Behavioural Processes最新文献

The ability of nervous systems to filter out irrelevant and repetitive stimuli may prevent animals from becoming ‘saturated’ with excess information. However, animals must be particular about which stimuli to attend to and which to ignore, as mistakes may be costly. Using a comparative approach, we explored the effect of interstimulus interval (ISI) between repeated presentations of visual stimuli presented on a screen to test the decrease in responses (response decrement) of both Trite planiceps jumping spiders and untrained Columba livia pigeons, animals with comparable visual ability despite having structurally different visual systems and brain size. We used ISIs of 2.5 s, 5 s, 10 s, predicting that decreases in ISI would lead to progressively less responses to the stimuli. Following from previous work on T. planiceps, we also manipulated pigeon hunger level, finding that hungry birds were initially more responsive than sated pigeons, but the rate of decrease in responses to the stimulus did not differ between the two groups. While a clear response decrement was seen in both species across all conditions, shorter ISIs resulted in more dramatic response decrements, aligning with previous work and with the resource depletion theory posited in the human-based literature.

The maintenance of variation within natural populations is key for natural selection to operate. Polymorphism is an intriguing form of variation that involves the persistence of multiple discrete phenotypes called morphs. Polymorphism is often explained by negative frequency dependent selection (NFDS), under which rare morphs have an advantage, such that no one morph takes over. We tested whether mating polymorphism is maintained by NFDS generated by female choice, in the livebearing poeciliid fish, Girardinus metallicus, whose males are either common, plain morphs or rare, black morphs. Females were treated with one morph for several weeks and tested with both, in mate choice and direct competition assays. Contrary to NFDS via female choice, females preferred the morph with which they were treated. This may disrupt the polymorphism given the rarity of black morphs in the wild, unless black morphs have other advantages: we found that black morphs tended to exhibit higher mating activity, and other studies have demonstrated that they are more aggressive. Interestingly, only black morphs display to females prior to copulation; however, there is little evidence for female preference for this morph or the mating display. These results suggest functions for the mating display of black morphs beyond courtship, including aggressive mate guarding, and prompt a discussion of what constitutes courtship behavior.

Inter-individual distance (IID) is an important indicator of social organisation because solitary species are spatially intolerant towards conspecifics, whereas group-living species are usually gregarious with collective behaviour. Therefore, by examining the relationship between the distribution of IIDs and the active space of cues or signals, and behaviours, we can predict their social organisation. The narrow-ridged finless porpoises (NRFPs) have been described as a solitary species; however, recent studies described NRFPs tend to live in groups more than alone. To resolve the inconsistency, the present study investigated IIDs, the active spaces of sounds, and behaviours. The distribution of IIDs measured using drone was classified into three distributions. The close and intermediate distributions were significantly shorter than the distribution predicted by the angle of drone camera, whereas the far distributions were not. The far distributions were thus a random distribution within the limited angle of the camera. The close distributions were shorter than the active space, exhibiting a high proportion of collective behaviours, while intermediate distributions did not. These results suggest that NRFPs have both solitary- and group-living characteristics. Specifically, the intermediate distribution suggests a solitary aspect to maintain IIDs from others, while the close distribution indicates a group-living aspect with social interactions.

A first approximation to the study of learning processes in bivalves is presented. A habituation procedure was developed using the slimy clam Ruditapes decussatus. The percentage of siphon withdrawal when they were exposed to a white light was measured. In Experiment 1, a habituation-discrimination procedure was used to study the stimulus intensity effect (350-lm vs 806 lm). Clams exposed to 350-lm showed a faster habituation than those exposed to 806-lm. Experiment 2 studied the effect of stimulus and intertrial interval (ITI) duration using a 2×2 design. Trials lasted 20 or 180 seconds, and the ITI lasted 5 or 10 minutes. A combined effect of these two parameters was obtained. Habituation was faster in clams exposed to 180-sec trials with a 5-min ITI. Finally, in Experiment 3 clams were trained with five blocks of five trials with a 5-min ITI. Groups differed on trial duration (20 or 180 s). The results showed a general spontaneous recovery effect that was more pronounced for the 180 s group. Also, it was found in this experimental condition a reduced response 24 hours after finishing training (long-term habituation). Altogether, this series of experiments constitutes a first systematic demonstration of habituation in bivalves.

The present study examined two procedures for assessing the discounting of delayed, hypothetical, monetary losses: the Adjusting-Amount procedure (Estle et al., 2006) and the Delayed Losses Questionnaire (Myerson et al., 2017), which was modeled on Kirby et al.’s (1999) delayed reward Monetary Choice Questionnaire. Of interest was whether these two procedures assess the same underlying construct. Online participants (N = 431) completed both the Adjusting-Amount procedure and the Delayed Losses Questionnaire. Results revealed that regardless of the delayed amount and whether the discounting measure used was atheoretical (area under the curve and immediate-choice proportion) or theoretically based (log k), the discounting on the Adjusting-Amount procedure was highly correlated with the discounting on the Delayed Losses Questionnaire (all r > .72). In addition, most of the participants (72.2 %) who showed one type of discounting pattern on one procedure (e.g., who increased choice of the larger payment with increases in its delay or who always chose the immediate payment) showed the same pattern on the other procedure. These findings are consistent with the hypothesis that the loss discounting procedures and measures studied here all assess the same construct.

This study examined the effects of different response-speed requirements on resistance to change. Undergraduates were exposed to a simulated scenario aiming to destroy pollution sources by clicking on moving targets. During baseline, a multiple variable interval (VI) 15 s VI 15 s was in effect. Points (100) served as reinforcers. In the Low-Speed Component, the response button moved across the computer screen at a speed of 30 % of the screen length per second. In the High-Speed Component, the response button moved across the computer screen at a speed of 60 % of the screen length per second. A VI 10 s of point loss (-95) disrupted responding during the test. Behavioral resistance was calculated as proportional changes from baseline response rates to test response rates. When the point-loss disrupted responding, greater resistance was observed in the Low-Speed Component, corroborating previous studies with other dimensions of physical requirements.

Leadership is a risky behaviour that can impact individuals and groups. Leaders, i.e. individuals who perform or initiate a task while other individuals in the group follow, have been studied in different contexts, but there is still a lack of understanding on the role of individual characteristics that may predispose them to become leaders, such as dominance and personality. In particular, the characteristics of leaders in domestic animal populations has been poorly examined. We studied leadership within 32 groups of young pigs (Sus scrofa domesticus, n = 366 individuals). Leadership was assessed during a group-based fear test (Human Approach Test) which was repeated three times. The first individual per group to touch the person was identified as leader. We assessed repeatability of leadership and characteristics of leaders as compared to followers. Leadership was marginally repeatable, with 6 out of 26 groups having a consistent single leader across all tests. Females had odds 4.13 times greater than males of being a leader, while there was no effect of body weight (a proxy of dominance) or coping style on leadership. The results indicate a similarity with wild populations, in which females lead the herd even though the males, which are superior in body weight, are often dominant.

Agonistic behaviors are crucial and ubiquitous among animals for the competition of limited resources. Although the study of aggression has been a popular topic, plenty of studies focused on model organisms, and typically on crayfish and lobsters for crustaceans. Variations of the agonistic behaviors and the underpinning eliciting cues of other crustaceans therefore have not been fully explored. In the present study, we targeted Stenopus, a genus of shrimp-like crustaceans that displays prominent agonistic behaviors when encountering conspecifics of the same sex owing to their monogamous social structure. Using S. hispidus (Olivier, 1811) and S. cyanoscelis (Goy, 1984) as representatives, we characterized their agonistic behaviors and fighting pattern, conducted experiments to investigate the contribution of visual, olfactory and tactile cues to inducing aggression, and examined the effects of antennal and antennular ablation on their agonistic interactions. A total of seven agonistic behaviors were documented, where antennal entwining and tactile contact is the major driver and seemingly important cue, respectively, in inducing agonistic behaviors in Stenopus. Although ablation of antennae and antennules did not inhibit fighting, behavioral changes, such as the prolonged agonistic interactions and the delayed establishment of dominance were observed, suggesting a reduction of aggressiveness. A comparison of agonistic behaviors with other crustaceans showed that certain features appeared to be unique or distinct in Stenopus, including the potential functional overlap of antennae and antennules, a higher aggressiveness of the fighting behaviors, and the exhibition of crouching behavior by submissive individuals. The present study provides a crucial background understanding for subsequent research on Stenopus and paves the way for its establishment as another crustacean model for studying aggression.

Predation pressure influences animal behaviour in relation to feeding, exposure to predators and habitat use. In the presence of a predator, prey usually decreases feeding and activity, avoiding predation-risk areas. This study evaluated the visual effects of a predator fish (red-bellied piranha Pygocentrus nattereri) on the behaviour and habitat use of Macrobrachium jelskii prawn. It was hypothesized that prawns would modify their behaviour in the presence of a predator, decreasing their general activity (foraging and locomotion) and seeking shelter more frequently. Twenty behavioural tests were carried out without and with the presence of a predator using five different M. jelskii individuals per trial. Behavioural data were collected using scan sampling with instantaneous recording of behaviours every 15 s during 5 min in each trial. The presence of the predator caused prawns to decrease their locomotion and feeding and increase environment exploration and predator inspection. Prawns used the shelter more frequently when the predator was present. Red-bellied piranha elicited anti-predator behaviour in M. jelskii. The patterns observed suggested that the most common anti-predatory behaviours exhibited by M. jelskii are beneficial as they reduce vigilance and active anti-predation strategies, such as escape.