarely predictable in space and time. Predators come and go, and the probability of encountering predators may vary from one moment to the next, on a daily, lunar, seasonal or yearly cycle. As a result, predation is often associated with a considerable variation and uncertainty.  How prey perceive predation threats under conditions of spatial and temporal variability is poorly understood.  Moreover, the question of how variability and uncertainty of risk influences the interaction of different forms of chemosensory cues is likewise poorly understood.  

My  research program is currently examining three general themes along the common question of ‘how do prey respond to uncertainty in risk’?  The common approach within this proposal is to rely heavily on field studies.  A common (and persistent) fault with modern chemical ecology is the heavy reliance on laboratory studies.  To address this, we conduct field experiments under fully natural conditions.  Field trials will focus on the use of several well studied model species: 1) Atlantic salmon (Catamaran Brook, NB), 2) guppies (Northern Range Mountains, Trinidad and Tobago) and 3) Hart’s rivulus (Northern Range Mountains, Trinidad and Tobago).  Using a combination of cross-population and common-garden field approaches, augmented with controlled laboratory studies, we will address questions relating to the role of ecological variability in predation threats (both in space and time) on the selection for phenotypically plastic behavioural response patterns among prey populations. 

Theme 1: Is Neophobia a phenotypically plastic response to variable predation pressure?  Our recent work suggests that under conditions of high and variable predation threats, prey will exhibit increased predator avoidance towards novel chemosensory cues (neophobia).  We are conducting a combination of laboratory and field trials to assess: 1) if neophobia is a phenotpycially plastic trait within prey populations, 2) if this response to novel chemosensory cues is concentration dependent (i.e. threat-sensitive) or if the response is driven by background levels of threat, 3) if there exists ontogenetic contraints on neophobic predator avoidance and 4) if neophobic responses enhance or impair predator recognition learning.

Theme 2: Does uncertainty in local predation risk shape information use?  Damage-released chemical alarm cues are known to be highly conserved, both between species and between populations.  Given that they are released following mechanical damage inflicted by predators, alarm cues are highly reliable indicators of local risk, leasing to strong selection pressure on the cue receiver.  However, alarm cues represent a known level of threat; novel chemical cues or the cues of sympatric het erospecifics might be seen as an ‘uncertain’ cue.  We are conducting primarily field based trials to examine the effects of variable predation risk on the use of known vs. unknown chemical cues.  Specific questions include: 1) do prey value conspecific vs. heterospecific cues differently under high vs. low predation risk conditions? 2) does the use of known vs. unknown cues vary with ontogeny or life history stage? and 3) do different forms of chemosensory cues convey quantitatively different information?

Theme 3: Manipulating perceived risk to enhance post-stocking survival among hatchery-reared juvenile salmonids.  Each year, millions of hatchery-reared salmon are released as part of stock enhancement programs through Canada.  However, due to a lack of ecologically relevant experience (coupled with ‘hatchery selection’), an unacceptably high proportion of these fish are preyed upon.  Using field and laboratory studies, we are testing the hypothesis that manipulating the perception of predation risk among hatchery fish will increase their ability to detect and respond to local predation threats.  Specfic questions include: 1) does elevated risk of predation induce neophobic predator avoidance in hatchery-reared salmonids? 2) does induced neophobia persist long enough to allow for enhanced post-stocking survivial? 3) can prey fish be conditioned to recognize common predators prior to stocking? and 4) can we apply the findings of ecologically relevant learning mechanisms to these conditioning paradigms?

 

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