Visual Ecology Research Articles

Measuring compound eye optics with microscope and microCT images

With a great variety of shapes and sizes, compound eye morphologies give insight into visual ecology, development, and evolution, and inspire novel engineering. In contrast to our own camera-type eyes, compound eyes reveal their resolution, sensitivity, and field of view externally, provided they have spherical curvature and orthogonal ommatidia. Non-spherical compound eyes with skewed ommatidia require measuring internal structures, such as with MicroCT (µCT). Thus far, there is no efficient tool to characterize compound eye optics, from either 2D or 3D data, automatically. Here we present two open-source programs: (1) the ommatidia detecting algorithm (ODA), which measures ommatidia count and diameter in 2D images, and (2) a µCT pipeline (ODA-3D), which calculates anatomical acuity, sensitivity, and field of view across the eye by applying the ODA to 3D data. We validate these algorithms on images, images of replicas, and µCT eye scans from ants, fruit flies, moths, and a bee.

Визуально-экологический поворот в оценке технической среды

An unprecedented turn is taking place before our eyes: the technical environment, having changed, participates in the substitution of the sphere of the imaginary for the sphere of the technical in the digitalization mode. Images bring us together and hold us, becoming the focus of the essence of the digital and material world. The article outlines the basics of the visual-ecological approach in creating a human-sized digital environment. By giving ourselves to interfaces and their technical requirements, we hope that we have won freedom, time, life. In fact, we can lose everything if the images we create quantitatively express our technological capabilities to a greater extent than qualitatively deepen our own human experience. We find ourselves in a situation similar to the archaic one, when a person, through the rituals and techniques invented by him, tamed his own dreams, his fantasies, and through them himself, pacifying the demons of imagination. Today, technical images are more insatiable than archaic demons because they claim a massive intensification of experience, but at the same time lead to an explosion of the imaginative, to burnout, chronic disinterest, to boredom. We produce images better than we know how to inhabit them. We have industrial technologies for their creation, but there are no body techniques adequate to their living. Theory should change its approach to technical images: think not about them, but together with them, about those techniques of the body and the worlds that they discover, about the criteria and requirements that they set, about where they direct our desires and where they inspire our dreams. It is assumed that, in order to understand the potential of visual ecology, one should take into account a number of methods related to the interpretation of bodily experience: (1) the method of topological reflection. The digital image apparently removes one of the fundamental interactions of the Universe -gravitational. We cannot resist the attraction of the digital image until we recreate it for understanding at the conceptual level, until we recreate the context and connect the growth of digital suggestion with the possibilities of the environment; (2) the method of somatic epistemology. The body is a graveyard of signs, it bears meta processes from which it is already culturally and technically excluded, but they continue to work, they constitute the cultural archive of the body, and new technologies do not specifically respond to practical intentions, but to the actualization of archived experience, which suddenly becomes important in a new environment; (3) the method of empirical constructivism: thinking through the evolutionary conditions of digital objects, the principle of their construction from information data in the world of algorithms and glitches, taking into account the peculiarities of human experience.

Retinal Ganglion Cell Topography and Spatial Resolution in Three Indian Pteropodid Bats

Pteropodidae is the only phytophagous bat family that predominantly depends on visual and olfactory cues for orientation and foraging. During daytime, pteropodids of different species roost in sites with varying light exposure. Pteropodids have larger eyes relative to body size than insectivorous bats. Retinal topography has been studied in less than 10% of the approximately 200 pteropodid species, a behavioural estimation of spatial resolution is available only for Pteropus giganteus, and little is known about the relationship between their roost site preference and visual ecology. We present retinal ganglion cell topographic maps and anatomical estimates of spatial resolution in three southern Indian pteropodid species with different roosting preferences. Ganglion cell densities are between 1,000 and 2,000 cells/mm² in the central retina and lower in the dorsal and ventral periphery. All three species have a temporal area in the retina with peak ganglion cell densities of 4,600–6,600 cells/mm². As a result, the foliage-roosting Cynopterus sphinx and the cave-roosting Rousettus leschenaultii have similar anatomical resolution (2.7 and 2.8 cycles/degree, respectively). The anatomical estimate for the larger tree-roosting P. giganteus (4.0 cycles/degree) is higher than the spatial resolution determined earlier in behavioural tests. Like other pteropodids and unlike other vertebrates, all three species have choroidal papillae. Based on 15 pteropodid species studied to date, we find no relationship between roost type and eye size or visual acuity. For a general understanding of the sensory ecology of pteropodids that perform key ecosystem services in the tropics, it will be essential to study additional species.

FORMATION OF FACADES THROUGH THE PRISM OF VISUAL ECOLOGY

Modernity is characterized by very rapid changes in the environment in which a person lives. The human body has evolved to adapt to the natural environment for thousands of years, and to living in an urban environment relatively recently. Therefore, the urban influence is "aggressive" for the human psyche, as it differs significantly from the natural conditions of habitation. The article attempts to analyze the peculiarities of the formation of building facades through the prism of human emotions and similarity to the natural environment. This made it possible to identify the main trends and methods of forming the facades of residential and public buildings that have developed in recent decades. Recently, scientists of various fields have been actively studying the issue of human psychological health, which is largely formed by a certain emotional influence of the external environment and enters (80%) through the visual channel. Constant visual perception of the environment (especially urban), its saturation with visual elements has a significant impact on the psychological state of a person. The article examines the characteristics of homogeneous and aggressive fields in urban architecture and methods of their elimination. The traditional vertical division of the facade into 3 parts (1-2 floor "lower tier", the following floors until completion "middle tier" and "upper tier" itself is considered), design of the entrance, windows and summer rooms. The basic requirements for the architectural solution of each tier and the elements that fill it are formulated. Attention was paid to the recommendations of specialists in visual ecology and the basic requirements for the formation of facades of residential and public facilities were formulated, which will allow creating a comfortable environment for residents of cities and towns.

Characterization of visual response properties and connectivity of Wide-field vertical neurons in the mouse superior colliculus

Vision is a sense that serves different ethological functions across species. Visual information can be used to either detect preys or predators and generate orienting or escaping responses. The superior colliculus has been implicated in the orchestration of these behaviors. Within this structure, at the interface between the visual and the multisensory layers, lay the wide-field vertical neurons (WFV). WFV are a conserved morphologically defined cell-type found across many taxa from reptiles to highly visual mammals, independently of their visual ecology. In mammals, these neurons receive direct inputs from the retina and the primary visual cortex, and have the pulvinar as a known target, however, their brain-wide connectivity remains to be identified. These cells display peculiar response properties, but despite their ubiquity and unique morphology, their contribution to vision remains elusive. In this study, we have characterized WFV morphology, connection, and visual response properties in vivo in the laboratory mouse. Viral intersectional approaches revealed their projection patterns. Two-photon calcium imaging in awake mice using a transgenic Cre-line targeting specifically WFV (NTSR1-Cre) confirmed their unique response properties. WFV showed a strong preference for small moving stimuli and a slight bias for certain directions. Interestingly, visual responses to distinct visual stimuli showed variable degrees of adaptation upon repeated presentation. In addition, Cre-dependent rabies tracing unraveled a variety of sources of input which had not been described previously. These results place WFV as a major integrator of visual information in the superior colliculus. Their adaptation to looming stimulus suggest a role in ethologically relevant function in avoiding inappropriate responses, while sustained responses to small moving stimulus might be linked to attentional processes and orienting behaviors. Taken together, this initial characterization paves the way to elucidate the role of these neurons in visual behavior.

Using colour pattern edge contrast statistics to predict detection speed and success in triggerfish (Rhinecanthus aculeatus).

Edge detection is important for object detection and recognition. However, we do not know whether edge statistics accurately predict the detection of prey by potential predators. This is crucial given the growing availability of image analyses and their application across non-human visual systems. Here, we investigated whether Boundary Strength Analysis (BSA), Local Edge Intensity Analysis (LEIA) and the Gabor Ratio (GabRat) could predict the speed and success with which triggerfish (Rhinecanthus aculeatus) detected patterned circular stimuli against a noisy visual background, in both chromatic and achromatic presentations. We found various statistically significant correlations between edge statistics and detection speed depending on treatment and viewing distance; however, individual pattern statistics only explained up to 2% of the variation in detection time, and up to 6% when considering edge statistics simultaneously. We also found changes in fish response over time. While highlighting the importance of spatial acuity and relevant viewing distances in the study of visual signals, our results demonstrate the importance of considering explained variation when interpreting colour pattern statistics in behavioural experiments. We emphasize the need for statistical approaches suitable for investigating task-specific predictive relationships and ecological effects when considering animal behaviour. This is particularly important given the ever-increasing dimensionality and size of datasets in the field of visual ecology.

Parallel evolution of opsin visual pigments in hawkmoths by tuning of spectral sensitivities during transition from a nocturnal to a diurnal ecology.

Light environments differ dramatically between day and night. The transition between diurnal and nocturnal visual ecology has happened repeatedly throughout evolution in many species. However, the molecular mechanism underlying the evolution of vision in recent diurnal-nocturnal transition is poorly understood. Here, we focus on hawkmoths (Lepidoptera: Sphingidae) to address this question by investigating five nocturnal and five diurnal species. We performed RNA-sequencing analysis and identified opsin genes corresponding to the ultraviolet (UV), short-wavelength (SW) and long-wavelength (LW)-absorbing visual pigments. We found no significant differences in the expression patterns of opsin genes between the nocturnal and diurnal species. We then constructed the phylogenetic trees of hawkmoth species and opsins. The diurnal lineages had emerged at least three times from the nocturnal ancestors. The evolutionary rates of amino acid substitutions in the three opsins differed between the nocturnal and diurnal species. We found an excess number of parallel amino acid substitutions in the opsins in three independent diurnal lineages. The numbers were significantly more than those inferred from neutral evolution, suggesting that positive selection acted on these parallel substitutions. Moreover, we predicted the visual pigment absorption spectra based on electrophysiologically determined spectral sensitivity in two nocturnal and two diurnal species belonging to different clades. In the diurnal species, the LW pigments shift 10 nm towards shorter wavelengths, and the SW pigments shift 10 nm in the opposite direction. Taken together, our results suggest that parallel evolution of opsins may have enhanced the colour discrimination properties of diurnal hawkmoths in ambient light.

Artificial light at night correlates with seabird groundings: mapping city lights near a seabird breeding hotspot.

Artificial light at night (ALAN) is a growing conservation concern for seabirds, which can become disoriented and grounded by lights from buildings, bridges and boats. Many fledgling seabirds, especially Procellariiformes such as petrels and shearwaters, are susceptible to light pollution. The Hauraki Gulf, a seabird hotspot located near Tāmaki Makaurau/Auckland, Aotearoa—New Zealand’s largest urban city, with a considerable amount of light pollution and regularly documented events of seabird groundings. We aim to identify the characteristics of locations especially prone to seabird groundings. We used an online database of seabirds taken to a wildlife rescue facility by the public to map 3 years of seabird groundings and test for correlations between seabird groundings and the natural night sky brightness. We found that areas with lower amounts of natural night sky brightness and greater light pollution often had a higher number of seabirds grounded. Further, we identified important seasonal patterns and species differences in groundings. Such differences may be a by-product of species ecology, visual ecology and breeding locations, all of which may influence attraction to lights. In general, seabird groundings correlate with the brightness of the area and are species-specific. Groundings may not be indicative of human or seabird population abundance considering some areas have a lower human population with high light levels and had high amounts of seabird groundings. These findings can be applied worldwide to mitigate groundings by searching and targeting specific brightly lit anthropogenic structures. Those targeted structures and areas can then be the focus of light mitigation efforts to reduce seabird groundings. Finally, this study illustrates how a combination of community science, and a concern for seabirds grounded from light attraction, in addition to detailed animal welfare data and natural night sky brightness data can be a powerful, collaborative tool to aid global conservation efforts for highly-at-risk animals such as seabirds.

Low-level Eschatology: Ruins in Computer Games

The ruins are a well-studied object in the history of culture. The article examines the ruins not only in terms of established approaches, but also from the perspective of media theory, visual ecology and game studies, new humanities oriented on exploring digital experience. Ruins in computer games, continuing the tradition of artificial ruins in European history, load the digital space with meaning, metaphysics, memory, stitch game and non-game contexts together and become a medium in its purest form — an intermediary that leads the gamer to the fragments of his identity, to the ruins of his inner experience. Digital ruins, fragmentary and partial in nature, reveal to us the pleasure of fragmentation and deconstruction that precede the new assemblage of reality. The article deals in addition with digital catastrophism, eschatology and ruinization in 11 bit studios games — This War of Mine (2014) and Frostpunk (2018).

Towards Visual Ecology of Digital City

Contemporary city is a digital city. It is real and the techniques of its living are no poorer than the techniques of developing pre-digital cities. The city of the digital age does not dissolve into virtuality but, on the contrary, acquires new levels and dimensions. It is expanding, as is the range of the models managing it, which are formed on the basis of new technologies. The city is turning into a complex mechanism that produces and processes data flows. Architecture, urban management, and practices of citizens are increasingly basing on digital technologies. In the article, the authors set the context of the thematic issue through the introduction of two registers of visuality of contemporary city: a visible city that changes under the influence of the digital, and an invisible city created by algorithms.

“Slow” Visual Environment in the Urban Landscapes

The article observes different aspects of the visual ecology in the urban architectural environment and a new public discussion that arose around the anti-acceleration trends (“Slow Architecture”, “Slow Cities”). The theory of the urbanized landscapes visual image’s perception analyzes, from the standpoint of rational aesthetics, critical theory of architecture, topological reflection, and the new ethics of consumption. Philosophical reflection on the phenomenon of slow perception of life, slow activity and the meaning of contemplation is of great importance for the formation of the concept of “slow visual environment”. The hypothesis of the need to limit the iconic forms’ entropy in the visual environment is verified by the examples of objects creating an aggressive landscape and visual pollution. Criteria are offered, defining the visual pollution of urban landscapes, as well as the methods for achieving visual environmental friendliness by slowing down the visual message.

Adaptive optics in the Arctic? A commentary on Fosbury and Jeffery.

Adaptive optics in the Arctic? A commentary on Fosbury and Jeffery.

In the field: an interview with Sönke Johnsen

Sönke Johnsen is a Professor at Duke University, USA, investigating visual ecology. After completing his degree in mathematics at Swarthmore College, USA, and a PhD with William Kier at University of North Carolina at Chapel Hill, USA, Johnsen worked as a post-doc with Edie Widder at Harbor Branch Oceanographic Institution, USA, and Larry Madin at Woods Hole Oceanographic Institution, USA. He remained at Woods Hole as an Assistant Scientist before moving to Duke as an Assistant Professor. Johnsen talks about his experiences of collecting transparent animals while blue water diving and in a submersible, as well as outrunning Hurricane Katrina in 2005.

Study of Visual Garbage as Visual Ecology Perspective

The following article explores the notion of visual garbage and considers various strategies for its recycling, upcycling, and use. Visual garbage is investigated in the context of media sphere development and the theory of garbage itself. The authors propose to analyse such approaches of visual garbage use, as visual camouflage and glitch art, as well as to examine the principles of visual garbage recycling in terms of the Aristotelian conception of causality. Understanding garbage as a medium helps not only to uncover the features of its circulation, but also to consider garbage as a source of knowledge accumulation. Moreover, it helps to find new social, political and aesthetic strategies for understanding contemporaneity, which in turn allows us to draw conclusions about the untapped potential of visual garbage. Visual garbage not only becomes a source of visual pollution, but also contains a resource for reality conversion. In order to determine the criteria for visual pollution, it is necessary to examine the performative productivity of garbage and its effect as a mediating tool.

Ancient whale rhodopsin reconstructs dim-light vision over a major evolutionary transition: Implications for ancestral diving behavior

Cetaceans are fully aquatic mammals that descended from terrestrial ancestors, an iconic evolutionary transition characterized by adaptations for underwater foraging via breath-hold diving. Although the evolutionary history of this specialized behavior is challenging to reconstruct, coevolving sensory systems may offer valuable clues. The dim-light visual pigment, rhodopsin, which initiates phototransduction in the rod photoreceptors of the eye, has provided insight into the visual ecology of depth in several aquatic vertebrate lineages. Here, we use ancestral sequence reconstruction and protein resurrection experiments to quantify light-activation metrics in rhodopsin pigments from ancestors bracketing the cetacean terrestrial-to-aquatic transition. By comparing multiple reconstruction methods on a broadly sampled cetartiodactyl species tree, we generated highly robust ancestral sequence estimates. Our experimental results provide direct support for a blue-shift in spectral sensitivity along the branch separating cetaceans from terrestrial relatives. This blue-shift was 14 nm, resulting in a deep-sea signature (λmax = 486 nm) similar to many mesopelagic-dwelling fish. We also discovered that the decay rates of light-activated rhodopsin increased in ancestral cetaceans, which may indicate an accelerated dark adaptation response typical of deeper-diving mammals. Because slow decay rates are thought to help sequester cytotoxic photoproducts, this surprising result could reflect an ecological trade-off between rod photoprotection and dark adaptation. Taken together, these ancestral shifts in rhodopsin function suggest that some of the first fully aquatic cetaceans could dive into the mesopelagic zone (>200 m). Moreover, our reconstructions indicate that this behavior arose before the divergence of toothed and baleen whales.

Chimpanzee (Pan troglodytes) gaze is conspicuous at ecologically-relevant distances

Chimpanzee (Pan troglodytes) sclera appear much darker than the white sclera of human eyes, to such a degree that the direction of chimpanzee gaze may be concealed from conspecifics. Recent debate surrounding this topic has produced mixed results, with some evidence suggesting that (1) primate gaze is indeed concealed from their conspecifics, and (2) gaze colouration is among the suite of traits that distinguish uniquely social and cooperative humans from other primates (the cooperative eye hypothesis). Using a visual modelling approach that properly accounts for specific-specific vision, we reexamined this topic to estimate the extent to which chimpanzee eye coloration is discriminable. We photographed the faces of captive chimpanzees and quantified the discriminability of their pupil, iris, sclera, and surrounding skin. We considered biases of cameras, lighting conditions, and commercial photography software along with primate visual acuity, colour sensitivity, and discrimination ability. Our visual modeling of chimpanzee eye coloration suggests that chimpanzee gaze is visible to conspecifics at a range of distances (within approximately 10 m) appropriate for many species-typical behaviours. We also found that chimpanzee gaze is discriminable to the visual system of primates that chimpanzees prey upon, Colobus monkeys. Chimpanzee sclera colour does not effectively conceal gaze, and we discuss this result with regard to the cooperative eye hypothesis, the evolution of primate eye colouration, and methodological best practices for future primate visual ecology research.

Enhanced short-wavelength sensitivity in the blue-tongued skink Tiliqua rugosa.

ABSTRACTDespite lizards using a wide range of colour signals, the limited variation in photoreceptor spectral sensitivities across lizards suggests only weak selection for species-specific, spectral tuning of photoreceptors. Some species, however, have enhanced short-wavelength sensitivity, which probably helps with the detection of signals rich in ultraviolet and short wavelengths. In this study, we examined the visual system of Tiliqua rugosa, which has an ultraviolet/blue tongue, to gain insight into this species' visual ecology. We used electroretinograms, opsin sequencing and immunohistochemical labelling to characterize whole-eye spectral sensitivity and the elements that shape it. Our findings reveal that T. rugosa expresses all five opsins typically found in lizards (SWS1, SWS2, RH1, RH2 and LWS) but possesses greatly enhanced short-wavelength sensitivity compared with other diurnal lizards. This enhanced short-wavelength sensitivity is characterized by a broadening of the spectral sensitivity curve of the eye towards shorter wavelengths while the peak sensitivity of the eye at longer wavelengths (560 nm) remains similar to that of other diurnal lizards. While an increased abundance of SWS1 photoreceptors is thought to mediate elevated ultraviolet sensitivity in a couple of other lizard species, SWS1 photoreceptor abundance remains low in this species. Instead, our findings suggest that short-wavelength sensitivity is driven by multiple factors which include a potentially red-shifted SWS1 photoreceptor and the absence of short-wavelength-absorbing oil droplets. Examining the coincidence of enhanced short-wavelength sensitivity with blue tongues among lizards of this genus will provide further insight into the co-evolution of conspecific signals and whole-eye spectral sensitivity.

Chemical and visual ecology of the Symphyta

Abstract The Symphyta is the most basal sub‐order of the Hymenoptera and includes the woodwasps, horntails and sawflies, many of which are pests. Adults are generally short‐lived and as a result males and females experience strong selection to rapidly find a mate and females to find oviposition sites. Mate‐searching typically relies on visual and olfactory stimuli such as sexually dimorphic morphology (i.e., body parts used in signalling) and pheromones. Here we review the available literature on the chemical and visual ecology of the Symphyta with potential for use in survey and detection programmes. Stimuli reviewed include but are not limited to sex pheromones, larval defensive compounds, plant kairomones and colour preferences. Sex pheromones are known for 19 species of Symphyta and show shared evolutionary patterns in chemistry, production site and ecological role. In general, sex pheromones in the Symphyta are female‐produced, oxidized cuticular hydrocarbons and yellow traps capture more individuals than other colours, although exceptions do exist. More work is needed to expand on these and identify new patterns in the visual and chemical ecology of the Symphyta.

Animal Coloration in the Anthropocene

Natural habitats are increasingly affected by anthropogenically driven environmental changes resulting from habitat destruction, chemical and light pollution, and climate change. Organisms inhabiting such habitats are faced with novel disturbances that can alter their modes of signaling. Coloration is one such sensory modality whose production, perception and function is being affected by human-induced disturbances. Animals that acquire pigment derivatives through diet are adversely impacted by the introduction of chemical pollutants into their environments as well as by general loss of natural habitat due to urbanization or logging leading to declines in pigment sources. Those species that do manage to produce color-based signals and displays may face disruptions to their signaling medium in the form of light pollution and turbidity. Furthermore, forest fragmentation and the resulting breaks in canopy cover can expose animals to predation due to the influx of light into previously dark environments. Global climate warming has been decreasing snow cover in arctic regions, causing birds and mammals that undergo seasonal molts to appear conspicuous against a snowless background. Ectotherms that rely on color for thermoregulation are under pressure to change their appearances. Rapid changes in habitat type through severe fire events or coral bleaching also challenge animals to match their backgrounds. Through this review, we aim to describe the wide-ranging impacts of anthropogenic environmental changes on visual ecology and suggest directions for the use of coloration both as an indicator of ecological change and as a tool for conservation.

CamoEvo: An open access toolbox for artificial camouflage evolution experiments.

Camouflage research has long shaped our understanding of evolution by natural selection, and elucidating the mechanisms by which camouflage operates remains a key question in visual ecology. However, the vast diversity of color patterns found in animals and their backgrounds, combined with the scope for complex interactions with receiver vision, presents a fundamental challenge for investigating optimal camouflage strategies. Genetic algorithms (GAs) have provided a potential method for accounting for these interactions, but with limited accessibility. Here, we present CamoEvo, an open‐access toolbox for investigating camouflage pattern optimization by using tailored GAs, animal and egg maculation theory, and artificial predation experiments. This system allows for camouflage evolution within the span of just 10–30 generations (∼1–2 min per generation), producing patterns that are both significantly harder to detect and that are optimized to their background. CamoEvo was built in ImageJ to allow for integration with an array of existing open access camouflage analysis tools. We provide guides for editing and adjusting the predation experiment and GA as well as an example experiment. The speed and flexibility of this toolbox makes it adaptable for a wide range of computer‐based phenotype optimization experiments.