Showing papers by "John A. Endler published in 2022"
TL;DR: In this paper , a working hypothesis for deimatic behaviour is proposed, and the available evidence for the evolution, ontogeny, causation, and survival value of deimal behaviour using Tinbergen's Four Questions as a framework.
Abstract: Deimatic behaviours, also referred to as startle behaviours, are used against predators and rivals. Although many are spectacular, their proximate and ultimate causes remain unclear. In this review we aim to synthesise what is known about deimatic behaviour and identify knowledge gaps. We propose a working hypothesis for deimatic behaviour, and discuss the available evidence for the evolution, ontogeny, causation, and survival value of deimatic behaviour using Tinbergen's Four Questions as a framework. Our overarching aim is to direct future research by suggesting ways to address the most pressing questions in this field.
12 citations
TL;DR: In this article , the authors used Ishihara-style stimulus patterns to examine thresholds for 21 directions at five locations in colour space for the fish Rhinecanthus aculeatus and found that thresholds matched RNL model predictions most closely for stimuli near the achromatic point, but exceeded predictions with distance from this point.
Abstract: ABSTRACT Animals use colour vision in a range of behaviours. Visual performance is limited by thresholds, which are set by noise in photoreceptors and subsequent neural processing. The receptor noise limited (RNL) model of colour discrimination is widely used for modelling colour vision and accounts well for experimental data from many species. In one of the most comprehensive tests yet of colour discrimination in a non-human species, we used Ishihara-style stimulus patterns to examine thresholds for 21 directions at five locations in colour space for the fish Rhinecanthus aculeatus. Thresholds matched RNL model predictions most closely for stimuli near the achromatic point, but exceeded predictions (indicating a decline in sensitivity) with distance from this point. Thresholds were also usually higher for saturation than for hue differences. These changes in colour threshold with colour space location and direction may give insight into photoreceptor non-linearities and post-receptoral mechanisms of colour vision in fish. Our results highlight the need for a cautious interpretation of the RNL model – especially for modelling colours that differ from one another in saturation (rather than hue), and for highly saturated colours distant from the achromatic point in colour space.
8 citations
TL;DR: In this article , the authors investigated whether edge statistics accurately predict the detection of prey by potential predators, and they found various statistically significant correlations between edge statistics and detection speed depending on treatment and viewing distance.
Abstract: ABSTRACT 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 analysis software and their application across non-human visual systems. Here, we investigated whether Boundary Strength Analysis (BSA), Local Edge Intensity Analysis (LEIA) and the Gabor edge disruption 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.
5 citations
TL;DR: In this article , the authors quantified the chromatic and achromatic detectability and boldness of colour patterns in 13 nymphs that varied in the strength of their chemical defences, in terms of unpalatability and toxicity, using Quantitative Colour Pattern Analysis (QCPA).
Abstract: Aposematic signals advertise underlying defences in many species. They should be detectable (highly contrasting against the background) and bold (high internal pattern contrast) to enhance predator recognition, learning and memorisation. However, the signalling function of aposematic colour patterns may be distance-dependent: signals may be undetectable from a distance to reduce costs of increased attacks from naïve predators but bold when viewed up close. To test this hypothesis, we quantified the chromatic and achromatic detectability and boldness of colour patterns in 13 nudibranch species that varied in the strength of their chemical defences, in terms of unpalatability and toxicity, using Quantitative Colour Pattern Analysis (QCPA) and data on the visual perception of a triggerfish (Rhinecanthus aculeatus). When viewed from larger distances, there were no differences in detectability and boldness between well-defended and undefended species. However, when viewed at close distances, well-defended species were more detectable and bolder than undefended species. The detectability of defended species decreased more significantly with increased viewing distances compared to boldness but remained relatively consistent over viewing distances for undefended species. We provide evidence for distance-dependent signalling in aposematic nudibranchs and highlight the importance of distinguishing between signal detectability and boldness in studies of aposematism.
2 citations
TL;DR: In this paper , negative frequency-dependent selection has been proposed as one of the most powerful selective forces in maintaining phenotypic and genetic diversity in both plant and animal populations, in which the fitness of a phenotype decreases with its frequency.
1 citations
TL;DR: In this paper , the authors investigate how combinations of multiple male phenotypic traits (both within and across sensory modalities) predict male mating and fertilization success in the critically endangered southern corroboree frog, Pseudophryne corrobatoree .
Abstract: Abstract Complex sexual signals spanning multiple sensory modalities may be common in nature, yet few studies have explored how combinations of phenotypic traits influence male attractiveness and mating success. Here, we investigate whether combinations of multiple male phenotypic traits (both within and across sensory modalities) predict male mating and fertilization success in the critically endangered southern corroboree frog, Pseudophryne corroboree . We conducted breeding trials in a standardized captive environment where females were given the opportunity to choose between multiple males over the duration of the breeding season. For each male, we measured multiple call traits, aspects of coloration, body size, and age. We found that complex interactions between multiple traits best predicted male mating and fertilization success. In general, males with lower call frequency, lower call rate, and shorter call duration had the highest mating and fertilization success. Fertilization success was additionally linked to male body size and age. These findings suggest that female P. corroboree select mates based on a suite of acoustic traits, adding to a growing body of evidence that females use multiple traits to assess male quality. Our results also suggest that females may combine information from multiple signals non-additively. Moreover, our results imply that females gain direct fertility benefits from their mate choice decisions. We argue that understanding female mate choice based on various signals across multiple sensory modalities has important implications for the integration of mate choice into conservation breeding programs and needs to be considered when developing behavior-based captive breeding strategies. Significance statement Sexual signals are often highly complex, yet we know little about how multiple signal components both within and across various sensory modalities predict male mating success. We investigated whether combinations of multiple phenotypic traits (within and across sensory modalities) predicted male breeding success in threatened corroboree frogs. We conducted captive breeding trials in a homogeneous environment, where females could choose between multiple males over the duration of a single breeding season. We found that interactions between multiple male traits predicted mating and fertilization success. Males with lower call frequency, call rate, and duration had higher mating success. Fertilization success was also linked to acoustic signals, body size, and age. Understanding mate choice for multiple traits further elucidates the complexity of female mate choice. This study is one of the first to consider the conservation implications of multimodal signaling in mate choice.
1 citations
TL;DR: It is concluded that the orientation of courting pairs and the ambient light spectrum should be accounted for in studies of mate choice, because the visual background and light affect visibility, and these differ with orientation.
Abstract: Male guppies (Poecilia reticulata) have multiple colored spots and perform courtship displays near the edges of streams in Trinidad in shallow water flowing through rainforest. Depending upon the orientation of the pair, the female sees the male displays against gravel or other stream bed substrates or against the spacelight—the roughly uniform light coming from the water column away from the bank. We observed courting pairs in two adjacent natural streams and noted the directions of each male display. We found that the female sees the male more often against spacelight than against gravel when females either faced the spacelight from the opposite bank or from downstream, or both. Visual modelling using natural substrate reflectances and field light measurements showed higher chromatic contrast of males against spacelight than against substrates independent of the two ambient light environments used during displays, but achromatic contrast depended upon the ambient light habitat. This suggests that courtship involves both chromatic and achromatic contrast. We conclude that the orientation of courting pairs and the ambient light spectrum should be accounted for in studies of mate choice, because the visual background and light affect visibility, and these differ with orientation.
1 citations
TL;DR: In this paper , the authors investigated bower acoustic properties by playing standard sounds from multiple court positions and recorded the resulting sounds at the female's typical avenue head position within the avenue.
Abstract: Great bowerbird males build bowers for attracting females for mating. Bowers consist of a thatched twig tunnel (avenue) which opens onto two flat courts covered with objects. Male displays on a court are seen by a female from within the avenue. She sees and hears displays through the avenue entrance but can only see the male’s head and objects in his bill as it passes repeatedly across the entrance. We investigated bower acoustic properties by playing standard sounds from multiple court positions and recorded the resulting sounds at the female’s typical avenue head position within the avenue. Bower geometry significantly affects both his acoustic and visual display components and physically synchronizes them as he repeatedly moves in and out of the female’s view. Consequently, complex neural circuitry is unnecessary for linking sound to vision. Experimentally removing bower objects shows that objects significantly increase higher frequencies, hence bandwidth and loudness received inside the avenue. Great Bowerbird bowers produce a synchronized multimodal signal to females which may increase male attractiveness more than if a single sensory mode were used. This multimodal signal is unusual in that it is constructed rather than being part of the body and synchronized as a result of physics rather than neurons. Summary Statement Bowerbird bower geometry jointly effects both visual and auditory signal components and synchronizes them without the need for additional neural circuitry.
TL;DR: In this paper , the authors propose an approach to solve the problem of "uniformity" and "uncertainty" in the context of video games.20.6.20
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TL;DR: It is shown that the same selective conditions that promote the maintenance of polymorphism within populations reduce the likelihood of divergence in aposematic traits among populations.
Abstract: Abstract Maintenance of variation in aposematic traits within and among populations is paradoxical because aposematic species are normally under positive frequency‐dependent predation (PFD), which is expected to erode variation. Aposematic traits can evolve in an ecological context where aposematic traits are simultaneously under mate choice. Here, we examine how the mate preference intensity affects the permissiveness of polymorphism in sexually selected aposematic traits under different PFD regimes. We use the haploid version of the classical sexual selection model and show that strong mate preferences can substantially increase the permissiveness of polymorphism in aposematic traits under different PFD regimes. The Fisher process can interact with PFD, and their interaction can promote the maintenance of polymorphism within populations when mate preferences are strong. We show that the same selective conditions that promote the maintenance of polymorphism within populations reduce the likelihood of divergence in aposematic traits among populations.