Genetic algorithms have provided a potential method for accounting for these interactions, but with limited accessibility. However, the vast diversity of colour 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. Within population phenotypic variance therefore does not seem to be indicative of strong selection toward multiple signaling strategies, but rather pattern divergence has likely arisen due to weak purifying selection, or neutral processes, on a signal that is highly salient to both conspecifics and predators.Ĭamouflage 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. Similarly, we found no evidence that frog color pattern contrast was either enhanced or diminished in the frogs’ chosen microhabitats compared to alternative patches in which conspecifics were observed. We found that, despite considerable color pattern variation, variance could not be partitioned into distinct groups, but rather all viewers would be likely to perceive variation as continuous. We used visual modeling of conspecific and heterospecific observers to quantify the extent of within population phenotypic variation and assess whether this variation produced distinct signals. Alternatively, variance could simply be due to relaxed selection, where variation would be predicted to be continuous. On one hand, color pattern polymorphism could be the result of multifarious selection acting to balance different signaling functions and leading to the evolution of discrete sub-morphs which occupy different fitness peaks. We comprehensively sampled a subpopulation of the poison frog Oophaga sylvatica, a species which is polytypic across its distribution and also shows considerable within-population polymorphism. Despite increases in the frequency with which polytypism and polymorphism have been suggested to occur, population-wide variance is rarely quantified. Variation in aposematic signals was once predicted to be rare, yet in recent years it has become increasingly well documented. The colour and pattern variables of spider prey were consistent over time, suggesting that individual search images may strengthen with experience. These findings highlight the specific visual features that may be the focal trait during search image formation in these wasps. Our results show that the wasps are choosing a small group of orb weavers (Araneidae) with similar coloration and body patterns. Those visual traits were compared at the community and nest cell levels, according to the nest provisioning sequence, and its relationship with spider diversity. Using psychophysical visual modelling from multispectral digital photography, we measured the colour and body pattern of the spiders captured and stored in nests by the wasp Trypoxylon mexicanum. However, the search image concept in wasps has not been evaluated from a visual ecology perspective. Mud dauber wasps exhibit individual specialization and consistency in prey preferences through time, often based on visual and chemical cues, that may vary at intraspecific levels. In hymenopterans, examples include floral search images in bees and acquired sensory biases towards specific prey in wasp predators. Search images are perceptual biases acquired through experience that improve an individual’s ability to detect the object of their search (e.g., a predator seeking prey). Chapter 6 describes mathematical methods and software on statistical signal discrimination that we developed to solve questions in visual detection, but with wider applications in other fields. Chapter 5 is a reference on some methods and analysis used in the study. In chapter 3, we present a series of experiments which measured human camouflage detection ability along different dimensions of the task, such as across different textures and shapes. In chapter 2, we develop a theory and model that extracts the relevant information in the image, and uses biologically plausible computations on them for detection. Chapter 1 introduces and contextualizes the problem. whose texture exactly mimics the background texture. In this thesis, we investigate the principles of human detection of maximally-camouflaged objects, i.e. They are the result of an evolutionary arms race that exposes many detection strategies and their limits. Camouflage is an amazing feat of evolution, but also impressive is the ability of biological visual systems to detect them.
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