Fred C. Dyer

Dance dialects and foraging range in three Asian honey bee species

SummaryWe measured the “distance dialects” in the dance languages of three honey bee species in Thailand (Apis florea, A. cerana, and A. dorsata), and used these dialects to examine the hypothesis that a colonys dialect is adaptively “tuned” to enhance efficiency of communication over the distances that its foragers typically fly. in contrast to previous interspecific comparisons in Sri Lanka (Lindauer 1956; Punchihewa et al. 1985), we found no striking dialect differences among the Asian bees in Thailand. The adaptive tuning hypothesis predicts that the foraging ranges of the three species should also be similar, but comparisons of colonial foraging range using the “forage mapping” technique (Visscher and Seeley 1982) actually revealed marked differences. This raises the possibility that the link between ecology and distance code is more subtle than previously supposed, if a link exists at all.

Predator confusion is sufficient to evolve swarming behaviour

Swarming behaviours in animals have been extensively studied owing to their implications for the evolution of cooperation, social cognition and predator–prey dynamics. An important goal of these studies is discerning which evolutionary pressures favour the formation of swarms. One hypothesis is that swarms arise because the presence of multiple moving prey in swarms causes confusion for attacking predators, but it remains unclear how important this selective force is. Using an evolutionary model of a predator–prey system, we show that predator confusion provides a sufficient selection pressure to evolve swarming behaviour in prey. Furthermore, we demonstrate that the evolutionary effect of predator confusion on prey could in turn exert pressure on the structure of the predators visual field, favouring the frontally oriented, high-resolution visual systems commonly observed in predators that feed on swarming animals. Finally, we provide evidence that when prey evolve swarming in response to predator confusion, there is a change in the shape of the functional response curve describing the predators consumption rate as prey density increases. Thus, we show that a relatively simple perceptual constraint—predator confusion—could have pervasive evolutionary effects on prey behaviour, predator sensory mechanisms and the ecological interactions between predators and prey.

14 – Gaze Control for Face Learning and Recognition by Humans and Machines

In this chapter we describe an ongoing project designed to investigate gaze control in face perception, a problem of central importance in both human and machine vision. The project uses converging evidence from behavioral studies of human observers and computational studies in machine vision. The research is guided by a formal framework for understanding gaze control based on Markov decision processes (MDPs). Behavioral data from human observers provide new insight into gaze control in a complex task, and are used to motivate an artificial gaze control system using the Markov framework. Furthermore, the efficacy of a foveal Markov-based approach to gaze control for face recognition in machine vision is tested. The general goal of the project is to uncover key principles of gaze control that cut across the specific implementation of the system (biological or machine).

Nocturnal orientation by the Asian honey bee, Apis dorsata

Abstract Honey bees have been observed to forage and dance on moonlit nights, but it has never been established whether the moon serves as a reference in orienting nocturnally active bees. The present study, of the Asian honey bee Apis dorsata , suggests that although the moons illumination is essential for nocturnal flight, the moon itself is ignored for orienting the dances. Rather, bees probably use the suns position as a reference point for their dances, even though the sun is below the horizon. This ability may involve an extension of the mechanism that honey bees employ to find the sun on overcast days.

Memory and sun compensation by honey bees

SummaryExperiments with two species of honey bees (Apis mellifera andA. cerana) have revealed that bees form a detailed memory of the spatial and temporal pattern of the suns azimuthal movement, using local landmarks as a reference for the learning. These experiments were performed on overcast days, and consisted of removing a hive from one site in which bees had been trained to find food by flying along a prominent landmark, and displacing it to a similar site in which the landmark was aligned in a different compass direction. On overcast days, bees which flew along the landmark in the new site oriented their waggle dances in the hive as if they had actually flown in the training site. Thus, they confused the two sets of landmarks and set their dance angles according to a memory of the suns position relative to the original landmarks. Furthermore, the dances changed in correspondence with the suns azimuthal shift over several hours, even reflecting (approximately) the regular temporal variations in the rate of shift; such features of the suns course must therefore be stored in memory. The primary mechanism underlying the learning of this pattern is probably similar to that proposed by New and New (1962): bees store in memory several time-linked solar azimuthal positions relative to features of the landscape, and refer to this stored array when they need to determine an unknown azimuth intermediate between two known positions.During the cloudy-day displacement experiments, celestial cues often appeared to bees in the new site, contradicting the stored information on which they had been basing their dances. Although most bees quickly adopted the dance angle reflecting their actual direction of flight relative to the sun, some later reverted to the original dance angle, indicating that the information on which it was based had remained in memory when the new information was being expressed; other bees performed bimodal dances which expressed both sets of information in alternate waggle runs. The separation in memory implied by these behaviors may reflect a neural strategy for updating a previously stored relationship between celestial and terrestrial references with new information presented by seasonal changes in the suns course or by newly learned landmarks.

Mechanisms of dance orientation in the Asian honey beeApis florea L.

SummaryEarly studies of dance communication inApis florea had shown that waggle dances are not performed on a vertical plane and oriented to gravity, as in the other species ofApis, but instead take place on the flattened top of the exposed comb and are oriented to celestial cues directly. More recent experiments showed thatA. florea can dance in the absence of a view of the sun or blue sky, but did not establish what mechanism permitted this orientation. I now report that dances can be oriented directly to landmarks visible from the nest, the first evidence of an environmental feature other than celestial cues or gravity being involved in dance orientation. Landmarks near the nest are probably used to refer to celestial cues, in a fashion analogous to the use of broad features of the landscape by honeybees in order to learn the suns course, which permits them to determine their flight angle on overcast days or at night, and to compensate accurately for solar movement.Apis florea may therefore be able to learn the suns course with respect to two sets of landmarks.In other experiments I have examined the influence of slope onA. floreas dance orientation to visual references. In the first extensive observations of its dances on a vertical plane, I have amply confirmed that this species cannot transpose light and gravity in setting its dance angle, as the other species ofApis can. Nor do dancers orient so as to match visual information seen during the dance with that remembered from the flight. Patterns in the data when the same patch of sky was presented from different angles suggest instead thatA. florea continues to orient to projections of celestial cues onto the horizontal plane even when dancing on a steep slope. This compensation for slope may involve an ability to detect gravity and factor it out in aligning the dance to celestial cues.These insights suggest thatA. floreas dance orientation system has been adapted to requirements imposed by its nesting behavior, and has diverged sharply from the system shared by the other species ofApis.

Face Recognition Using Foveal Vision

Data from human subjects recorded by an eyetracker while they are learning new faces shows a high degree of similarity in saccadic eye movements over a face. Such experiments suggest face recognition can be modeled as a sequential process, with each fixation providing observations using both foveal and parafoveal information. We describe a sequential model of face recognition that is incremental and scalable to large face images. Two approaches to implementing an artificial fovea are described, which transform a constant resolution image into a variable resolution image with acute resolution in the fovea, and an exponential decrease in resolution towards the periphery. For each individual in a database of faces, a hidden-Markov model (HMM) classifier is learned, where the observation sequences necessary to learn the HMMs are generated by fixating on different regions of a face. Detailed experimental results are provided which show the two foveal HMM classifiers outperform a more traditional HMM classifier built by moving a horizontal window from top to bottom on a highly subsampled face image.

5 – Spatial Cognition: Lessons from Central-place Foraging Insects

Publisher Summary This chapter discusses the recent research on spatial orientation insects, with the aim of showing how these animals provide a model for the development of an integrated theory of spatial cognition. Most of the research concerns orientation by hymenopteran insects (bees, wasps, and ants) that have a central nest, and hence face the task of finding their way back repeatedly to a specific point in the environment, sometimes from great distances away (hundreds or even thousands of meters). Some species keep returning repeatedly to rich feeding sites, and may visit several such feeding sites during their lifetimes. To solve these navigational problems, insects typically rely upon visual information about landmarks and celestial cues. This, in turn, entails learning the spatial relationships between these references and locations in the insects natal habitat. Behavioral evidence suggests that these learning processes include mechanisms to manipulate internally represented information to compute spatial relationships that the animal has not directly experienced. Thus, insects offer an opportunity to study, in animals with modest-sized nervous systems, the mechanisms underlying such cognitive capacities. Research on insect navigation provides an example of how the study of spatial cognition could be broadened and made truly integrative.

Plasticity of spatial memory in honey bees: reorientation following colony fission

Abstract Abstract. Honey bees, Apis mellifera , that leave their natal colony with a reproductive swarm are known to establish a new nest within the foraging range of the natal colony. Experiments with natural swarms confirmed that bees rapidly learn to return to their new hive following colony fission, even if the natal hive stands a short distance away. Experiments with artificial swarms demonstrated similar reorientation by bees and further showed that the experience of being in a swarm triggers patterns of behaviour apparently used in reorientation. In addition, bees remembered information about the natal nest even after they moved to a new nest: reoriented bees from artificial swarms deprived of their new hive returned to their natal hive rather than to another equidistantly located hive. These results demonstrate a high degree of plasticity in honey bee spatial memory; experienced foragers returning to their new nest apparently can adopt new responses to landmarks that were previously used to guide them to their natal nest, while still retaining the ability to locate their natal nest.

Exploring the evolution of a trade-off between vigilance and foraging in group-living organisms.

Even though grouping behaviour has been actively studied for over a century, the relative importance of the numerous proposed fitness benefits of grouping remain unclear. We use a digital model of evolving prey under simulated predation to directly explore the evolution of gregarious foraging behaviour according to one such benefit, the ‘many eyes’ hypothesis. According to this hypothesis, collective vigilance allows prey in large groups to detect predators more efficiently by making alarm signals or behavioural cues to each other, thereby allowing individuals within the group to spend more time foraging. Here, we find that collective vigilance is sufficient to select for gregarious foraging behaviour as long there is not a direct cost for grouping (e.g. competition for limited food resources), even when controlling for confounding factors such as the dilution effect. Furthermore, we explore the role of the genetic relatedness and reproductive strategy of the prey and find that highly related groups of prey with a semelparous reproductive strategy are the most likely to evolve gregarious foraging behaviour mediated by the benefit of vigilance. These findings, combined with earlier studies with evolving digital organisms, further sharpen our understanding of the factors favouring grouping behaviour.