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Animal Vigilance builds on the author's previous publication with Academic Press (Social Predation: How Group Living Benefits Predators and Prey) by developing several other themes including the development and mechanisms underlying vigilance, as well as developing more fully the evolution and function of vigilance.Animal vigilance has been.

Marine natural products play critical roles in the chemical defense of many marine organisms and in some cases can influence the community structure of entire ecosystems. Although many marine natural products have been studied for biomedical activity, yielding important information about their biochemical effects and mechanisms of action, much less is known about ecological functions. The way in which marine consumers perceive chemical defenses can influence their health and survival and determine whether some natural products persist through a food chain. This article focuses on selected marine natural products, including okadaic acid, brevetoxins, lyngbyatoxin A, caulerpenyne, bryostatins, and isocyano terpenes, and examines their biosynthesis (sometimes by symbiotic micro-organisms), mechanisms of action, and biological and ecological activity. We selected these compounds because their impacts on marine organisms and communities are some of the best-studied among marine natural products. We discuss the effects of these compounds on consumer behavior and physiology, with an emphasis on neuroecology. In addition to mediating a variety of trophic interactions, these compounds may be responsible for community-scale ecological impacts of chemically defended organisms, such as shifts in benthic and pelagic community composition. Our examples include harmful algal blooms; the invasion of the Mediterranean by Caulerpa taxifolia; overgrowth of coral reefs by chemically rich macroalgae and cyanobacteria; and invertebrate chemical defenses, including the role of microbial symbionts in compound production.

Inking by marine molluscs such as sea hares, cuttlefish, squid, and octopuses is a striking behavior that is ideal for neuroecological explorations. While inking is generally thought to be used in active defense against predators, experimental evidence for this view is either scant or lacks mechanistic explanations. Does ink act through the visual or chemical modality? If inking is a chemical defense, how does it function and how does it affect the chemosensory systems of predators? Does it facilitate escape not only by acting directly on predators but also by being an alarm signal for conspecifics? This review examines these issues, within a broader context of passive and active chemical defensive secretions. It focuses on recent work on mechanisms of defense by inking in sea hares (Aplysia) and extends what we have learned about sea hares to other molluscs including the cephalopods.

Nest predation has driven the evolution of specialized behaviors that decrease the probability that a predator encounters a nest. We collected descriptions from the literature of a behavior wherein male and female adults fly to their nest as a pair, with one bird flying onward or veering off while the other enters the nest. We suggest that the most likely function of this behavior is to decrease the risk of nest predation from visual nest predators. In this hypothesis, visual nest predators are distracted by the flying bird and thus fail to observe the bird arriving to the nest entrance (and the nest itself), although the putative adaptive value of this behavior remains to be confirmed. While this behavior has been sporadically noted in the natural history literature, few ornithologists are aware it is found across multiple taxa, especially in the Neotropics. We show that this behavior occurs in at least 28 species across 5 distinct families (and 11 genera) of passerines. We propose a classification scheme for this and similar behaviors and discuss factors hypothesized to promote the evolution of this behavior (e.g., mate guarding, building enclosed nests). We call this behavior \"coordinated misdirection\" (or \"desvio coordinado\" in Spanish) because it depends on the cooperation of at least 2 birds, and its presumed function is a visual misdirection--a ruse to draw the observers' attention away from the nest. Finally, we encourage future research so that the evolutionary history of the behavior can be explored and the behavior can be analyzed under a life history framework. Received 24 March 2017. Accepted 18 March 2018. Key words: antipredator behavior, breeding biology, distraction display, dynamic nest-crypsis behavior, natural history, nest defense. La depredacion de nidos ha impulsado la evolucion de comportamientos especializados que disminuyen la probabilidad de que un depredador encuentre a un nido. Recolectamos descripciones de la literatura sobre un comportamiento donde los adultos macho y hembra vuelan al nido en pareja, con un pajaro siguiendose de largo o desviandose mientras que el otro entra al nido. Sugerimos que la funcion mas probable de este comportamiento es disminuir el riesgo de depredacion del nido de parte de depredadores de nidos que usan senales visuales. Segun esta hipotesis, depredadores de nidos visuales son distraidos por el ave que sigue en vuelo y no llegan a observar al ave que llega a la entrada del nido (o al mismo nido), aunque el supuesto valor adaptive del comportamiento aun debe ser continuado. Mientras que este comportamiento ha sido notado esporadicamente en la literatura de historia natural, pocos ornitologos se han percatado de que se encuentra en varios taxones, especialmente en los neotropicos. Demostramos que este comportamiento ocurre en un minimo de 28 especies en cinco familias diferentes (y 11 generos) de Passed formes. Proponemos un sistema de clasificacion para este y comportamientos parecidos y discutimos factores que hipoteticamente promueven la evolucion de este comportamiento (por ejemplo, la vigilancia de la pareja, la construccion de nidos encerrados). Llamamos a este comportamiento \"desvio coordinado\" porque depende de la cooperacion de al menos dos aves y su supuesto funcion es un truco visual--una tactica para llamar la atcncion del observador lejos del nido. Finalmente, espcramos que flituras investigaciones puedan explorar la historia evolutiva de este comportamicnto y que puedan analizarlo dentro de la estruetura de la teoria de la historia de vida. Palabras clave: biologia de la rcproduccion, comportamiento anti-depredadores, comportamiento de ocultamiento de nidos dinamieo, defensa del nido, distraccion anti-depredadores, historia natural.

Many prey react to predation risk by altering their phenotype to reduce their chances of being consumed but incur reductions in growth and fecundity when reacting to predators. To determine when to produce defenses, prey collect information and evaluate the costs and benefits of defense induction. Resource availability can affect prey ability and willingness to incur defense costs. When resources are scarce, defenses may suffer disproportionate decreases in energy allocation if defenses would further reduce prey access to resources or if resources are needed to maintain metabolic functions. We tested the effects of predation risk and resource availability on plastic defenses in eastern oysters Crassostrea virginica and present novel findings that oysters continued to produce defended shells in response to predators when resources were limited, even though they grew smaller, lighter shells when deprived of food in control conditions. Predation risk affected all three tested shell metrics (area, weight, and strength), but food availability did not. Although low food levels often limit expression of predator defenses, predator cues caused oysters to build shells that were larger and heavier, with a similar trend for shell strength, in treatments with both low and high food levels, suggesting that predation is an important pressure in this system. The differences between predator and control treatments were greater under conditions of low food availability, and thus, resource availability may influence interpretations of plastic responses to predators.

Marine gastropods exhibit a stunning diversity of shell sculpture, but the functional significance of many sculpture types remains unknown. Unfortunately, experimental tests of the functional significance of differences between species are complicated by other morphological differences, such as shell microstructure, aperture shape, and shell thickness, that may confound interpretation. The most robust experimental tests are therefore performed using different shell forms within a species. We took advantage of the extensive intraspecific shell variation in the common intertidal gastropod Nucella lamellosa to test the adaptive significance of axial lamellae, a type of shell sculpture found in numerous marine gastropod subfamilies. We offered three forms of N. lamellosa (lamellose, artificially smooth, and naturally smooth) to the predatory sea star Pisaster ochraceus under controlled laboratory conditions. Pisaster ochraceus consumed significantly fewer lamellose snails than either artificially or naturally smooth snails. We suggest that shell lamellae deter sea star predation by impairing their ability to capture or manipulate snail prey or by increasing prey effective size. These results suggest a credible hypothesis for the adaptive significance of lamellar sculpture in marine gastropods and provide a valuable missing piece to the story about adaptive phenotypic plasticity in N. lamellosa shell form.

Animals and vascular plants are known to defend themselves facultatively against pathogens, with innate receptors mediating their resistance. Macroalgal defense against microorganisms, in contrast, has until recently been regarded mainly as constitutive. Indeed, many macroalgae appear to be chemically defended at constantly high levels, and this is possibly one of the reasons why the first evidence of pathogen-aroused resistance in a macroalga was detected only a decade ago. Here, I summarize the results of studies that indicate the existence of pathogen-activated or pathogen-induced macroalgal defense. Most indications so far come from molecular investigations, which revealed major functional similarities among the defense systems of distant macroalgal clades and the innate immune systems of vascular plants and metazoans. Homologies exist in the primary and secondary defense-activating signals, as well as in the enzymes that are involved and the cellular responses that are activated. This strongly suggests that innate immunity also exists in relatively distinct macroalgal clades. However, a macroalgal receptor still needs to be isolated and characterized, and the molecular concept of macroalgal receptor-mediated immunity needs to be complemented with an ecological perspective on pathogen-induced defense, to develop a joint neuroecological perspective on seaweed-microbe interactions.

Cuttlefish use multiple camouflage tactics to evade their predators. Two common tactics are background matching (resembling the background to hinder detection) and masquerade (resembling an uninteresting or inanimate object to impede detection or recognition). We investigated how the distance and orientation of visual stimuli affected the choice of these two camouflage tactics. In the current experiments, cuttlefish were presented with three visual cues: 2D horizontal floor, 2D vertical wall, and 3D object. Each was placed at several distances: directly beneath (in a circle whose diameter was one body length (BL); at zero BL [(0BL); i.e., directly beside, but not beneath the cuttlefish]; at 1BL; and at 2BL. Cuttlefish continued to respond to 3D visual cues from a greater distance than to a horizontal or vertical stimulus. It appears that background matching is chosen when visual cues are relevant only in the immediate benthic surroundings. However, for masquerade, objects located multiple body lengths away remained relevant for choice of camouflage.

Many prey species (including plants) deter predators with defensive chemicals. These defensive chemicals act by rendering the prey's tissues noxious, toxic, or both. Here, I explore how predators cope with the presence of these chemicals in their diet. First, I describe the chemosensory mechanisms by which predators (including herbivores) detect defensive chemicals. Second, I review the mechanisms by which predators either avoid or tolerate defensive chemicals in prey. Third, I examine how effectively free-ranging predators can overcome the chemical defenses of prey. The available evidence indicates that predators have mixed success overcoming these defenses. This conclusion is based on reports of free-ranging predators rejecting unpalatable but harmless prey, or voluntarily ingesting toxic prey.