Immersive virtual reality for learning about ecosystems: effect of two signaling levels and feedback on action decisions.

Introduction: The goal of the present study was to test the effect of signaling associated with feed-back in learning forest ecosystems in the context of realistic living forest simulator, in IVR conditions for students in agriculture. Two signaling modalities, corresponding to two signaling levels, were investigated: visual flashing of forest elements (tree species, plants, flowers, fungi, wet-areas etc.) and marker-stones, both with text in pop-up windows, in a 2x2 experimental plan. Methods: Ninety-three pupils of an agricultural technological high school had to explore (including physically), interrogate (search for) and select (using the joysticks) relevant elements of the forest in three living forest areas (visually delimited inside of a broader forest area) in order to choose (and justify) the best area, among the three, in which an equipped public-tourist reception site (picnic, resting, reception site) could be built. The chosen site must have the least possible negative impact on the ecosystem of the forest and its development over time. After their decision (and justification) they were provided a feed-back with a series of VR desktop multimedia slides showing the effect of this choice on the ecosystem of the chosen area. After the feed-back they had to decide and justify again whether they would change or maintain their first decision. Finally, subjective scales were also used in order to investigate presence, cognitive complexity, sickness and overall enjoyment. Results and discussion: Results showed significant positive effects of both signaling levels, and of the feed-back on the correct decision answers. Further, the combination, and interaction, between signaling and feedback seemed to enhance, the activation and retrieval from memory, of the task-relevant concepts. In addition, the results indicated a significant positive effect (medium size) of presence on decision performances, a finding which is consistent with the immersion principle.

The effect of biofluorescence on predation upon Cope's gray treefrog: A clay model experiment.

Biofluorescence, the ability to absorb light and reemit it at a longer wavelength, is present in many taxa but has been examined only recently in amphibians. Over half of the studies documenting biofluorescence in the last century suggest this fluorescent signal may affect predation; however, to date, only one other experimental study has tested this hypothesis. To address this question, we experimentally tested the effect of biofluorescence on predation through the study of the Cope's Gray Treefrog, Hyla chrysoscelis. First, we quantified the spectral characteristics of a novel biofluorescence pattern in H. chrysoscelis. In both sexes of this species, the fluorescent signal is concentrated in an area that contains a proposed aposematic pattern to warn predators of the frog's toxic secretions. We hypothesized that the biofluorescent trait may increase the conspicuousness of this pattern and enable the frogs to deter predators more effectively. Second, we tested this prediction by conducting a clay model field experiment to assess differences in predation attempts on fluorescent versus non-fluorescent H. chrysoscelis models by various predator types. We found no effect of biofluorescence on the overall presence, type, or location of predation, suggesting that biofluorescence alone does not act as an antipredator signal of H. chrysoscelis. This study represents one of the first attempts to experimentally test the effect of biofluorescence on predation in any organism and the first to do so in amphibians. Further work is needed to explore the role of this trait in predation in other systems and to investigate alternative functions for the biofluorescent signal in H. chrysoscelis.

Sex-, age-, and time-specific visual communication in brown bears.

Intraspecific communication in mammals is well-documented but generally restricted to chemical and acoustic signaling. However, other overlooked channels, such as visual signaling, may be used to communicate among conspecifics. Here, by using experimental manipulations together with camera traps on 13 brown bear (Ursus arctos) rubbing trees in the Cantabrian Mountains (northwestern Spain), we document detailed temporal patterns and behavioral aspects of a recently discovered novel communication channel for this species, visual signaling through the trunk debarking of focal trees. Video footage showed that visual marking is a sex-, age-, and time-specific means of communication in brown bears, being performed exclusively by adult males during the mating season (mainly April-June in the study area). Trunk debarking was always associated with chemical marking and was never an isolated behavior, suggesting that visual and chemical signals might be complementary. Visual and chemical marks may provide different information; for example, visual marks could be an indicator of individual size and, thus, the dominance status of adult males looking for mating opportunities. This is the first time that evidence is provided showing that visual signaling in a large carnivore is exclusive to a specific class of individuals (adult males) and linked to reproductive needs only. Bear visual signaling not only represents an advance in our comprehension of animal communication but may also serve to easily locate the mating areas of mammals, which are crucial for large carnivore species, such as the brown bear, that frequently need specific and urgent plans for conservation and management.

La comunicación intraespecífica en los mamíferos está bien documentada, pero generalmente se limita a la señalización química y acústica. Sin embargo, otros canales ignorados, como la señalización visual, pueden ser utilizados para comunicarse entre conespecíficos. Aquí, utilizando manipulaciones experimentales junto con cámaras trampa en trece árboles de marcaje de oso pardo Ursus arctos en la Cordillera Cantábrica (noroeste de España), documentamos patrones temporales detallados y aspectos conductuales de un nuevo canal de comunicación recientemente descubierto para esta especie, es decir, la señalización visual a través del descortezado del tronco de árboles focales. Las imágenes de vídeo mostraron que el marcado visual es un medio de comunicación específico de sexo, edad y tiempo en los osos pardos, siendo realizado exclusivamente por los machos adultos durante la época de celo (principalmente entre abril y junio en el área de estudio). El descortezado del tronco siempre estuvo asociado al marcaje químico, y nunca fue un comportamiento aislado, lo que sugiere que las señales visuales y químicas podrían ser complementarias. Las marcas visuales pueden proporcionar una información diferente a las químicas, como por ejemplo el tamaño del individuo y, por tanto, el estatus de dominancia de los machos adultos en busca de oportunidades de apareamiento. Es la primera vez que se aportan pruebas que demuestran que la señalización visual en un gran carnívoro es exclusiva de una clase específica de individuos (los machos adultos) y está vinculada únicamente a las necesidades reproductivas. La señalización visual de los osos no sólo representa un avance en nuestra comprensión de la comunicación animal, sino que también puede servir para localizar fácilmente las zonas de celo de los mamíferos, lo cual es crucial para las especies de grandes carnívoros, como el oso pardo, que con frecuencia necesitan planes específicos y urgentes de conservación y gestión.

Electrochemical/visual microfluidic detection with a covalent organic framework supported platinum nanozyme-based device for early diagnosis of pheochromocytoma.

The development of smart, portable, and sensitive devices for the monitoring of circulating tumor cells (CTCs) is essential to diagnose several diseases, including pheochromocytoma (PCC). Therefore, in this study, a dual-mode (electrochemical/visual) microfluidic device was designed for the rapid and sensitive detection of PCC-CTCs using a microfluidic chip for automatic cell sampling and detection and a smartphone-based three-dimensional-printed accessory for signal output analysis. The device was employed to capture and identify PCC-CTCs via specific immunogenic binding to the norepinephrine transporter and somatostatin receptor, which are overexpressed on the surface of PCC cells. Specifically, targeted-modified magnetic particles were used to capture and separate PCC-CTCs from peripheral blood; then, similarly modified covalent organic framework based nanozymes (COF@Pt) were used as peroxidase mimics to amplify the electrochemical response from H2O2 reduction and catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine by hydroxyl radicals in the presence of the PCC cells to enable visual quantification. Using the prepared microfluidic device, a low detection limit of 1 cell mL-1 at a signal-to-noise ratio of 3 and a wide linear range of 2 to 105 cells mL-1 were achieved. Overall, this work demonstrates a portable, sensitive, and visual platform for PCC diagnostics that meets the requirement for quick and precise point-of-care diagnostics.

The jumping spider Saitis barbipes lacks a red photoreceptor to see its own sexually dimorphic red coloration.

Examining the role of color in mate choice without testing what colors the study animal is capable of seeing can lead to ill-posed hypotheses and erroneous conclusions. Here, we test the seemingly reasonable assumption that the sexually dimorphic red coloration of the male jumping spider Saitis barbipes is distinguishable, by females, from adjacent black color patches. Using microspectrophotometry, we find clear evidence for photoreceptor classes with maximal sensitivity in the UV (359 nm) and green (526 nm), inconclusive evidence for a photoreceptor maximally sensitive in the blue (451 nm), and no evidence for a red photoreceptor. No colored filters within the lens or retina could be found to shift green sensitivity to red. To quantify and visualize whether females may nevertheless be capable of discriminating red from black color patches, we take multispectral images of males and calculate photoreceptor excitations and color contrasts between color patches. Red patches would be, at best, barely discriminable from black, and not discriminable from a low-luminance green. Some color patches that appear achromatic to human eyes, such as beige and white, strongly absorb UV wavelengths and would appear as brighter "spider-greens" to S. barbipes than the red color patches. Unexpectedly, we discover an iridescent UV patch that contrasts strongly with the UV-absorbing surfaces dominating the rest of the spider. We propose that red and black coloration may serve identical purposes in sexual signaling, functioning to generate strong achromatic contrast with the visual background. The potential functional significance of red coloration outside of sexual signaling is discussed.

Visual Signaling in the Semi-Fossorial Lizard Pholidobolus montium (Gymnophthalmidae).

It has been suggested that gymnophthalmids, like most semi-fossorial lacertoids, rely more in chemical cues to communicate, in comparison to other groups, like Iguanids, on which communication is mostly based on visual signaling. We present the first description of visual signaling in the Andean lizard Pholidobolusmontium (Gymnophthalmidae) and a complete ethogram based on ex situ observations (34 different types of behaviors including positions and simple movements). Through the design of conspecific stimulus experiments, we were able to recognize leg-waving as a visual signal, as it is only displayed in presence of conspecifics or in presence of a mirror and was one of first and most frequent displays in this context. We also detected other visual displays like neck-arching and tail-undulation which may also be relevant as visual signals. Based on our results, we propose that visual signaling is also possible in semi-fossorial lizards; however, further studies regarding chemical signal recognition and color detection are required to confirm our hypothesis.

Bioluminescent backlighting illuminates the complex visual signals of a social squid in the deep sea.

Visual signals rapidly relay information, facilitating behaviors and ecological interactions that shape ecosystems. However, most known signaling systems can be restricted by low light levels-a pervasive condition in the deep ocean, the largest inhabitable space on the planet. Resident visually cued animals have therefore been hypothesized to have simple signals with limited information-carrying capacity. We used cameras mounted on remotely operated vehicles to study the behavior of the Humboldt squid, Dosidicus gigas, in its natural deep-sea habitat. We show that specific pigmentation patterns from its diverse repertoire are selectively displayed during foraging and in social scenarios, and we investigate how these behaviors may be used syntactically for communication. We additionally identify the probable mechanism by which D. gigas, and related squids, illuminate these patterns to create visual signals that can be readily perceived in the deep, dark ocean. Numerous small subcutaneous (s.c.) photophores (bioluminescent organs) embedded throughout the muscle tissue make the entire body glow, thereby backlighting the pigmentation patterns. Equipped with a mechanism by which complex information can be rapidly relayed through a visual pathway under low-light conditions, our data suggest that the visual signals displayed by D. gigas could share design features with advanced forms of animal communication. Visual signaling by deep-living cephalopods will likely be critical in understanding how, and how much, information can be shared in one of the planet's most challenging environments for visual communication.

Ultraviolet reflectance and pattern properties in leopard geckos (Eublepharis macularius).

Complex visual signaling through various combinations of colors and patterns has been well documented in a number of diurnal reptiles. However, there are many nocturnal species with highly sensitive vision, being able to discriminate colors in night conditions, as was shown in geckos. Because of their sensitivity to chromatic signals, including UV (ultraviolet), they may have potential hidden features in their coloration, which may play role in intraspecific communication (e.g. mate choice) or interspecific signals (e.g. antipredatory function). We explored this hypothesis in nocturnal Leopard geckos (Eublepharis macularius), a species using visual signals in both antipredation defense and courtship, having ontogenetic color change accompanied by a shift in behavior. We used UV photography and visual modeling in order to compare various aspects of their coloration (luminance, contrast, color proportions) between sexes, age groups and populations. We found that Leopard geckos have considerable UV reflectance in white patches on their tails (and on the head in juveniles). Though, no prominent differences were detected in their coloration between various groups. We hypothesize that the limitation of UV reflectance to the head and tail, which are both actively displayed during defense, especially in juveniles, might potentially boost the effect of antipredation signaling.

Visual and acoustic components of courtship in the bird-of-paradise genus Astrapia (Aves: Paradisaeidae).

The distinctive and divergent courtship phenotypes of the birds-of-paradise make them an important group for gaining insights into the evolution of sexually selected phenotypic evolution. The genus Astrapia includes five long-tailed species that inhabit New Guinea's montane forests. The visual and acoustic components of courtship among Astrapia species are very poorly known. In this study, we use audiovisual data from a natural history collection of animal behavior to fill gaps in knowledge about the visual and acoustic components of Astrapia courtship. We report seven distinct male behaviors and two female specific behaviors along with distinct vocalizations and wing-produced sonations for all five species. These results provide the most complete assessment of courtship in the genus Astrapia to date and provide a valuable baseline for future research, including comparative and evolutionary studies among these and other bird-of-paradise species.

Light matters: testing the "Light Environment Hypothesis" under intra- and interspecific contexts.

The "Light Environment Hypothesis" (LEH) proposes that evolution of interspecific variation in plumage color is driven by variation in light environments across habitats. If ambient light has the potential to drive interspecific variation, a similar influence should be expected for intraspecific recognition, as color signals are an adaptive response to the change in ambient light levels in different habitats. Using spectrometry, avian-appropriate models of vision, and phylogenetic comparative methods, I quantified dichromatism and tested the LEH in both intra- and interspecific contexts in 33 Amazonian species from the infraorder Furnariides living in environments with different light levels. Although these birds are sexually monochromatic to humans, 81.8% of the species had at least one dichromatic patch in their plumage, mostly from dorsal areas, which provides evidence for a role for dichromatism in sex recognition. Furthermore, birds from habitats with high levels of ambient light had higher dichromatism levels, as well as brighter, more saturated, and more diverse plumages, suggesting that visual communication is less constrained in these habitats. Overall, my results provide support for the LEH and suggest that ambient light plays a major role in the evolution of color signals in this group of birds in both intra- and interspecific contexts. Additionally, plumage variation across light environments for these drab birds highlights the importance of considering ambient light and avian-appropriate models of vision when studying the evolution of color signals in birds.

Intrasexual competition underlies sexual selection on male breeding coloration in the orangethroat darter, Etheostoma spectabile.

Elaborate, sexually dimorphic traits are widely thought to evolve under sexual selection through female preference, male-male competition, or both. The orangethroat darter (Etheostoma spectabile) is a sexually dichromatic fish in which females exhibit no preferences for male size or coloration. We tested whether these traits affect individual reproductive success in E. spectabile when multiple males are allowed to freely compete for a female. The quality and quantity of male coloration were associated with greater success in maintaining access to the female and in spawning as the primary male (first male to participate). On the other hand, sneaking behavior showed little correlation with coloration. Male breeding coloration in E. spectabile may therefore demonstrate how intrasexual competition can be a predominant factor underlying the evolution of male ornaments.