Predator diet cues and the assessment of predation risk by juvenile brook charr: do diet cues enhance survival?

2003 ◽  
Vol 81 (1) ◽  
pp. 126-132 ◽  
Author(s):  
Reehan S Mirza ◽  
Douglas P Chivers

Recent studies have shown that predator diet cues provide important information that prey animals can use to assess predation risk. Predator-naïve prey animals may even learn to recognize unknown predators when they detect conspecific cues in the predator's diet. We examined the importance of predator diet cues in the responses of juvenile brook charr (Salvelinus fontinalis) to chemical cues of predators. In our first experiment, we showed that charr respond to chemical cues of adult yellow perch (Perca flavescens) that were fed a diet of either brook charr or rainbow trout (Oncorhynchus mykiss), but not to perch fed a diet of brook stickleback (Culaea inconstans). Responses to diet cues from perch fed both charr and trout may indicate that charr are responding to evolutionarily conserved salmonid alarm cues in the predator's diet. In a second experiment, we exposed charr to chemical cues from predatory northern pike (Esox lucius) that were fed charr, trout, or stickleback. Live-predation trials revealed that charr exposed to diet cues from pike fed salmonids exhibited higher survival than charr exposed to diet cues from pike fed a non-salmonid. These results are the first to document a survival benefit for prey exhibiting behavioural responses to predator diet cues.

Behaviour ◽  
2001 ◽  
Vol 138 (10) ◽  
pp. 1249-1258 ◽  
Author(s):  
Reehan Mirza ◽  
Douglas Chivers

AbstractThe mechanisms that drive the evolution of intraspecifc predation (cannibalism) are unclear. Many authors speculate that predators can make substantial gains in nutrition and reproductive output by consuming conspecifics. However, by consuming conspecifics, predators may risk decreasing their inclusive fitness by consuming kin or increasing the chances of pathogen transmission. In fishes intraspecific predation is typically observed when resource levels are low. During these periods it is important for prey fishes to be able to accurately assess their level of predation risk from cannibalistic conspecifics. Prey animals may be able to do this by using chemical cues available in the predator's diet. The last meal consumed by the predator may give important information for prey animals to assess predation risk. We exposed juvenile yellow perch, Perca flavescens, to chemical cues of adult perch fed a diet of either juvenile perch, spot tail shiners, Notropis hudsonius, swordtails, Xiphophorus helleri, or a control of distilled water. Spot tail shiners and juvenile perch commonly form mixed species shoals and are vulnerable to the same suite of predators. Swordtails do not co-occur with yellow perch or spot tail shiners. We found that juvenile perch increased shelter use significantly more when exposed to chemical cues of adult perch fed juvenile perch or spot tails, compared to adult perch fed swordtails or those exposed to distilled water. This suggests that the level of chemosensory assessment used by juvenile perch is quite sophisticated and that the antipredator response can be mediated by specific cues in the predator's diet. This study is the first to demonstrate a response of a fish to chemical cues from intraspecific predators. Future studies should examine the importance of predator diet cues in responses to chemical cues from intraspecific predators.


1989 ◽  
Vol 67 (2) ◽  
pp. 418-420 ◽  
Author(s):  
Clifford L. K. Robinson

I determined experimentally the relative survival of similar-sized yellow perch (Perca flavescens), brook stickleback (Culaea inconstans), fathead minnow (Pimephales promelas), and finescale dace (Phoxinus neogaeus), individually and in all possible species combinations, in the presence of northern pike (Esox lucius). Overall, perch showed the highest, sticklebacks and dace the intermediate, and fatheads the lowest relative survival. Differential laboratory survival of prey demonstrates the utility of single species experiments in predicting the results of multiple prey and predator interactions. The results also support the hypothesis that piscivory can maintain the distinctness of assemblages of predation-tolerant and piscivorous species versus assemblages of predation-intolerant species.


Behaviour ◽  
2002 ◽  
Vol 139 (7) ◽  
pp. 929-938 ◽  
Author(s):  
Douglas Chivers ◽  
Reehan Mirza ◽  
Jeffery Johnston

AbstractNumerous species of aquatic animals release chemical cues when attacked by a predator. These chemicals serve to warn other conspecifics, and in some cases heterospecifics, of danger, and hence have been termed alarm cues. Responses of animals to alarm cues produced by other species often need to be learned, yet mechanisms of learned recognition of heterospecific cues are not well understood. In this study, we tested whether fathead minnows (Pimephales promelas) could learn to recognize a heterospecific alarm cue when it was combined with conspecific alarm cue in the diet of a predator. We exposed fathead minnows to chemical stimuli collected from rainbow trout, Oncorhynchus mykiss, fed a mixed diet of minnows and brook stickleback, Culaea inconstans, or trout fed a mixed diet of swordtails, Xiphophorous helleri, and stickleback. To test if the minnows had acquired recognition of the heterospecific alarm cues, we exposed them to stickleback alarm cues and introduced an unknown predator, yellow perch (Perca flavescens) or northern pike (Esox lucius). 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 demonstrate that minnows can learn to recognize heterospecific alarm cues based on detecting the heterospecific cue in combination with minnow alarm cues in the diet of the predator. Ours is the first study to demonstrate that behavioural responses to heterospecific chemical alarm cues decreases the probability that the prey will be attacked and captured during an encounter with a predator.


1994 ◽  
Vol 51 (7) ◽  
pp. 1629-1633 ◽  
Author(s):  
Mark V. Abrahams

Experiments were conducted with fathead minnow (Pimephales promelas) and brook stickleback (Culaea inconstans) to determine whether their relative feeding rates were affected by risk of predation. Six groups of both species were observed foraging for food provided by an automated feeder while two parameters were manipulated: the presence or absence of a predator, yellow perch (Perca flavescens), and clear or turbid water. It was hypothesized that the armour and spines of brook stickleback would be of greatest benefit during a direct encounter with a predator. I attempted to simulate this condition with turbid water and predator present. Feeding rates of the two species were significantly different, with fathead minnow feeding at a greater rate than brook stickleback in the absence of a predator. In the presence of a predator the feeding rate of fathead minnow declined significantly whereas that of brook stickleback was unaffected. This resulted in similar feeding rates for the two species in the presence of a predator. Results demonstrate that risk of predation can alter the relative competitive abilities of two species in situations where one species possesses a morphological adaptation against predation. In the absence of predators, these traits may be detrimental in interspecific competition for food.


1995 ◽  
Vol 73 (10) ◽  
pp. 1951-1959 ◽  
Author(s):  
Charles H. Jagoe ◽  
Dave A. Welter

Chromosome number and genomic DNA content vary widely among fish species, and ploidy can vary within species. This suggests that the size, shape, and morphological features of cell nuclei may also vary. Nucleated erythrocytes of fish are an easily sampled homogeneous population of differentiated cells ideal for inter- and intra-species comparisons. We collected blood samples from largemouth bass (Micropterus salmoides), bluegill (Lepomis macrochirus), chain pickerel (Esox niger), yellow perch (Perca flavescens), mosquitofish (Gambusia holbrooki), redeye bass (Micropterus coosae), and rainbow trout (Oncorhynchus mykiss) and removed cytoplasm and nuclear membranes from blood cells. Individual nuclei were examined and measured using scanning electron microscopy and a computerized image analysis system, and inter- and intra-species differences evaluated by nested analysis of variance. Nuclear size and shape varied significantly among species. Isolated nuclei had conspicuous apertures or holes, and the number and size of these holes also varied significantly among species. Variations in nuclear size and structure within species were small compared with interspecies differences. Little is known of the ultrastructure of erythrocyte nuclei in lower vertebrates, but their structure differs considerably from that of other vertebrate non-erythroid cells, suggesting that the organization of their DNA and associated proteins may be different.


1971 ◽  
Vol 49 (3) ◽  
pp. 343-352 ◽  
Author(s):  
Joseph S. Nelson ◽  
F. Mervyn Atton

Brook sticklebacks, Culaea inconstans (Kirtland), are known from 20 locations in Alberta and Saskatchewan in which a high proportion of the individuals lack all or part of the pelvic skeleton. These locations are interspersed and surrounded by other locations containing individuals with a normal pelvic skeleton. Individuals which lack the skeleton are of both sexes and are fertile in at least one of the lakes.Considerable variation exists between locations in the proportion of individuals with and without the pelvic skeleton. Morphological intermediates are known from most of the 20 locations and virtually all degrees of pelvic skeleton formation exist between its absence and its full development. Little or no gradation exists, however, in pelvic spine length between their absence and presence. Although the pelvic spines are the first part of the pelvic skeleton to appear during ontogeny, they are present only in intermediates with a virtually complete skeleton base. In addition, many intermediates are highly asymmetrical in their pelvic skeleton while development during the ontogeny of normal individuals is symmetrical.There is a greater tendency for individuals in which the pelvic skeleton is deficient to occur in lakes which lack an outlet rather than to occur in lakes with a permanent outlet. An unusually high proportion of the lakes with these aberrant individuals have been subject to fishery management activities (fish introduction and poisoning), but these disturbances are not causing the loss of the pelvic skeleton.


2021 ◽  
pp. 1-11
Author(s):  
Catherine Chuirazzi ◽  
Melissa Ocampo ◽  
Mizuki K. Takahashi

Abstract Diet quality and predation are two critical factors in determining the growth and development of organisms. Various anurans are susceptible to phenotypic changes influenced by these factors. Yet, few studies examined prey diet quality as potential influence over predator-induced traits. Using wood frog tadpoles (Lithobates sylvaticus) as a model species, we investigated the effects of three diet compositions (plant-based, animal-based, omnivorous) crossed with presence or absence of chemical cues from predatory dragonfly larvae (Aeshnidae). After 35 days, we recorded 11 morphological measurements, Gosner stage, and intestinal length of tadpoles to assess phenotypic changes under the six different experimental conditions. Our results showed the additive effects of both diet quality and predator chemical cue without detection of interactions between the two. Tadpoles receiving the omnivorous diet grew and developed faster with wider denticle rows than those receiving the plant or animal diets. The growth and development of tadpoles receiving only the animal diet were significantly hindered. These results emphasize the importance of diet quality in the growth and development of larval wood frogs. Chemical cues from predators significantly reduced tadpole body size but, in contrast to previous findings, did not affect tail size. Our experimental procedure of providing water containing predator and injured conspecific chemical cues on a weekly basis likely provided relatively weak predation risk perceived by tadpoles compared to previous studies using caged predators. The predator environment in our experiment, however, represents one ecologically relevant scenario in which predation risk is not urgent.


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