Predation response

Brown G. and Godin J. (1997). Anti-predator responses to conspecific and heterospecific skin extracts by Three-spined Sticklebacks alarm pheromones revisited. Behaviour 134, 1123-1134. 

Mirza and Chivers (in press) found that fathead minnows had the ability to learn to recognize a novel heterospecific odour as an indication of predation if the cue was present in the diet of a known predator. In their study, minnows were exposed to chemical stimuli collected from a tank containing a known predator (northern pike, Esox lucius) fed one of two unknown prey, stickleback or swordtails (Xiphophorous helleri). In subsequent behavioural tests, the minnows were exposed to either swordtail skin extract or stickleback skin extract. Minnows exposed to the odour of pike fed stickleback responded to stickleback skin extract with an anti-predator response but did not respond to swordtail skin extract. Similarly, minnows exposed to pike fed swordtail cues responded to swordtail skin extract with an antipredator response but did not respond to stickleback skin extract. This study demonstrated that minnows had the ability to learn to recognize a novel cue in the diet of a known predator, whether that cue is from a species that commonly co-occurs with minnows (the stickleback) or an allopatric tropical species with which it has never co-occurred. 

Chivers et al. (2002) tested whether or not learned responses could result in a survival benefit, besides confirming that fish could learn unknown heterospecific cues through the diet or a predator. In a two-part study, fathead minnows were exposed to chemical stimuli collected from rainbow trout (Oncorhynchus mykiss) fed a mixed diet of either minnows and brook stickleback, or swordtail and stickleback. To test if the minnows had acquired recognition of stickleback alarm cues, Chivers et al. (2003) exposed the fish to stickleback alarm cues and introduced an unknown predator, yellow perch or northern pike. Both perch and pike took longer to initiate an attack on minnows that were previously exposed to trout fed minnows and stickleback than those previously exposed to trout fed swordtails and stickleback. These results show again that fishes are able to learn novel cues through association with known cues in a predator s diet. Furthermore, it shows that anti-predator responses to these newly learned cues could result in a survival benefit. 

Most laboratory studies examining the responses of fishes to chemical alarm cues have shown that the anti-predator responses exhibited to conspecific cues are specific to conspecifics and are not generalized responses to any injured fish cue or any novel odor (Chivers and Smith, 1998). Consequently, most of the field tests have used distilled water as the control. However, more recently, several studies now include an unfamiliar heterospecific skin extract (usually swordtail, Xiphophorus helleri) or novel odors, such as morpholine, as additional controls. In some cases the results are somewhat surprising. 

Fishes exist in a complex context-dependent system that is based on multiple sensory inputs that could lead to a number of variable, yet appropriate, anti-predator responses. 

Field studies are necessary to validate anti-predator responses of prey fishes in the chemically complex natural environment. While several of the early trap experiments demonstrated the effectiveness of alarm cues in the field (i.e., Mathis and Smith, 1992), the more complicated recent studies often demonstrate no preferential avoidance between familiar and unfamiliar cues or, alternatively, results are contradictory to predictions. Trap experiments have therefore brought into question previous knowledge based primarily on laboratory studies (i.e., visual compensation model). Anti-predator defense strategies of fishes are clearly context-dependent. To decipher and explore the complexities of this dependent response further, field studies investigating the various biotic and abiotic factors affecting a fish s response are required. 

Our data emphasize the importance of including a temporal component when measuring behavioural responses to alarm cues. Conclusions based on a minute by minute analysis clearly demonstrate that fish exposed to higher concentrations of alarm cue will exhibit a longer duration response than those exposed to lower concentrations of alarm cues. This provides another line of evidence that fishes exhibit an anti-predator response that matches the threat. Had we used the average response of the fish during the... 

Sullivan, A. M., Maerz, J. C., and Madison D. M., 2002, Anti-predator response of red-backed sakunanders (Plethodon cinereus) to chemical cues fiom garter snakes (Thamnophis sirtalis) laboratory and field experiments. Behav. Ecol. Sociobiol. 51 227-233. 

We have attempted to place the documented studies into two categories dependent upon whether the predator consumes eggs or newly hatched larvae. Although for the most part this can be done, we still have to account for studies that do not fit neatly into our patterns. Moreover, we tend to see variability in the responses of the same species to different types of predators or different species to similar types of predator. Responses may be species specific. In one study, Chivers et al. (2001) show that Cascades fi g and treefixrg tadpoles hatch earlier when exposed to predatory leeches which are believed to be an egg predator. In another study, Schalk et al. (2002) find that green fi og tadpoles (R. clamitans) delay hatching in response to cues from predatory leeches that are also believed to be egg predators. 

Brown, G.E. R.J.F. Smith. 1997. Conspecific skin extracts elicit anti-predator responses in juvenile rainbow trout Oncorhynchus mykiss). Can. J. Zool, 75, 1916-1922... 

The alarm substance hypothesis cannot be excluded in our trials, but it can be rejected based on other studies. We have shown that red-backed salamanders do not avoid substrate traces from red-backed salamanders that have been induced to autotomize their own tail (a stress-induced, anti-predator response Arnold, 1988 Lancaster Wise, 1996), and other red-backed salamanders even attempt to eat the autotomized tails (Madison, unpublished). In addition, the broken skin of sacrificed red-backed salamanders fails to negate the chemosensory avoidance of substrates from garter snakes that had been fed red-backed salamanders (McDarby, 1997). 

One explanation for the partial dissociation observed and why avoidance scores were not more extreme during the day is that confinement in the test dishes could have forced the more active salamanders to cross between samples at such a rate that side avoidance was abolished. If a single rushed response from each salamander was the basis for the preference score, a dilution or cancellation effect could have occurred for some salamanders. However, since salamanders in our study had many opportunities to correct for crossings onto snake substrates, and since only 11 out of 20 positions on the water side were needed to count as an avoidance of snake substrate, any tendency to avoid substances on this substrate should have been expressed. In addition, the movements that occurred were not rushed, as in an escape ( anti-predator ) response, but slower deliberate actions with pauses and head movements typical of chemosensory investigation (reviewed by Jaeger, 1986). Thus, we conclude that space restrictions in the petri dishes did not abolish avoidance among the more active salamanders. 

The extent of color vision in the various groups of animals continues to be a matter of some controversy. Color vision is well-developed in insects, lizards, turtles, birds, and primates, but apparently in no other mammals. Reports of limited color vision are known for other vertebrate groups, but most workers in the field believe birds to be the primary predators responsible for mimicry with perhaps some importance played by lizards (Sexton etal., 1966 Boyden, 1976), primates (Cott, 1940), and amphibians (L. Brower etal., 1960). 

Brower, L. P., Cook, L. M. and Croze, H. J. (1967) Predator responses to artificial Batesian mimics released in a neotropical environment. Evolution, 21, 11-23. 

Hislop, R. G. and Prokopy, R. J. (1981) Mite predator responses to prey and predator-emitted stimuli. J. Chem. Ecol., 7, 895-904. 

The small proportion of (- )ipsdienol in the pheromone blend of 7. paraconfusus might similarly be advantageous in spite of it being the pheromone of its competitor, 7. pini, because (- )ipsdienol also appears to deter 7. latidens. The exploitation of pheromone components by predators need not necessarily select for different attractive blends but could result in selection for components that interrupt the predator response. For example, the highly specific response of T. chlorodia to exo-brevicomin from female D. brevicomis is interrupted by... 

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