Predation - Wikipedia
"In an ecosystem, predation is a biological interaction where a predator (an organism that is hunting) feeds on its prey (the organism that is attacked). Predators may or may not kill their prey prior to feeding on them, but the act of predation often results in the death of the prey and the eventual absorption of the prey's tissue through consumption. Thus predation is often, though not always, carnivory."
Searching PubMed for "predatory behavior" yielded 9,682 references:
Searching PubMed for "predatory behavior endocrinology" yielded 7 references:
[Neurochemistry of impulsiveness and aggression]. (Polish)
"Aggression is the most frequent social reaction among animals and men, and plays an important role in survival of the fittest. The change of social conditions in the course of development of human civilisation rendered some forms of aggression counter-adaptive, but the neurobiological mechanism of expression of aggression have not fundamentally changed in the last stages of human evolution.
The two different kinds of aggression: emotional, serving mainly as a threat, and rational, predatory, serving for the attainment of goal in the most effective way, have different anatomical and neurobiological background and reciprocally inhibit each other.
Aggression is modulated by several neurotransmitter and hormonal systems, of which the key role is seemingly played by testosterone, a hormone involved in domination behaviour, and serotonin, whose deficit results in increased impulsiveness."
See: Boys without Fathers .
Oxytocin tempers calculated greed but not impulsive defense in predator-prey contests.
See: Oxytocin .
Searching PubMed for "predatory behavior hunger" yielded 45 references:
Hypothalamic and extrahypothalamic substrates of predatory attack. Suppression and the influence of hunger.
"Electrical stimulation of medial hypothalamic and ventromedial hypothalamic areas of the cat brain stops the initiation of spontaneous predatory attack in cats, confirming similar evidence of other investigators. Furthermore, a new attack suppressing area, the mammillary bodies, was uncovered. Facilitation of predatory attack by hunger raised the electrical threshold for attack in the mammillary bodies. In addition, baseline levels of neural activity in attack suppressing brain areas prior to any brain stimulation were found to decrease when the cats were hungry and killing was facilitated and neural activity increased when the cats were on ad lib. feeding. These data support the hypothesis that modulation of excitability of neural systems functioning to suppress is involved in facilitation of attack behavior by hunger."
Published before we knew much about the endocrine system. Interesting from an historical point of view, but not very helpful.
Mouse killing induced by para-chlorophenylalanine injections or septal lesions but not olfactory bulb lesions is similar to that of food-deprived spontaneous killers.
"Mouse killing induced by septal lesions, olfactory bulb lesions, or parachlorophenylalanine (PCPA) injections was compared with that of sated or food-deprived spontaneous mouse-killing rats in order to evaluate whether the experimentally induced killing corresponds to killing that occurs spontaneously, which tends to be viewed as predatory.
On the first mouse kill, the intensity of the initial reaction to the mouse, the site of the initial attack, and the time required to kill by all groups were similar except that bulbectomized rats required longer to kill. Following the kill, only rats with septal lesions and bulbectomized rats bit the mouse significantly more than spontaneous killers.
With the second mouse kill, there was an increase in the intensity of the response to the mouse and a decrease in attack latency by all groups except the bulbectomized rats and the nondeprived spontaneous killers. When presented with a freshly killed mouse, rats with septal lesions attacked with the greatest intensity, but PCPA-injected rats and food-deprived spontaneous killers also attacked more intensely than nondeprived killers. When presented with a wad of cotton or a block of wood, there was little or no response from the animals of all groups.
It is argued that the mouse killing induced by septal lesions or PCPA injections may be due to an enhanced predatory tendency similar to that occurring in food-deprived spontaneous killers. In contrast, the mouse killing by bulbectomized rats cannot be inferred to be predatory because their attacks were of low intensity and involved repeated superficial bites rather than one or two well-directed forceful bites."
"food-deprived spontaneous killers also attacked more intensely than nondeprived killers"
Reasonable enough, but nothing specific about the endocrine system.
Effects of viscerosensory stimulation on hypothalamically elicited predatory behavior in cats
"Hypnogenic (HS) or arousing (AS) stimulations of the small intestine (INT), splanchnic (SPL), and vagal (VAG) nerves were used to modify the predatory behavior (PB) elicited by stimulating the lateral hypothalamus (LHS). HS induced EEG synchronization and sleep. AS aroused the cat from slow-wave sleep. LHS induced the cat to attack an anesthetized rat and bite its neck after an exploratory activity.
The following parameters of PB were determined: biting latency (BL), the interval between the beginning of LHS and the touching the rat by the cat's muzzle; exploratory time (ET), which begins with an environmental search and culminates in orienting toward the rat; attack time (AT), in which the cat stalks and bites the rat.
HS, delivered for 5, 10, 15 min to INT, SPL, and VAG prior to LHS, increased BL and ET and did not affect AT. AS, delivered for 10 s to INT or VAG prior to LHS, decreased BL by reducing ET. SPL AS shortened BL by decreasing both ET and AT. The viscerosensory effects on PB were decreased by increasing the intensity of LHS; a ferocious attack with BL less than 10 s was not influenced by either HS or AS. These results indicate that the viscerosensory influence can modify PB by inhibiting or facilitating the priming events of the attack."
Nothing about the endocrine system.
Complex state-dependent games between owls and gerbils.
"Predator-prey interactions are often behaviourally sophisticated games in which the predator and prey are players.
Past studies teach us that hungrier prey take higher risks when foraging and that hungrier predators increase their foraging activity and are willing to take higher risks of injury. Yet no study has looked at the simultaneous responses of predator and prey to their own and each other's hunger levels in a controlled environment.
We looked for evidence of a state-dependent game between predators and their prey by simultaneously manipulating the hunger state of barn owls, and Allenby's gerbils as prey. The owls significantly increased their activity when hungry. However, they did not appear to respond to changes in the hunger state of the gerbils. The gerbils reacted strongly to the owls' state, as well as to their own state when the risk was perceived as high. Our study shows that predator-prey interactions give rise to a complex state-dependent game."
Nothing about the endocrine system.
2011 13<45 Free PMC Article
Calling at a cost: elevated nestling calling attracts predators to active nests.
"Begging by nestling birds has been used to test evolutionary models of signalling but theory has outstripped evidence. Eavesdropping predators potentially impose a cost on begging that ensures signal honesty, yet little experimental evidence exists for such a cost at active nests because the use of artificial nests, long playback bouts and absence of parents may have exaggerated costs.
We broadcast short periods (1 h) of either nestling vocalizations or background noise at active white-browed scrubwren, Sericornis frontalis, nests. Nestlings called naturally during both treatments, allowing us to test whether elevated calling increases risk, a key but rarely tested assumption of evolutionary models.
Predators visited nests exclusively during periods of elevated calling. Furthermore, playbacks affected neither adult visits nor nestling activity, suggesting that calling alone attracted predators. Adults gave alarm calls and nestlings usually called less when predators approached nests. Predation risk to broods is, therefore, likely to fluctuate substantially over short periods of time, depending on nestling hunger and whether adults or young have detected predators.
This study confirms a present-day cost of nestling begging, demonstrates that this cost can be incurred over short periods and supports the importance of parent-offspring antipredator strategies in reducing predation risk."
Nothing about the endocrine system.
Plasticity of boldness in rainbow trout, Oncorhynchus mykiss: do hunger and predation influence risk-taking behaviour?
"Boldness, a measure of an individual's propensity for taking risks, is an important determinant of fitness but is not necessarily a fixed trait. Dependent upon an individual's state, and given certain contexts or challenges, individuals may be able to alter their inclination to be bold or shy in response. Furthermore, the degree to which individuals can modulate their behaviour has been linked with physiological responses to stress.
Here we attempted to determine whether bold and shy rainbow trout, Oncorhynchus mykiss, can exhibit behavioural plasticity in response to changes in state (nutritional availability) and context (predation threat). Individual trout were initially assessed for boldness using a standard novel object paradigm; subsequently, each day for one week fish experienced either predictable, unpredictable, or no simulated predator threat in combination with a high (2% body weight) or low (0.15%) food ration, before being reassessed for boldness.
Bold trout were generally more plastic, altering levels of neophobia and activity relevant to the challenge, whereas shy trout were more fixed and remained shy.
Increased predation risk generally resulted in an increase in the expression of three candidate genes linked to boldness, appetite regulation and physiological stress responses - ependymin, corticotrophin releasing factor and GABA(A) - but did not produce a significant increase in plasma cortisol. The results suggest a divergence in the ability of bold and shy trout to alter their behavioural profiles in response to internal and exogenous factors, and have important implications for our understanding of the maintenance of different behavioural phenotypes in natural populations."
"ependymin, corticotrophin releasing factor and GABA(A)"
Feeding performance of juvenile hatchery-reared spotted seatrout Cynoscion nebulosus.
"The feeding performance of individual hatchery-reared (HR) and wild juvenile spotted seatrout Cynoscion nebulosus was compared across a series of six 1·5 h feeding exposures over a 3 day period in a controlled experiment. The predation cycle served as a context for discerning feeding performance elements. The experimental design facilitated assessments of the effects of experience, motivation due to hunger or satiation and prey density and encounter frequency.
Although feeding success improved significantly across successive trials for both groups of C. nebulosus, wild C. nebulosus successfully captured and consumed significantly more Palaemonetes spp. prey and completed most performance metrics more efficiently than HR C. nebulosus. Total exposure time decreased with experience for both groups of C. nebulosus; however, HR C. nebulosus took longer to complete feeding exposures. Underpinning this difference was the time spent by HR C. nebulosus in non-search mode and for completing various foraging behaviours. Nevertheless, juvenile HR C. nebulosus exhibited sufficient foraging plasticity to switch from a pelleted diet to live novel prey."
Nothing about the endocrine system.
2015 5<45 Free PMC Article
Alterations of hippocampal place cells in foraging rats facing a "predatory" threat.
"Fear is an adaptive mechanism evolved to influence the primal decisions of foragers in "approach resource-avoid predator" conflicts. To survive and reproduce, animals must attain the basic needs (food, water, shelter, and mate) while avoiding the ultimate cost of predation. Consistent with this view, ecological studies have found that predatory threats cause animals to limit foraging to fewer places in their habitat and/or to restricted times. However, the neurophysiological basis through which animals alter their foraging boundaries when confronted with danger remains largely unknown.
Here, we investigated place cells in the hippocampus, implicated in processing spatial information and memory, in male Long-Evans rats foraging for food under risky situations that would be common in nature. Specifically, place cells from dorsal cornu ammonis field 1 (CA1) were recorded while rats searched for food in a semi-naturalistic apparatus (consisting of a nest and a relatively large open area) before, during, and after encountering a "predatory" robot situated remotely from the nest.
The looming robot induced remapping of place fields and increased the theta rhythm as the animals advanced toward the vicinity of threat, but not when they were around the safety of the nest. These neurophysiological effects on the hippocampus were prevented by lesioning of the amygdala. Based on these findings, we suggest that the amygdalar signaling of fear influences the stability of hippocampal place cells as a function of threat distance in rats foraging for food."
Amygdala and hippocampus, but nothing about the endocrine system.
Predator odor exposure increases food-carrying behavior in rats.
"To cover their energy demands, prey animals are forced to search for food. However, during foraging they also expose themselves to the risk of becoming the prey of predators. Consequently, in order to increase their fitness foraging animals have to trade-off efficiency of foraging against the avoidance of predation risk. For example, the decision on whether a found food piece should be eaten at the food source or whether it should be carried to a protective site such as the nest (food-carrying behavior), is strongly dependent on different incentive factors (e.g., hunger level, food size, distance to the nest). It has been shown that food-carrying behavior increases the more risky the foraging situation becomes.
Since predator odors are clearly fear-inducing in rats, we ask here whether the detection of predator odors in close proximity to the food source modulates food-carrying behavior. In the present study, the food-carrying behavior of rats for six different food pellet sizes was measured in a "low risk" and a "high risk" testing condition by presenting water or a fox urine sample, respectively, next to the food source. For both testing conditions, food-carrying behavior of rats increased with increasing food pellet weight. Importantly, the proportion of food-carrying rats was significantly higher during exposure to fox urine ("high risk") than when rats were tested with the water control ("low risk").
Taken together, these results demonstrate that food-carrying behavior of rats is increased by the detection of a predator odor. Our data also support the idea that such food-carrying behavior can be considered as a pre-encounter defensive response. "
Nothing about the endocrine system.
Genomic Response to Selection for Predatory Behavior in a Mammalian Model of Adaptive Radiation.
"If genetic architectures of various quantitative traits are similar, as studies on model organisms suggest, comparable selection pressures should produce similar molecular patterns for various traits. To test this prediction, we used a laboratory model of vertebrate adaptive radiation to investigate the genetic basis of the response to selection for predatory behavior and compare it with evolution of aerobic capacity reported in an earlier work.
After 13 generations of selection, the proportion of bank voles (Myodes [=Clethrionomys] glareolus) showing predatory behavior was five times higher in selected lines than in controls. We analyzed the hippocampus and liver transcriptomes and found repeatable changes in allele frequencies and gene expression.
Genes with the largest differences between predatory and control lines are associated with hunger, aggression, biological rhythms, and functioning of the nervous system. Evolution of predatory behavior could be meaningfully compared with evolution of high aerobic capacity, because the experiments and analyses were performed in the same methodological framework. The number of genes that changed expression was much smaller in predatory lines, and allele frequencies changed repeatably in predatory but not in aerobic lines. This suggests that more variants of smaller effects underlie variation in aerobic performance, whereas fewer variants of larger effects underlie variation in predatory behavior. Our results thus contradict the view that comparable selection pressures for different quantitative traits produce similar molecular patterns. Therefore, to gain knowledge about molecular-level response to selection for complex traits, we need to investigate not only multiple replicate populations but also multiple quantitative traits. "
"hippocampus and liver transcriptomes", but no mention of the endocrine system.