Allopatric Predator Research Articles

Bigger doesn\u2019t mean bolder: behavioral variation of four wild rodent species to novelty and predation risk following a fast-slow continuum

BackgroundUnderstanding how wild species respond to novel situations with associated risk can provide valuable insights for inter-specific behavioral variation and associations with pace-of-life (POL). Rodents, a globally distributed and diverse taxonomic group, have been the subjects of countless studies emulating risky situations. Controlled laboratory experiments with a focus on wild-caught species provide the opportunity to test fine-scale behavioral responses to contexts of risk with ecological implications. For example, assessing the importance of predator cues eliciting antipredator responses, as well as whether wild rodents embody behavioral plasticity and repertoires, illustrated by habituation and variation in behavioral traits, respectively.ResultsIn this comparative study, we examined multiple behavioral responses of four rodent species in eastern Taiwan (three native species Mus caroli, Apodemus agrarius, Rattus losea, and one invasive, Rattus exulans) exposed to an unfamiliar microenvironment and novel cue from an allopatric predator, the leopard cat (Prionailurus bengalensis). All wild-caught animals were subjected to two consecutive nights of experimental trials in a laboratory setting. Behavioral responses to a novel situation during the first trial differed between species; smaller species investing more time in non-defensive behaviors compared to the larger species. More specifically, the smaller species M. caroli and A. agrarius allocated more time to exploration and foraging, whereas the larger rat species R. exulans and R. losea spent more time motionless or concealing. During the second trial, the addition of leopard cat cues did not elicit antipredator behaviors, but rather, rodents were found to exhibit increased non-defensive behaviors, specifically foraging efforts.ConclusionsOur results suggest that these four species do largely follow a behavioral fast-slow continuum with the two smaller mice species demonstrating increased boldness in a novel context compared to the larger rat species. Also, the wild populations of rodents in eastern Taiwan may be naïve to leopard cats. Finally, the rodents in our study demonstrated habituation to the microenvironment, indicating they possess adaptive capacity.

Zebrafish Adjust Their Behavior in Response to an Interactive Robotic Predator.

Zebrafish (Danio rerio) constitutes a valuable experimental species for the study of the biological determinants of emotional responses, such as fear and anxiety. Fear-related test paradigms traditionally entail the interaction between focal subjects and live predators, which may show inconsistent behavior throughout the experiment. To address this technical challenge, robotic stimuli are now frequently integrated in behavioral studies, yielding repeatable, customizable, and controllable experimental conditions. While most of the research has focused on open-loop control where robotic stimuli are preprogrammed to execute a priori known actions, recent work has explored the possibility of two-way interactions between robotic stimuli and live subjects. Here, we demonstrate a “closed-loop control” system to investigate fear response of zebrafish in which the response of the robotic stimulus is determined in real-time through a finite-state Markov chain constructed from independent observations on the interactions between zebrafish and their predator. Specifically, we designed a 3D-printed robotic replica of the zebrafish allopatric predator red tiger Oscar fish (Astronotus ocellatus), instrumented to interact in real-time with live subjects. We investigated the role of closed-loop control in modulating fear response in zebrafish through the analysis of the focal fish ethogram and the information-theoretic quantification of the interaction between the subject and the replica. Our results indicate that closed-loop control elicits consistent fear response in zebrafish and that zebrafish quickly adjust their behavior to avoid the predator's attacks. The augmented degree of interactivity afforded by the Markov-chain-dependent actuation of the replica constitutes a fundamental advancement in the study of animal-robot interactions and offers a new means for the development of experimental paradigms to study fear.

Innate response based on visual cues of sympatric and allopatric predators in Nile tilapia

Predators are an important selective pressure for prey, and responses to visual exposure to non-predators and to allopatric and sympatric predators may assist the understanding of how prey animals recognize and distinguish potential threats. Here, we visually exposed predator-naïve Nile tilapia (Oreochromis niloticus) to aquaria with only water (handling-negative control), a non-predator fish (Cyprinus carpio), a South American catfish (Pseudoplatystoma coruscans, allopatric predator), and an African catfish (Clarias gariepinus; sympatric predator). We found that Nile tilapia displayed antipredator responses to both predator catfish but not to non-predator fish or negative control conditions. These antipredator responses, however, were stronger to the sympatric catfish in comparison to the allopatric animal. We concluded that Nile tilapia is able to innately distinguish between a sympatric and an allopatric predator based on visual cues. We assume that the innate recognition of the allopatric predator could be attributed to similarities in the body morphology and movement (key stimuli) of the South American and African catfish. Although this is plausible, the mechanism of the innate allopatric recognition remains unknown and deserves future investigation.

The Braveheart amphipod: a review of responses of invasiveDikerogammarus villosusto predation signals

Predator pressure is a fundamental force driving changes at all levels of the community structure. It may protect native ecosystems from alien species. Therefore, resistance to diverse predators resulting from a universal anti-predator strategy seems crucial for invasion success. We present a comprehensive review of the responses of an invasive amphipod Dikerogammarus villosus to sympatric and allopatric predator signals. We summarize diverse aspects of the gammarid anti-predator strategy, including predator identification, morphological and behavioural adaptations, effectiveness of shelter use and resistance to indirect predator effects. The response of D. villosus is independent of predator species (including totally allopatric taxa), which assures the high flexibility of its predator recognition system. It has a harder exoskeleton and better capability of utilizing shelters compared to other gammarids, resulting in relatively high resistance to predators. Therefore, it can use predator kairomones as indirect food signals (sharing the diet with the predator) and follow the predator scent. This resistance may allow D. villosus to reduce the costs of its physiological responses to predators and sustain growth in their presence. This might facilitate invasion success by increasing its competitive advantage.

Naive tadpoles do not recognize recent invasive predatory fishes asdangerous.

Invasive alien predators (IAP) are spreading on a global scale-often with devastating ecological effects. One reason for their success may be that prey species fail to recognize them due to a lack of co-evolutionary history. We performed a comprehensive test of this "prey naiveté" hypothesis using a novel approach: we tested whether predator-naive tadpoles of the agile frog (Rana dalmatina) display antipredator behavior upon encountering chemical cues produced by native, invasive (established or recent) or allopatric fishes (four perciforms, four siluriforms, and two cypriniforms). We studied the influence of population origin on predator-detection ability by presenting chemical cues to predator-naive tadpoles that originated from fishless hill-ponds or fish-infested floodplain populations. Before trials, we fed fishes with tadpoles or an alternative food to test whether direct chemical cues from the predator's diet influences the tadpoles' recognition of potential predators. Tadpoles reduced their activity upon exposure to cues from native and long-established invasive perciforms, but not in response to recent invaders, allopatric predators, or to any siluriforms. Also, predators that were previously fed with tadpoles did not universally induce behavioral defensedefenses upon first encounter. Finally, tadpoles originating from isolated hill-ponds exhibited higher baseline activity and responded in weaker fashion than their conspecifics from floodplain populations, which co-exist with predatory fishes. Our results indicate that tadpoles may be vulnerable to invading predatory fishes due to their inability to recognize them as dangerous, though their ability to recognize invasive IAP may evolve rapidly, in fewer than 30 generations.

Predator diet, origin or both? Factors determining responses of omnivorous amphipods to predation cues

Detection of chemical cues of predators and food resources is a key for the behaviour of many species in aquatic ecosystems. We checked whether predator origin and diet, containing potential food and/or alarm signals, affect the behaviour of omnivorous prey partly sharing their diet with a top predator. We conducted y-maze experiments to study the responses of invasive omnivorous and cannibalistic amphipods (Dikerogammarus villosus and Pontogammarus robustoides) to chemical cues of fish predators, injured amphipods and chironomid larvae (common amphipod food). As the predators, we used the goby Babka gymnotrachelus (sympatric with the amphipods) and piranha Pygocentrus nattereri (allopatric to the amphipods). The fish were either starved or fed amphipods or chironomids. D. villosus preferred predators fed chironomids and conspecifics as well as crushed conspecifics and chironomids, but avoided both hungry predators. Thus, D. villosus may perceive the presence of a top predator as an indication of both food resource and predation risk. P. robustoides avoided predators fed both amphipods (particularly conspecifics) and their alarm substances. The responses of both species depended more on the predator diet than on its species, which is likely to facilitate the recognition of allopatric predators and survival in newly invaded areas.

No longer naïve? Generalized responses of rabbits to marsupial predators in Australia

Predation is an important selective force on prey species, but avoiding predators can be costly. Efficient decisions on who to avoid (predator recognition) and when (situations with different predation risk) will determine the chances of prey survival. In coevolved predator-prey systems, detection of predator odours generally induces a response in potential prey to reduce predation risk. However, prey may not necessarily respond to odours of predators with which they have no previous experience, as predicted by the prey naivete hypothesis. In turn, perceived predation risk may also modulate predator recognition and the intensity of antipredator responses. In this study, we investigate the responses of an introduced prey species, the European rabbit (Oryctolagus cuniculus), to odours from coevolved and non-coevolved, sympatric and allopatric predators in situations of high and low numbers of predators in Australia. We used pellet counts to quantify rabbits’ use of space on experimental plots treated with predator odours. Rabbit avoidance of plots scented with coevolved predator odours was strongest, but they also responded to non-coevolved, marsupial predators. Predator abundance did not affect predator recognition in rabbits, although responses were more intense in situations where perceived predation risk was low and the intensity of responses decreased over time. Our results suggest that rabbits may have learned to recognize novel marsupial predators after 150 years of exposure in their introduced range.

Behavioural responses of feral and domestic guppies (Poecilia reticulata) to predators and their cues

Predation is an important factor during adaptation to novel environments, and the feralisation of introduced domestic species often involves responding appropriately to allopatric predators despite a background of domestication and inbreeding. Twenty years ago, domestic guppies were introduced to a semi-natural environment at Burgers’ Zoo in the Netherlands, where they have since been exposed to avian predation. We compared predation-linked behaviours in this feral population and in domestic guppies akin to the original founders. We found that both populations responded to a novel predator and to conspecific alarm cues. However, shoaling, an important anti-predator behaviour, was higher among feral guppies both at baseline and when exposed to the novel predator. We did not observe a linked suite of anti-predator behaviours across shoaling, predator inspection, alarm substance sensitivity and boldness, suggesting that these responses may be decoupled from one another depending on local predation regimes. As we compared two populations, we cannot identify the causal factors determining population differences, however, our results do suggest that shoaling is either a particularly consequential anti-predator adaptation or the most labile of the behaviours we tested. Finally, the behavioural adaptability of domestic guppies may help to explain their success as an invasive species.

Live predators, robots, and computer-animated images elicit differential avoidance responses in zebrafish.

Emotional disturbances constitute a major health issue affecting a considerable portion of the population in western countries. In this context, animal models offer a relevant tool to address the underlying biological determinants and to screen novel therapeutic strategies. While rodents have traditionally constituted the species of choice, zebrafish are now becoming a viable alternative. As zebrafish gain momentum in biomedical sciences, considerable efforts are being devoted to developing high-throughput behavioral tests. Here, we present a comparative study of zebrafish behavioral response to fear-evoking stimuli offered via three alternative methodologies. Specifically, in a binary-choice test, we exposed zebrafish to an allopatric predator Astronotus ocellatus, presented in the form of a live subject, a robotic replica, and a computer-animated image. The robot's design and operation were inspired by the morphology and tail-beat motion of its live counterpart, thereby offering a consistent three-dimensional stimulus to focal fish. The computer-animated image was also designed after the live subject to replicate its appearance. We observed that differently from computer-animated images, both the live predator and its robotic replica elicited robust avoidance response in zebrafish. In addition, in response to the robot, zebrafish exhibited increased thrashing behavior, which is considered a valid indicator of fear. Finally, inter-individual response to a robotic stimulus is more consistent than that shown in response to live stimuli and animated images, thereby increasing experimental statistical power. Our study supports the view that robotic stimuli can constitute a promising experimental tool to elicit targeted behavioral responses in zebrafish.

Effectiveness of zebra mussels to act as shelters from fish predators differs between native and invasive amphipod prey

Biological invasions cause organisms to face new predators, but also supply new anti-predator shelters provided by alien ecosystem engineers. We checked the level of anti-predator protection provided to three gammarid species by an invasive Ponto-Caspian zebra mussel Dreissena polymorpha, known for its habitat modification abilities. We used gammarids differing in their origin and level of association with mussels: Ponto-Caspian aliens Dikerogammarus villosus (commonly occurring in mussel beds) and Pontogammarus robustoides (not associated with mussels), as well as native European Gammarus fossarum (not co-occurring with dreissenids). The gammarids were exposed to predation of two fish species: the racer goby Babka gymnotrachelus (Ponto-Caspian) and Amur sleeper Perccottus glenii (Eastern Asian). This set of organisms allowed us to check whether the origin and level of association with mussels of both prey and predators affect the ability of gammarids to utilize zebra mussel beds as shelters. We tested gammarid survival in the presence of fish and one of five substrata: sand, macrophytes, stones, living mussels and empty mussel valves. D. villosus survived better than its congeners on all substrata, and its survival was highest in living dreissenids. The survival of the other gammarids was similar on all substrata. Both fish species exhibited similar predation efficiency. Thus, D. villosus, whose affinity to dreissenids has already been established, utilizes them as protection from fish predators, including allopatric predators, more efficiently than other amphipods. Therefore, the presence of dreissenids in areas invaded by D. villosus is likely to help the invader establish itself in a new place.

Effects of animated images of sympatric predators and abstract shapes on fear responses in zebrafish

Previously, zebrafish were shown to respond to the presence of a live predator, the sight of a live predator, moving computer images of a predator, and images of different moving objects in a context and stimulus specific manner. For example, zebrafish showed a robust antipredatory reaction towards a sympatric predator, the Indian leaf fish (Nandus nandus) but not towards an allopatric predator or sympatric or allopatric harmless fish species. In a subsequent study, however, we found zebrafish not to show avoidance in response to the image of another sympatric predator, Xenentodon cancila. The results implied that zebrafish may possess genetic predispositions that allow them to effectively evade at least certain sympatric predators without any prior exposure to them. However, it is not known whether zebrafish can respond to other sympatric predators with antipredatory reactions without any prior exposure to such predators. It is also not known whether such responses may be dependent upon, or idiosyncratic to, predator species. To answer these questions, we examined the effect of computer animated (moving) images of five different predator species all sympatric with zebrafish (Nandus nandus, Channa maculata, Xenentodon cancila, Mystus bleekeri, Chitala chitala) and of two abstract shapes (star and rectangle, also animated) on zebrafish behaviour. The results confirmed that the sight of N. nandus is an aversive stimulus and that the image of X. cancila is not. However, the results also revealed that images of three other species (C. maculata, M. bleekeri, C. chitala) and that of a rectangle induce even more robust aversive reactions than what is elicited by N. nandus. At this point we do not know what features of the images may be perceived as aversive by zebrafish or whether the observed behavioural responses would be adaptive or effective in nature. Nevertheless, we argue that image-presentation based fear paradigms will be useful in future translational research. We also conclude that it may be premature to decide whether zebrafish can recognize their sympatric predators.

Behavioral response of Norway rats (Rattus norvegicus) to odors of different mammalian species

Behavioral responses to the odors of three predators of rodents (domestic cat (Felis catus), weasel (Mustela sibirica), Eurasian badger (Meles meles)), one non-predator mammal (rabbit (Lepus capensis)), and distilled water (control) were assessed in three types of Norway rats (Rattus norvegicus): wild (WNRs), domestic (DNRs), and albino laboratory Wistar (AWRs). Rats were taken individually to a testing apparatus consisting of a hide box and a testing arena. The behavioral activities, including concealing, heading out, approaching, and feeding behaviors in each trial were videotaped for 3 h. Results revealed that WNRs, DNRs, and AWRs all showed an aversion to the predator odors by spending more time concealing in the hide box: frequencies of approaching and feeding behaviors, as well as the amount of food intake were significantly lower than control group. Our results suggest that the response of DNRs and AWRs were “built-in” or innate in nature as they had never experienced the odors of the tested predators. Moreover, all three types of rats can distinguish between predator and non-predator odors, but the ability of WNRs was the highest, which can distinguish between sympatric and allopatric predators, while the ability of AWRs was the lowest, which spent most time in the hide box. The concealing and approaching behaviors were no significantly different among the five odor exposure groups. Also, the reactions of the three types of rats toward the control group (distilled water) significantly differ. This suggests that the duration of time spent in captivity plays an important role in shaping the response of rats to different predator odors.

Sympatric predator detection alters cutaneous respiration in Lymnaea

The ability of an organism to detect a predator and then to take the appropriate vigilance actions is paramount for survival of the species. Lab-reared snails (> 250 generations) maintain their ability to detect predators and alter both aerial and cutaneous respiration. However, only the scent of a sympatric predator altered aerial respiration in freshly collected ‘wild’ snails. Here we test the hypothesis that the detection of a sympatric predator but not an allopatric predator will alter cutaneous respiration in freshly collected ‘wild’ snails. We find that Alberta snails while altering their cutaneous respiration to the scent of a sympatric predator (Tiger salamander) do not alter respiration to the scent of a crayfish (an allopatric predator). In Dutch snails there is a greater alteration to the scent of crayfish (sympatric predator) than to an allopatric predator (Tiger salamander).

Prey naiveté in an introduced prey species: the wild rabbit in Australia

Early detection of predators by their prey is an essential element of antipredator tactics, and for many mammalian predator prey interactions, detection comes mainly via a predators olfactory cues. The avoidance of predator odors can reduce the likelihood of encountering predators and increases the chances of prey survival. However, the role of coevolutionary history in the exploitation of odors in mammalian predator-prey interactions is not so well understood. The prey naivetehypothesis predicts the lack of effective antipredator behaviors given the lack of a coevolution between predator and prey but has so far been only tested on native prey. In this study, we describe the short-time responsiveness of an introduced prey species, the European rabbit (Oryctolagus cuniculus), to scents from coevolved and novel predators in Australia. We quantified rabbit activity rates by means of pellet counting and activity indices based on footprints, in a series of experimental plots treated with predator odors, and both methods yielded consistent results. Rabbits responded to coevolved predators by reducing their activity rates to scented exper- imental plots, whereas no avoidance was found for novel allopatric predators. These results suggest a shared evolutionary history between the antipredatory responses of rabbits and their natural predators. Key words: antipredator response, avoidance behav- ior, coevolutionary history, Oryctolagus cuniculus, predation, space use. (Behav Ecol)

Behavioral response of Nile tilapia to an allopatric predator

We investigated interaction of the Nile tilapia, Oreochromis niloticus, paired with either a predator, spotted sorubim, Pseudoplatystoma corruscans, or a nonpredator, threespot leporinus, Leporinus friderici. Fish behaviors were quantified 5 min before pairing and 15 min during pairing (a heterospecific fish introduced into the Nile tilapia aquarium). Distance from the heterospecific fish, frequency, and time spent in dorsal-fin display, and frequency of agonistic interactions were registered. Agonistic interaction occurred mainly between Nile tilapia and threespot leporinus. Pairing increased frequency and time spent in dorsal-fin display, mainly when tilapia was paired with the threespot leporinus. Tilapia kept further away from spotted sorubim than from threespot leporinus. We concluded that Nile tilapia discriminates a predator from a harmless nonpredator allopatric heterospecific, suggesting a genetically-based ability. The dorsal-fin display is interpreted as both anti-predatory (displayed to the predator spotted sorubim) and intimidator behavior (displayed to the threespot leporinus).

Zebrafish (Danio rerio) responds differentially to stimulus fish: The effects of sympatric and allopatric predators and harmless fish

The zebrafish has been an excellent model organism of developmental biology and genetics. Studying its behavior will add to the already strong knowledge of its biology and will strengthen the use of this species in behavior genetics and neuroscience. Anxiety is one of the most problematic human psychiatric conditions. Arguably, it arises as a result of abnormally exaggerated natural fear responses. The zebrafish may be an appropriate model to investigate the biology of fear and anxiety. Fear responses are expressed by animals when exposed to predators, and these responses can be learned or innate. Here we investigated whether zebrafish respond differentially to a natural predator or other fish species upon their first exposure to these fish. Naïve zebrafish were shown four species of fish chosen based on predatory status (predatory or harmless) and geographical origin (allopatric or sympatric). Our results suggest that naïve zebrafish respond differentially to the stimulus fish. Particularly interesting is the antipredatory response elicited by the zebrafish's sympatric predator, the Indian Leaf Fish, and the fact that this latter species exhibited almost no predatory attacks. The findings obtained open a new avenue of research into what zebrafish perceive as “dangerous” or fear inducing. They will also allow us to develop fear and anxiety related behavioral test methods with which the contribution of genes to, or the effects of novel anxiolytic substances on these behaviors may be analyzed.

Embryonic experience to predation risk affects tadpoles of the common frog (Rana temporaria)

Amphibians are known to exhibit phenotypic plasticity in response to variations in predation pressure. Data also indicate that developmental changes can be induced by embryonic exposures to predator non-contact cues. However, the possible consequences of such exposures on larval behavioural activity and sensitivity to chemical cues from predators have remained unexplored. These laboratory experiments examine the effects of predation cues experienced during embryonic development on some morphological and behavioural traits in hatchlings and tadpoles of the common frog (Rana temporaria). Eggs were raised until hatching in the nonlethal presence of either a sympatric predator (larval spotted salamander, Salamandra salamandra), or an allopatric predator (juvenile Turkish crayfish, Astacus leptodactylus), or crushed conspecific tadpoles. Predators were kept either starved, or fed with R. temporaria tadpoles. Embryonic treatments had significant consequences on weight and total length of hatchlings, as well as on the general activity of tadpoles. Olfactometric tests showed that the behavioural responses of tadpoles to chemical cues from the two predators tested were not significantly affected by embryonic treatments. In contrast, embryonic experience showed a significant influence on the behavioural response of tadpoles to chemical cues from crushed conspecifics. These results indicate that the morphology of hatchlings depends on the species and diet of the predators present during embryonic development and demonstrate for the first time that the subsequent activity and chemically mediated antipredator behaviour of tadpoles can be influenced by embryonic experience of the predation risk.

Biogeography of sponge chemical ecology: comparisons of tropical and temperate defenses

Examples from both marine and terrestrial systems have supported the hypothesis that predation is higher in tropical than in temperate habitats and that, as a consequence, tropical species have evolved more effective defenses to deter predators. Although this hypothesis was first proposed for marine sponges over 25 years ago, our study provides the first experimental test of latitudinal differences in the effectiveness of sponge chemical defenses. We collected 20 common sponge species belonging to 14 genera from tropical Guam and temperate Northeast Spanish coasts (Indo-Pacific and Mediterranean biogeographic areas) and conducted field-based feeding experiments with large and small fish predators in both geographic areas. We use the term global deterrence to describe the deterrent activity of a sponge extract against all of the predators used in our experiments and to test the hypothesis that sponges from Guam are chemically better defended than their Mediterranean counterparts. Sympatric and allopatric deterrence refer to the average deterrent activity of a sponge against sympatric or allopatric predators. All of the sponges investigated in this study showed deterrent properties against some predators. However, 35% of the sponge species were deterrent in at least one but not in all the experiments, supporting the idea that predators can respond to chemical defenses in a species-specific manner. Tropical and temperate sponges have comparable global, sympatric, and allopatric deterrence, suggesting not only that chemical defenses from tropical and temperate sponges are equally strong but also that they are equally effective against sympatric and allopatric predators. Rather than supporting geographic trends in the production of chemical defenses, our data suggest a recurrent selection for chemical defenses in sponges as a general life-history strategy.

Ventilatory frequency indicates visual recognition of an allopatric predator in naı̈ve Nile tilapia

Perceiving a possible predator may promote physiological changes to support prey ‘fight or flight’. In this case, an increase in ventilatory frequency (VF) may be expected, because this is a way to improve oxygen uptake for escape tasks. Therefore, changes in VF may be used as a behavioral tool to evaluate visual recognition of a predator threat. Thus, we tested the effects of predator visual exposure on VF in the fish Nile tilapia, Oreochromis niloticus. For this, we measured tilapia VF before and after the presentation of three stimuli: an aquarium with a harmless fish or a predator or water (control). Nile tilapia VF increased significantly in the group visually exposed to a predator compared with the other two, which were similar to each other. Hence, we conclude that Nile tilapia may recognize an allopatric predator; consequently VF is an effective tool to indicate visual recognition of predator threat in fish.

The Ontogeny of Antipredator Behaviour in Paradise Fish Larvae (Macropodus Opercularis). Ii. the Response To Chemical Stimuli of Heterospecific Fishes

Abstract The response of larval paradise fish to chemical stimuli from heterospecific fish was investigated. The behaviour of 15, 20 and 25 day old larvae was observed both in the presence and absence of the chemical stimuli and in the presence or absence of a predator model. Larvae decreased their swimming activity to a similar level both in the absence and in the presence of the model if they swam in water conditioned with chemical stimulus of the snakehead (Chana striata), a sympatric predator, or the crucian carp (Carassius carassius), a sympatric benthic feeder. Moreover, if the model was present larval paradise fish showed more fleeing and backing in the water conditioned by the sympatric snakehead and pike (Esox lucius) in comparison to water of allopatric predators and the sympatric crucian carp. Fleeing and backing increased with age in the case of snakehead stimulus. We conclude that larval paradise fish are capable of discriminating between waters conditioned by sympatric and allopatric fish in the presence of a simple predator model and this ability develops with age even without experience. The results support the hypothesis that larval fish rely more on non-specific avoidance of potential predators at the beginning of their development but their ability of discrimination emerges in parallel with the improvement of the motor skills that enable them to actively avoid and escape from predators.