Predator recognition learning in rainbow darters Etheostoma caeruleum: specific learning and neophobia

This study investigated whether rainbow darters Etheostoma caeruleum can learn to recognize unfamiliar predators through the process of classical conditioning. Etheostoma caeruleum were conditioned by exposing them simultaneously to their chemical alarm cues (a known fright stimulus) and either chemical cues from larval ringed salamanders Ambystoma annulatum (unfamiliar predator) or to a blank water cue (control). Conditioning could result in either specific learning of the A. annulatum cue or increased wariness in response to any novel cue (neophobia). To distinguish between these possibilities, E. caeruleum in both groups were exposed to either A. annulatum cues alone or to chemical cues from western rat snakes Pantherophis obsoletus (novel cue) 2 days after conditioning. Treatment (A. annulatum‐conditioned) E. caeruleum, but not control E. caeruleum, showed a fright response when they were exposed to both the conditioned (A. annulatum) and novel (P. obsoletus) cues, indicating increased sensitivity to new stimuli. When E. caeruleum were retested after an additional 32 days, however, the fright response occurred only following exposure to the conditioned (A. annulatum) stimulus, indicating that specific learning of the A. annulatum cue had been retained whereas the neophobia to novel stimuli was temporary.     

How weird can mimicry get?

Classical mimicry theory distinguishes clearly between the mutualistic resemblance between two or more defended species (muellerian mimicry), and the parasitic resemblance of a palatable species to a defended species (batesian mimicry). Modelling the behaviour of predators, without initially taking ecological complications into account, is a good strategy for exploring whether this division is valid. Two such behavioural models are described: conditioning theory, which simulates changes in motivational attack levels according to the norms of current learning theory; and saturation theory, which considers how a predator may become saturated with a particular toxic compound, and then cease feeding on the prey species that delivers it. This effect is to be clearly distinguished from simple satiation. Most formulations of the conditioning model allow the direction of reinforcement produced by a particular prey to change according the predator's current state of motivation: this leads to the existence of quasi-batesian mimicry, a parasitic mimicry between two species that could both be described as defended. At high densities, two prey species that share a chemical defense will be ‘muellerian mutualists’, mutually protecting each other against predators that have been saturated with the defensive compound. This mutualism may be accompanied by true muellerian mimicry of the colour patterns, or the patterns may be completely different. This can therefore be regarded as a form of mimicry in a non-visual communication channel. Even an apparently palatable prey species may be effectively unavailable to predators if its density is such as to deliver a particular nutrient in excess of the predator's need for a balanced diet. Such a nutrient in effect becomes a toxin, and such an abundant prey species would be partly defended and potentially able to act as the model in a mimicry system. Thus there might be protective mimicry between ‘palatable’ species, and a ‘palatable’ species might even function as the model for a ‘defended’ mimic. These unorthodox kinds of mimicry probably exist transiently during fluctuations of prey populations. It is less likely that these conditions persist for long enough to induce the evolution of mimicry, and the relationships perhaps usually occur when mimicry already exists for other reasons. Mimicry rings may be mutually stabilised by a combination of toxic mutualism and the exchange of species between the rings. Colour polymorphism in a defended species is strictly neutral whenever the population is dense enough to saturate the predator. This, as well as quasi-batesian mimicry, may help to explain the minority of warningly coloured species that are polymorphic. This revised version was published online in July 2006 with corrections to the Cover Date.     

Olfactory Conditioning of the Butterfly Agraulis vanillae (L.) (Lepidoptera, Nymphalidae) to Floral But Not Host-Plant Odors

The associative learning capacity of male and female nymphalid butterflies, Agraulis vanillae, was investigated. Both males and females were conditioned to chemical stimuli of amyl acetate and butyl acetate, but not of host-plant volatile emissions, although our EAG recordings demonstrate that Agraulis can detect host-plant aroma as well as both acetates. More female than male Agraulis were conditioned. Female butterflies reared in the laboratory generally exhibited a higher percentage of conditional responses than those collected in nature. The number of conditional responses on the first day of experiments was significantly smaller than on the ensuing 2–7 days.     

Occasion setting in Pavlovian ambiguous target discriminations

Rats were trained in a Pavlovian serial ambiguous target discrimination, in which a target cue was reinforced if it was preceded by one stimulus (P-->T+) but was not reinforced if it was preceded by another stimulus (N-->T-). Test performance indicated that stimulus control by these features was weaker than that acquired by features trained within separate serial feature positive (P-->T+, T-) and serial feature negative (N-->W-, W+) discriminations. The form of conditioned responding and the patterns of transfer observed suggested that the serial ambiguous target discrimination was solved by occasion setting. The data are discussed in terms of the use of retrospective coding strategies when solving Pavlovian serial conditional discriminations, and the acquisition of special properties by both feature and target stimuli.     

肥须亚麻蝇幼虫头咽骨形态学分析及其法医学意义

为了明确肥须亚麻蝇Parasarcophaga crassipalpis Macguart幼虫头咽骨形态学特征的变化规律,分别在16,20,24,28和32℃下饲养肥须亚麻蝇幼虫并定期取样,显微镜下观察其形态变化,利用图像分析软件测量其口钩和咽骨的面积、平均光密度及骨化面积等形态参数。结果显示:在所测量口钩和咽骨的7项指标中,咽骨的平均光密度及骨化面积是最理想的幼虫日龄的判断指标,对尸体上死后间隔时间的推测具有重要的指导意义;口钩部的4项指标在龄期更叠时有明显变化,仅可进行龄期的鉴别。     

Use of positive reinforcement conditioning to monitor pregnancy in an unanesthetized snow leopard (Uncia uncia) via transabdominal ultrasound

Closely monitoring snow leopard (Uncia uncia) fetal developments via transabdominal ultrasound, with minimal stress to the animal, was the goal of this project. The staff at Potter Park Zoo has used the principles of habituation, desensitization, and positive reinforcement to train a female snow leopard (U. uncia). Ultrasound examinations were preformed on an unanesthetized feline at 63 and 84 days. The animal remained calm and compliant throughout both procedures. Fetuses were observed and measured on both occasions. The absence of anesthesia eliminated components of psychologic and physiologic stress associated with sedation. This was the first recorded instance of transabdominal ultrasound being carried out on an unanesthetized snow leopard. It documents the feasibility of detecting pregnancy and monitoring fetal development via ultrasound. Zoo Biol 27:78–85, 2008. © 2007 Wiley‐Liss, Inc.     

Behavioral modification in choice process of Drosophila

Because of its clear genetic and developmental background, diversity of behavioral paradigms and neuroanatomy of the brain, Drosophila has become an important animal model for studying genetic, molecular and cellular bases of learning and memory[1]. Extensive research has explored the visual operant conditioning of Drosophila and related molecular bases[2—8]; recently, researchers began to address cognition-like functions and involved neural substrates[9—11]. In these studies, behavioral ana…     

Discriminative and reinforcing stimulus properties of music for rats

We trained rats to discriminate music by Bach from that by Stravinsky using operant conditioning. The rats successfully learned the discrimination and transferred their discrimination to novel music by the same artists. Then, we trained rats on concurrent-chain schedule in which the terminal links were associated with different music, Bach or Stravinsky. The rats did not show strong preference for either style of music, although one subject showed a preference for Bach and another subject preferred Stravinsky. Finally, we examined the validity of the concurrent-chain procedure as a method of preference measurement with conspecific vocalization evoked by an aversive experience. Most of the rats preferred white noise to the conspecific vocalization. Therefore, music has a discriminative stimulus property but not a clear reinforcing property for rats.     

Instrumental outcome devaluation with representation-mediated conditioning

In three experiments, rats were trained to perform two instrumental behaviours (R1 and R2) in the presence of discriminative stimuli (Sd1 and Sd2, respectively) to obtain a common food outcome (O1). Acquisition of the two discriminations was followed by switching the outcome accompanying R2 performance from O1 to a new one (O2). Experiment 1 showed paired presentations of O2 with a lithium chloride (LiCl) injection resulted in a reduction in the R2 performance. In the subsequent two experiments, each Sd was paired with LiCl injection and its effects on outcome consumption and instrumental performance were investigated. A reduction in the O2 consumption subsequent to the Sd devaluation was found in Experiments 2 and 3. Experiment 3 revealed a reduced R2 performance in an extinction test, following the animals’ consummatory access to the outcomes in training context. These results demonstrate representation-mediated outcome devaluation in the course of the Sd devaluation.