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Este artículo contiene 12 páginas, 4 figuras, 1 tabla., Background: Classic ecological formulations of predator–prey interactions often assume that predators and prey interact randomly in an information-limited environment. In the feld, however, most prey can accurately assess predation risk by sensing predator chemical cues, which typically trigger some form of escape response to reduce the probability of capture. Here, we explore under laboratory-controlled conditions the long-term (minutes to hours) escaping response of the sea urchin Paracentrotus lividus, a key species in Mediterranean subtidal macrophyte communities. Methods: Behavioural experiments involved exposing a random sample of P. lividus to either one of two treatments: (i) control water (fltered seawater) or (ii) predator-conditioned water (with cues from the main P. lividus benthic predator—the gastropod Hexaplex trunculus). We analysed individual sea urchin trajectories, computed their heading angles, speed, path straightness, difusive properties, and directional entropy (as a measure of path unpredictability). To account for the full picture of escaping strategies, we followed not only the frst instants post-predator exposure, but also the entire escape trajectory. We then used linear models to compare the observed results from control and predators treatments. Results: The trajectories from sea urchins subjected to predator cues were, on average, straighter and faster than those coming from controls, which translated into diferences in the difusive properties and unpredictability of their movement patterns. Sea urchins in control trials showed complex difusive properties in an information-limited environment, with highly variable trajectories, ranging from Brownian motion to superdifusion, and even marginal ballistic motion. In predator cue treatments, variability reduced, and trajectories became more homogeneous and predictable at the edge of ballistic motion. Conclusions: Despite their old evolutionary origin, lack of cephalization, and homogenous external appearance, the trajectories that sea urchins displayed in information-limited environments were complex and ranged widely between individuals. Such variable behavioural repertoire appeared to be intrinsic to the species and emerged when the animals were left unconstrained. Our results highlight that fear from predators can be an important driver of sea urchin movement patterns. All in all, the observation of anomalous difusion, highly variable trajectories and the behavioural shift induced by predator cues, further highlight that the functional forms currently used in classical predator–prey models are far from realistic., The Spanish Ministry of Science and Innovation funded this research (project CTM2010-22273-C02, CTM2017-86695-C3-1-R, CTM2017-86695-C3-3-R, and CGL78156-C2-R1). JFP acknowledges fnancial support from the Spanish Ministry of Education (scholarship AP2008-01601) and the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 795315.

Predators alter prey populations via direct lethality (density‐mediated effects), but in many taxa, the indirect nonlethal threat of predation may be almost as strong an effect, altering phenotypically plastic traits such as prey morphology, behavior, and life history (trait‐mediated effects). There are costs to antipredator defenses and the strength of prey responses to cues of predation likely depends on both the perceived level of risk and food availability.The goal of this study was to test the hypothesis that the costs of nonlethal trait‐mediated interactions impacting larvae can have carryover effects that alter life‐history traits, adult characteristics, and ultimately population dynamics.The effects of Toxorhynchites rutilus kairomones and chemical alarm cues on Aedes triseriatus were assessed in a two‐level factorial design manipulating nutrient level (low or high) and chemical cues of predation (present or absent).Nonlethal chemical cues of predation significantly decreased female survivorship and significantly decreased female size. Females emerged as adults significantly earlier when exposed to predation cues when there was high nutrient availability. When raised in the low nutrient treatment and exposed to predator cues, adult females had 2.1 times the hazard of death compared to high nutrient‐no predator cues. Females raised in the high nutrient and predator cue treatment blood fed sooner than did females from other combinations.Fear of predation can substantially alter prey life‐history traits and behavior, which can cascade into dramatic population, community, and ecosystem effects. Exposure to predator cues significantly decreased the estimated cohort rate of increase, potentially altering the expected population density of the next generation.

The molecular mechanisms underlying the conspecific cue-mediated larval settlement in Crassostrea gigas is not yet fully understood. In this study, we described and compared the transcriptomes of competent pediveligers (Pedi) and conspecific cue-induced postlarvae (PL). A total of 2383 candidate transcripts were identified: 740 upregulated and 1643 downregulated transcripts, after settlement. Gene Ontology analysis revealed active chitin binding, calcium ion binding, and extracellular region processes in both stages. Results showed that the differential expression trend of six candidate transcripts were consistent between the quantitative real-time PCR and transcriptome data. The differential transcript expression related to shell formation showed closely linked dynamics with a gene regulatory network that may involve the interplay of various hormone receptors, neurotransmitters, and neuropeptide receptors working together in a concerted way in the Pedi and PL stages. Our results highlight the transcriptome dynamics underlying the settlement of oysters on conspecific adult shells and demonstrate the potential use of this cue as an attractant for wild and hatchery-grown oyster larval attachment on artificial substrates. It also suggests the possible involvement of an ecdysone signal pathway that may be linked to a neuroendocrine-biomineralization crosstalk in C. gigas settlement., Diversity, 14 (7), art. no. 559; 2022

Made available in DSpace on 2018-12-11T17:22:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-01-01 Fiddler crabs are intertidal organisms well known to be highly adapted to low tide activity, thus a number of researches have studied their physiological, behavioral and sensory adaptations to such a tidal phase. However, recent evidences showed that some fiddler crabs are the main food item of fish, suggesting that they could also be active underwater. Based on these preliminary observations, we designed laboratory trials aimed to investigate the ability to detect underwater predators in Leptuca thayeri, across sexes and life stages. We tested a combination of chemical and visual cues, using the predator fish Sphoeroides greeleyi, and, as a control, the non-predator fish Mugil curema. Leptuca thayeri detected the presence of chemical cues coming from the predator fish, although significant differences between adults and juveniles were observed. Adults of L. thayeri remained within their burrows and avoided predator exposition, while juveniles were bold and even increased their activity on the sediment surface. We suggest that juvenile crabs’ boldness could be explained by a predator inspection behavior, which allows them to gather information about the possible risk of different predatory species, while experienced adults reduce predation risk recognizing the predator itself. Postgraduate Program in Biological Sciences (Zoology) Botucatu Biosciences Institute São Paulo State University–UNESP The Swire Institute of Marine Science and School of Biological Sciences University of Hong Kong, Pokfulam Road Department of Biology University of Florence, Via Madonna del Piano 6 Laboratory of Ecology and Animal Behavior Coastal Campus Biosciences Institute São Paulo State University–UNESP Postgraduate Program in Biological Sciences (Zoology) Botucatu Biosciences Institute São Paulo State University–UNESP Laboratory of Ecology and Animal Behavior Coastal Campus Biosciences Institute São Paulo State University–UNESP

The ubiquitous oceanic copepod Calanus finmarchicus is the major link between primary producers and important fish stocks in the North Atlantic Ocean and adjacent seas. Despite over a century of research on growth and development of this key species, the effect of predation risk on these processes remains elusive. We tested how food level and chemical cues from a fish predator influence growth and development of C. finmarchicus, using a predator naïve laboratory population. Copepods reached adult stage earlier both in response to high food and to predator cues in our experiment. High food also increased growth and lipid accumulation. In contrast, perceived predation risk triggered reduced size and lipid fullness, indicating a decoupling of growth and development rates. Our results demonstrate that chemical predator cues can influence life history strategies in C. finmarchicus, and suggest that present and future patterns in oceanic zooplankton size and population dynamics may also reflect differences in predation risk. © 2020 The Authors. Ecology published by Wiley Periodicals LLC on behalf of Ecological Society of America This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Laboratory experiments have shown that the viability of embryos of the invasive cane toad (Rhinella marina) can be reduced by exposure to chemical cues from older conspecific larvae. These effects (very strong in laboratory trials) may offer an exciting new approach to controlling this problematic invasive species in Australia. However, the degree to which the method works in natural environments has yet to be assessed.Our experiments in the laboratory and in seminatural outdoor waterbodies show that chemical cues from tadpoles do indeed suppress the growth, development, and survival of conspecific larvae that are exposed as embryos and do so in a dose‐dependent manner; higher tadpole densities cause greater suppression of embryos.In seminatural outdoor waterbodies, suppressor‐exposed tadpoles were less than half as likely to survive to metamorphosis as were controls, and were much smaller when they did so and hence, less likely to survive the metamorph stage. Additionally, female cane toads were less likely to oviposit in a waterbody containing free‐ranging (but not cage‐enclosed) tadpoles, suggesting that the presence of tadpoles (rather than the chemical cues they produce) may discourage oviposition.Broadly, our results suggest that the suppression effect documented in laboratory studies does indeed occur in the field also, and hence that we may be able to translate that approach to develop new and more effective ways to reduce rates of recruitment of peri‐urban populations of cane toads in their invasive range., When cane toad eggs are exposed to cane toad tadpoles during development, the eggs often experience stunted development and do not produce viable tadpoles. While adult toads will avoid laying their eggs in ponds containing toad tadpoles, this behavior does not occur if the tadpoles are contained within a small net. This is encouraging for the control of cane toads in Australia as it suggests that adult toads can be manipulated into laying their eggs into ponds where their clutch will not develop into successful tadpoles.

Lay Summary Males adjust both courtship effort and ejaculate expenditure when mating with females that are coated in the chemical cues of other males. Using a manipulative approach, we show that male flour beetles use the chemical cues of rival males left behind on virgin female cuticles to assess sperm competition risk. These cues do not make virgin females more chemically similar to mated females but appear to allow males to indirectly assess competition within the population., Males can gather information on the risk and intensity of sperm competition from their social environment. Recent studies have implicated chemosensory cues, for instance cuticular hydrocarbons (CHCs) in insects, as a key source of this information. Here, using the broad-horned flour beetle (Gnatocerus cornutus), we investigated the importance of contact-derived rival male CHCs in informing male perception of sperm competition risk and intensity. We experimentally perfumed virgin females with male CHCs via direct intersexual contact and measured male pre- and post-copulatory investment in response to this manipulation. Using chemical analysis, we verified that this treatment engendered changes to perfumed female CHC profiles, but did not make perfumed females “smell” mated. Despite this, males responded to these chemical changes. Males increased courtship effort under low levels of perceived competition (from 1–3 rivals), but significantly decreased courtship effort as perceived competition rose (from 3–5 rivals). Furthermore, our measurement of ejaculate investment showed that males allocated significantly more sperm to perfumed females than to control females. Together, these results suggest that changes in female chemical profile elicited by contact with rival males do not provide males with information on female mating status, but rather inform males of the presence of rivals within the population and thus provide a means for males to indirectly assess the risk of sperm competition.

We explore for the first time the relative importance of chemical and visual cues of predators in nest defense and antipredator behavior in a hole-nesting songbird, the blue tit Cyanistes caeruleus. Birds breeding in nest boxes were exposed to chemical or visual cues of a predatory and a non-predatory mammal during the nestling stage, and their behavior both outside and inside nest boxes was recorded with video films. Our results show that birds respond equally to chemical and to visual cues of predators in a context of nest defense. Adult birds minimized predation risk by decreasing the time spent inside the nest box while feeding nestlings when they were exposed to either visual or chemical cues of a mammalian predator. They decreased the time spent in non-essential activities for nestlings¿ survival, such as nest sanitation activities, but they maintained provisioning rates so that the nestlings¿ growth was not compromised. In this way, birds minimized the risk of predation while provisioning nestlings when a predator was detected in the vicinity of their nest., LA was supported by the Ramón y Cajal program and the CGL2014-58890-P project

1. To reduce the risk of being eaten by predators, prey alter their morphology or behaviour. This response can be tuned to the current danger if chemical or other cues associated with predators inform the prey about the risks involved. 2. It is well known that various prey species discriminate between chemical cues from predators that fed on conspecific prey and those that fed on heterospecific prey, and react stronger to the first. It is therefore expected that generalist predators are more successful in capturing a given prey species when they are contaminated with chemical cues from another prey species instead of cues from the same prey species. 3. Here, a generalist predatory mite was studied that feeds on thrips larvae as well as on whitefly eggs and crawlers. Mites were marked with cues (i.e. body fluids) of one of these two prey species and were subsequently offered thrips larva. 4. Predators marked with thrips cues killed significantly fewer thrips than predators marked with whitefly cues, even though the predator's tendency to attack was the same. In addition, more thrips larvae sought refuge in the presence of a predatory mite marked with thrips cues instead of whitefly cues. 5. This suggests that generalist predators may experience improved attack success when switching prey species. R.v.M. received a scholarship of the Technology Foundation (STW Project 7180). G.B. received a fellowship from the OECD. E.A.F. received a fellowship from Fundació Caixa Castelló-Bancaixa (E-2011-09)

Attached is the complete raw data from Dixson et al. 2014 "Chemically mediated behavior of recruiting corals and fishes: A tipping point that may limit reef recovery." Data has been inputted into Excel with different tabs that are color coded. All data corresponding to fish behavioral choice data collected using a 2 chamber Atema flume can be found in red. Data for the fish species have been further broken into 15 separate tabs, each corresponding to a different fish species tested. All data corresponding to the coral behavioral choice data collected using a 2 chamber Atema flume can be found in yellow. Laboratory settlement data for coral preferences can be found in green. Field recruitment data for both fish and corals are labeled in blue, using 2 separate tabs. Chemical choice flume data for fishes recorded the individual position in either water stream taken every 5 seconds for 2 minutes. The water sources were then switched and an additional 2 minute test period occurred with the position of the individuals recorded again every 5 seconds. Resulting in a total of 48 position points recorded. Data is set up so that an individual is recorded per row. The first part of the trial for each individual is found in the first two columns, after the water is switched the data for the second part of the trial is found in columns three and four. For example, on the first tab, for Chromis viridis, water from the MPA and Non-MPA taken from Votua Village were tested against each other. Column L and M have data from the first part of the trial, column N and O have data after the water sources were switched. The score in column P is the total times an individual was in one of the columns, in this example the MPA water from Votua village. The individual average, column Q, is the score data, column P, divided by 48 and multiplied by 100, resulting in the percent time spent in one water source. Below the individual average column for each set of chemical data is the mean average, standard deviation and standard error. Coral choice data is set up identical to the fish data however instead of recordings taken every 5 seconds for 2 minutes, coral behavioral data was taken for 3 minutes, therefore a total position recorded is 72.

Females of most aculeate Hymenoptera mate only once and males are therefore under a strong competitive pressure which is expected to favour the evolution of rapid detection of virgin females. In several bee species, the cuticular hydrocarbon (CHC) profile exhibited by virgin females elicits male copulation attempts. However, it is still unknown how widespread this type of sexual communication is within Aculeata. Here, we investigated the use of CHCs as mating cues in the digger wasp Stizus continuus, which belongs to the family (Crabronidae) from within bees arose. In field experiments, unmanipulated, recently emerged virgin female dummies promptly elicit male copulation attempts, whereas 1-4days old mated females dummies were still attractive but to a much lesser extent. In contrast, old (10-15days) mated female dummies did not attract males at all. After hexane-washing, attractiveness almost disappeared but could be achieved by adding CHC extracts from virgin females even on hexane-washed old mated females. Thus, the chemical base of recognition of females as appropriate mating partner by males is coded in their CHC profile. Accordingly, differences in CHC profiles can be detected between sexes, with males having larger amounts of alkenes and exclusive long-chain alkanes, and within females specially according to their mating status. Shortly after mating, almost all of the major hydrocarbons found on the cuticle of females undergo significant changes in their abundance, with a clear shift from short-chain to long-chain linear and methyl-branched alkanes. The timely detection of virgin females by males in S. continuus could be advantageous within the narrow period of female emergence, when male-male competition is strongest.

Made available in DSpace on 2018-12-11T17:07:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-12-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) In fish, defensive reactions are induced by different chemical cues that emanate from sense-related stresses [physical, chemical, and visual (visual contact with predator)] or food stresses (acute fasting and chronic food restriction). Using a shuttle box with a two-chamber unmixed laminar flow that allowed fish to remain or flee from a chemical cue, we showed that the avoidance response depended on the type of the chemical cue. We show that zebrafish (Danio rerio) retreated from water conditioned with chemical cues released by chemically or physically stressed fish and acutely fasted fish, but not from water with cues from fish experiencing visual contact with predatory fish or fish suffering from chronic food restriction. Our data reinforced the hypothesis that fish use a combination of information and the context of the situation to determine their evasion strategy. Programa de Pós-Graduação em Farmacologia Universidade Federal de Santa Maria (UFSM) Universidade de Passo Fundo (UPF) Programa de Pós-Graduação em Bioexperimentação Universidade de Passo Fundo (UPF) Department of Physiology Institute of Biosciences of Botucatu Caunesp Unesp Centro Universitário La Salle-Unilasalle Programa de Pós-Graduação em Avaliação de Impactos Ambientais Department of Physiology Institute of Biosciences of Botucatu Caunesp Unesp CNPq: 301992/2014-2 CNPq: 302719/2013-0

Antipredatory defenses are maintained when benefit exceeds cost. A weak predation pressure may lead insular lizards to tameness.Podarcis lilfordiexhibits a high degree of insular tameness, which may explain its extinction from the main island of Menorca when humans introduced predators. There are three species of lizards in Menorca: the nativeP. lilfordi, only on the surrounding islets, and two introduced lizards in the main island,Scelarcis perspicillataandPodarcis siculus. In addition, there are three species of snakes, all introduced: one non-saurophagous (Natrix maura), one potentially non-saurophagous (Rhinechis scalaris) and one saurophagous (Macroprotodon mauritanicus). We studied the reaction to snake chemical cues in five populations: (1)P. lilfordiof Colom, (2)P. lilfordiof Aire, (3)P. lilfordiof Binicodrell, (4)S. perspicillata, and (5)P. siculus, ordered by increasing level of predation pressure. The three snakes are present in the main island, while onlyR. scalarisis present in Colom islet, Aire and Binicodrell being snake-free islets. We aimed to assess the relationship between predation pressure and the degree of insular tameness regarding scent recognition. We hypothesized thatP. lilfordishould show the highest degree of tameness,S. perspicillatashould show intermediate responses, andP. siculusshould show the highest wariness. Results are clear: neitherP. lilfordinorS. perspicillatarecognize any of the snakes, whileP. siculusrecognizes the scent ofM. mauritanicusand reacts to it with typical well-defined antipredatory behaviours as tail waving and slow motion. These results rise questions about the loss of chemical recognition of predators during island tameness and its related costs and benefits for lizards of insular habitats. In addition, this highlights the necessity for strong conservation measures to avoid the introduction of alien predators.

Made available in DSpace on 2018-12-11T17:04:17Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-10-15 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Several fish species exhibit antipredator responses when exposed to chemicals which indicate risk of predation. One such substance is the scent of a predator (a kairomone) that may induce defensive responses in a potential prey. In the present study, we show that chemical cues (odour) from predator fish induce antipredator and stress responses in Nile tilapia. When exposed to predator odour, Nile tilapia decreased activity and increased ventilation rate (VR), but no increase in plasma levels of cortisol and glucose was found. Although the hypothalamic-pituitary-interrenal axis (HPI axis) was not activated, an increase in ventilation is a fast response which can provide the fish enough oxygen for a ‘fight or flight’ event when facing a predator. Thus, this respiratory response suggests an anticipated adjustment in order to prepare the body for a defensive response, such as escaping, irrespective of HPI axis activation. Departamento de Fisiologia Instituto de Biociências UNESP, Rubião Jr. s/n Departamento de Fisiologia Instituto de Biociências UNESP, Rubião Jr. s/n FAPESP: 2010/11319-0 FAPESP: 2011/03216-9

Directional orientation of Clibanarius signatus toward different targets of gastropod shells was studied in a circular arena upon exposure to background seawater, calcium concentrations and predatory odor. Directional orientation was absent when crabs were presented with the white background alone. Each shell was tested in different positions (e.g., anterior, posterior, upside-down, lateral). Adult crabs were tested without their gastropod shells, and orientation varied with concentration and chemical cue. With calcium, orientation increased as concentration increased up to a maximum attraction percentage and then attraction became stable. In the case of predator cues, some individuals swim away from the target toward the opposite direction representing a predator avoidance response. Whenever, the blind hermit crab C. signatus was exposed to a shell target combined with calcium or predator cues, the majority of them stop moving or move in circles around the arena center. The others exhibited uniform orientation distribution. The responsiveness was higher with calcium cues than predator cues. Thus in the absence of vision, individual hermit crabs were able to detect both calcium and predator cues and have different response regarding them.

Whereas many amphibians use olfactory cues to detect aquatic habitats, less attention has been paid to the specificity of the information carried by these cues with respect to breeding habitat quality. In the present work, we address this question by taking advantage of the selectivity for specific breeding habitats exhibited by the natterjack toad (temporary waters, gravel pits). Toads were sampled from two populations located in semi-arid regions of the Iberic peninsula experiencing Mediterranean climate, and one population in a temperate region of France experiencing oceanic-continental climate. The choice was given in a maze between waters coming either from habitats known to be suitable for the species (temporary waters on an inorganic-dominated substratum) or from unsuitable habitats (ponds with eutrophic water or permanent water on organic-rich substratum). The toads from the temperate region exhibited a clear selection for water from the suitable habitat. In contrast, toads from the Mediterranean region did not show any preference, either when the waters came from their original region or when they came from the other region. These results show that toads can use chemical cues to discriminate specific habitats, allowing them to quickly find suitable habitat patches that are temporary and often spatially unpredictable. Variation between the two populations in the ability to select water quality is likely to be connected with habitat availability at the regional scale.

Made available in DSpace on 2018-11-26T16:18:58Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-02-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) In order to maximize escaping success, prey may change their predator avoidance behaviors according to their susceptibility. Morphological development during ontogeny may lead to different susceptibility to predators. Consequently, prey may exhibit different predator avoidance strategies according to the ontogenetic state. In this study, we used tadpoles of the Amazon milk frog Trachycephalus resinifictrix (Anura, Hylidae) to evaluate how variation in the ability to actively escape owed to the mobility acquired through ontogeny affects the adoption of predator avoidance strategies. We sampled tadpoles (N = 384) in temporary ponds and divided them in four consecutive developmental stages according to body size and mobility capacity. Subsequently, we measured their movement and spatial distribution when subjected to chemical cues of predators or control solutions. We found that they spent less time moving and increased spatial aggregation after receiving solutions with predator cues, independent of their developmental stage. These results indicate that the variation in escape capacity through larval ontogeny does not determine their antipredator strategy. Since tadpoles of T. resinifictrix typically grow in environments with reduced space for active escaping, such as tree holes and bromeliads, it may be that the ability to flee from predators is absent, even when this behavior increases the survival chances. Univ Sao Paulo, Dept Physiol, Sao Paulo, Brazil Univ Estadual Paulista, Programa Pos Grad Ecol & Biodiversidade, Rio Claro, SP, Brazil Univ Estadual Feira de Santana, Programa Posgrad Zool, Feira De Santana, BA, Brazil Univ Estadual Paulista, Programa Pos Grad Ecol & Biodiversidade, Rio Claro, SP, Brazil CNPq: 2449505 721687633 FAPESP: 2014/20924-5

Recent studies suggest that direct mortality and physiological effects caused by pollutants are major contributing factors to global amphibian decline. However, even sublethal concentrations of pollutants could be harmful if they combined with other factors to cause high mortality in amphibians. Here we show that sublethal concentrations of pollutants can disrupt the ability of amphibian larvae to recognize predators, hence increasing their risk of predation. This effect is indeed much more important since very low amounts of pollutants are ubiquitous, and environmental efforts are mostly directed towards preventing lethal spills. We analyzed the effects of two common contaminants (humic acid and ammonium nitrate) on the ability of tadpoles of the western spadefoot toad (Pelobates cultripes) to recognize chemical cues from a common predator, nymphs of the dragonfly Anax imperator. We compared the swimming activity of tadpoles in the presence and absence of water-borne chemical cues from dragonflies at different concentrations of humic acid and ammonium nitrate. Tadpoles reduced swimming activity in response to predator cues in the absence of pollutants, whereas they remained unresponsive to these cues when either humic acid or ammonium nitrate was added to the water, even at low concentrations. Moreover, changes in tadpole activity associated with the pollutants themselves were non-significant, indicating no toxic effect. Alteration of the natural chemical environment of aquatic systems by pollutants may be an important contributing cause for declines in amphibian populations, even at sublethal concentrations.

International audience; Patella ferruginea is a giant patellid limpet endemic to the Mediterranean Sea. It presently is in danger of extinction, and many have called for developing conservation measures including the mass production of spats for re-introduction projects. However, so far all attempts have been relatively unsuccessful. Previous work analyzing the effects of gamma-aminobutyric acid (GABA) on the recruitment of patellid limpets has shown that larvae respond to the presence of this signaling molecule. This response could explain the gregarious distribution typical of this species. In the present study, we demonstrated that GABA is naturally secreted by P. ferruginea in the pedal mucus. GABA is preferentially secreted during the summer, coinciding with the reproductive resting period of the species. Further research should aim to analyze the effects of GABA on larval development and metamorphosis in order to assess its potential use to improve conservation efforts.

International audience; When fish larvae recruit back to a reef, chemical cues are often used to find suitable habitat or to find juvenile or adult conspecifics. We tested if the chemical information used by larvae was intentionally produced by juvenile and adult conspecifics already on the reef (communication process) or whether the cues used result from normal biochemical processes with no active involvement by conspecifics (“spying” behavior by larvae). Conspecific chemical cues attracted the majority of larvae (four out of the seven species tested); although while some species were equally attracted to cues from adults and juveniles (Chromis viridis, Apogon novemfasciatus), two exhibited greater sensitivity to adult cues (Pomacentrus pavo, Dascyllus aruanus). Our results indicate also that spying cues are those most commonly used by settling fishes (C. viridis, P. pavo, A. novemfasciatus). Only one species (D. aruanus) preferred the odour of conspecifics that had had visual contact with larvae (communication).

One of the greatest remaining problems in the field of sex allocation is the variation across species of the extent to which individuals adjust their offspring sex ratio or sex allocation according to environmental conditions. Particularly in the field of sex allocation, there is a lack of research on the mechanisms and cues involved. We address this problem in the outcrossing simultaneous hermaphroditic polychaete Ophryotrocha diadema, which shifts sex allocation by suppressing the female function in the presence of reproductive competitors or multiple partners. We document that O. diadema hermaphrodites can evaluate group size by means of a species-specific chemical released by mature individuals in water. The perception of such a water-borne signal is sufficient to trigger the observed shift in sex allocation, i.e., a suppression of the female function, irrespective of the frequency of encounters with conspecifics. Under natural conditions, such a pheromone will favor partners' encounters and the adjustment of individual sex allocation according to the numbers of reproductive competitors and/or potential partners. Copyright 2006.

A number of recent articles have investigated the potential of familiarity preferences to influence group membership in free-ranging animals. However, it is not clear to which extent individual recognition or a more general recognition of a group odor is responsible for familiarity preferences. First, we tested the sensory basis of the recognition of familiars in stickleback. When allowed to choose between a familiar and a nonfamiliar stimulus shoal on the basis of both visual and chemical communication, visual communication only, and chemical communication only, the preference of focal fish for familiars was shown to depend on the presence of chemical cues. We subsequently investigated the effects of recent habitat and diet on shoaling preferences in the three-spined stickleback (Gasterosteus aculeatus). Experimental fish were divided into four treatment groups consisting of two water treatments (saline and freshwater) and two diet treatments (Daphnia spp. and bloodworm). Focal fish subsequently showed significant association preferences for groups of nonfamiliar fish that had undergone the same water or diet treatment as themselves. These data indicate that individual recognition is not a prerequisite for the expression of association preferences. Copyright 2004.

Operational sex ratio (OSR) has been traditionally thought of as a force imposing competition for mates rather than also a cue used to regulate the intrasexual competition individuals encounter. To assess whether eastern red-spotted newts, Notophthalmus viridescens, could appropriately compare OSRs, we quantified field responses to traps containing four males, a sexually receptive female, four males plus a female, or nothing as a control. Early in the breeding season, males from two populations chose competitive mating opportunities over no mating opportunity at all, but generally preferred less competitive mating prospects. Later in the breeding season, as the OSR of newt populations becomes more male biased, males accordingly increased their acceptance of intrasexual competition. Females avoided groups of four males, and for both sexes, avoidance of male-biased courting groups increased their probability of amplexus courtship. We then isolated an approximately 33-kD protein from male cloacal glands that was used by males to compare OSRs. To our knowledge, this protein represents the first isolated and characterized component of an olfactory cue used to evaluate OSR. These results support two important principles regarding mating systems: (1) OSR can somewhat paradoxically be both the source imposing competition for mates and the source used to reduce it, and (2) analogous to the sex in short supply often being "choosy" selecting mates, the sex in excess (here, males) appears to be choosy about its acceptance of intrasexual competition. Copyright 2005.

The behaviour exhibited by the hermit crab Pagurus longicarpus in response to an empty shell varied in the presence of cues from conspecific individuals according to its familiarity or not with them. This binary discrimination was independent of the conspecific's relative size and was based on chemical signatures, an ability that this species shares with a few other aquatic invertebrates. From our results, olfaction appeared to be the dominant sensory channel in P. longicarpus' binary discrimination, but the combination of two signal components from visual and olfactory channels resulted in the enhancement of the response displayed by the receiver. Besides, crabs reacted differently when exposed to their own odour than to the odour of familiar (as well as unfamiliar) conspecifics, suggesting that recognition in this species can be more refined than a binary discrimination and that chemical ‘badges’ may be attributes of individual crabs.

Burying beetles use small vertebrate carcasses as food for their larvae and defend these carcasses against intra- and interspecific competitors. Breeding associations on carcasses can consist of single females, heterosexual pairs, or various combinations of males and females. When a heterosexual pair collaborate in a breeding attempt, they do not typically exhibit aggressive behavior toward each other, but do attack newly arrived conspecifics that attempt to usurp the carcass. We investigated the cues involved in discrimination between breeding partners and intruders by female burying beetles. We found that resident females tolerate males that have cared for a brood, as well as males that have not cared for a brood but have been on a carcass for a day or two. Males that have had no prior contact with a carcass are attacked. Females appear to use a chemical cue, the "breeder's badge," an apolar substance on the male's cuticle that can be removed by washing with pentane. This cue is reliably correlated with recent male experience with a carcass that is suitable for reproduction. The breeder's badge develops as a result of prolonged contact with such a carcass, and disappears on removal from the carcass; its presence does not require contact with a female or with larvae. Female recognition of their male partners in burying beetles thus does not involve individual recognition, but rather recognition of reproductive condition. Copyright 2003.

Accepted 22 August 2014, published online 30 September 2014, Chelonians are very promising models to explore the role of chemical communication in social contexts. However, it still remains unknown how chemical signals may influence most behavioural patterns in turtles. In this study, we examined whether juvenile yellow-spotted river turtles (Podocnemis unifilis) use chemical cues released into water by other conspecifics to orientate towards them. To test our hypothesis, we compared the behavioural response (i.e., activity level and latency time) of juveniles when exposed to chemical stimuli obtained from other conspecifics (i.e., other juveniles and adult females), as compared to their response in clean water (i.e., the baseline). The results obtained in the study showed that juvenile P. unifilis increased their activity in response to chemical cues of female adult conspecifics. These findings suggest that juvenile turtles may chemically orientate themselves towards adult females during migratory processes. Efficient detection of conspecific chemical cues by juveniles is necessary for particular individuals to aggregate before migrating to habitats with more abundant food resources. Our study provides a framework for future research that should disentangle the role of chemical cues in mass migration of freshwater turtles., Financial support was provided by a FPI grant (reference: BES-2009-025228) and a short stay (ref: EEBB-I-12-04293) to A.I.

Prey naiveté has been hypothesized to be one of the major driving forces behind population declines following the introduction of novel predators or release of inexperienced prey into predator rich environments. In these cases, naïve prey may lack sufficient antipredator behavior and, as a result, suffer increased mortality. Despite this, some evidence suggests that many prey utilize a generalized response to predators. Here, the naiveté hypothesis is tested using a predator-prey pair sharing an evolutionary history: the red swamp crayfish (Procambarus clarkii Girard, 1852) and largemouth bass (Micropterus salmoides Lacépède, 1802). Using farm-reared, naïve crayfish and wild-caught, experienced individuals, laboratory experiments demonstrated that naïve, farmed crayfish lack behavioral responses to chemical cues from bass, both in terms of movement and use of structural refuge. In contrast, experienced crayfish responded strongly to the same cues. In a subsequent field tethering experiment, these naïve individuals suffered a three-fold increase in predation rate. Based on these results, recognition of predators may not be innate in all prey, and previous experience and learning likely play a key role in the development of antipredator behavior.

Benthic conspecific cues are used by competent larvae of many marine invertebrates to locate and settle on suitable habitat. However, aggregations of conspecifics can generate strong intraspecific competition and inter-cohort cannibalism. We investigated the effects of adult conspecific cues on general fitness parameters of juvenile Carcinus maenas (stages J1–J5), and used geometric morphometrics to investigate patterns of allometric growth indicative of life-history strategies and resource use potential. Cues induced faster metamorphosis and slightly shortened intermolt time in J2 individuals, at the expense of acute mortality in J1 crabs. These effects are cumulative but compensatory processes nullify differences by the end of the experiment. Allometric carapace change toward the adult standard remained unchanged, but conspecific cues induced first a change in size (J1) and then in shape (J5) of claws. In both control and cued juveniles, heterochely was incipient but apparent in J5 crabs. Independently of body side, conspecific cues triggered a very marked increase of the propodus posterior margin, presumably enhancing general strength. Therefore, early benthic stages may grow slightly faster to a size refuge, and develop stronger claws providing competitive advantage for the use of high-value food items when population density-dependent processes are more probable.

Alien predators are one of the major causes for rapid decline and extinction of native species, because they often create novel ecological contexts in which the antipredatory responses of native organisms are no longer fit. Although larval amphibians are often capable of innately responding to chemical cues from local predators through changes in morphology and behaviour, naïve tadpoles generally cannot recognize introduced predators with which they have not shared an evolutionary past. However, in a few documented cases, aquatic organisms have been observed to alter morphology or behaviour in response to alien predators. Such a response may have evolved as adaptive recognition, increasing their repertoire of innate responses to include the novel predator or may have evolved as the prey's ability to learn new threats by association with conspecific alarm cues. The red swamp crayfish, Procambarus clarkii, is a harmful invasive species in aquatic systems world-wide, causing great ecological impact on native amphibian populations during the last decades through intense predation of eggs and tadpoles. We demonstrate that naïve tadpoles of the western spadefoot toad, Pelobates cultripes, are not capable of innately recognizing water-borne predator cues from the red swamp crayfish. Nevertheless, we demonstrate that P. cultripes tadpoles can learn to recognize the cues of the invasive predatory crayfish as a threat when they are exposed to predator cues combined with conspecific alarm cues. Finally, we show that tadpoles conditioned by joint exposure to crayfish and alarm cues enjoy higher survival during predation trials with invasive crayfish. Learning to recognize a newly introduced predator through association with conspecific alarm cues may allow successful generalization of antipredatory responses by tadpoles. This cognitive ability of tadpoles may contribute to reduce their vulnerability to alien predators and soothe the impact of invasions in natural populations

An increasing number of studies have documented that sublethal pesticide exposure can change predator-prey interactions. Most of these studies have focused on effects of long-term pesticide exposure on only one type of antipredator traits and have not directly linked changes in these traits to mortality by predation. To get a better mechanistic understanding of how short-term pesticide pulses make prey organisms more vulnerable to predation, we studied effects of 24 h exposure to a sublethal concentration of the insecticide endosulfan and the herbicide Roundup on the major antipredator traits and the resulting mortality by predation in larvae of the damselfly Enallagma cyathigerum. A pulse of both pesticides affected antipredator traits involved in avoiding detection by predators as well as traits involved in escape after detection. After a pesticide pulse, larvae increased activity levels and even further increased the number of walks when predation risk was present. Further, an endosulfan pulse tended to reduce escape swimming speed. In contrast, previous exposure to Roundup caused the larvae to swim faster, yet less often when attacked. Importantly, although both studied pesticides induced maladaptive changes in overall activity, only for endosulfan this resulted in an increased mortality by predation. Our study highlights that considering changed predator-prey interactions may improve ecological risk evaluations of short pesticide pulses, yet also underscores the need (1) to consider effects on all important antipredator traits of the prey as trait compensation may occur and (2) to effectively score the outcome of predator-prey interactions in staged encounters. (C) 2012 Elsevier B.V. All rights reserved. ispartof: Aquatic Toxicology vol:110 pages:91-98 ispartof: location:Netherlands status: published

Predation risk is one of the major forces affecting phenotypic variation among and within animal populations. While fixed anti-predator morphologies are favoured when predation level is consistently high, plastic morphological responses are advantageous when predation risk is changing temporarily, spatially, or qualitatively. Three-spined sticklebacks (Gasterosteus aculeatus) are well known for their substantial variability in morphology, including defensive traits. Part of this variation might be due to phenotypic plasticity. However, little is known about sticklebacks' plastic ability to react morphologically to changing risks of predation and about the proximate cues involved. Using a split-clutch design we show that odour of a predatory fish induces morphological changes in sticklebacks. Under predation risk, i.e., when exposed to odour of a predator, fish grew faster and developed a different morphology, compared to fish reared under low predation risk, i.e., exposed to odour of a non-predatory fish, or in a fish-free environment. However, fast growing comes at cost of increased body asymmetries suggesting developmental constraints. The results indicate that sticklebacks are able to distinguish between predatory and non-predatory fishes by olfactory cues alone. As fishes were fed on invertebrates, this reaction was not induced by chemical cues of digested conspecifics, but rather by predator cues themselves. Further, the results show that variation in body morphology in sticklebacks has not only a strong genetical component, but is also based on plastic responses to different environments, in our case different predation pressures, thus opening new questions for this model species in ecology and evolution.

Few studies have addressed how chemosensation may be impaired by chemical alterations of the environment and anthropogenic disturbance. Humic acid (HA) is a pervasive, naturally occurring organic derivative found in aquatic and terrestrial environments; human activity, however, can lead to elevated levels of HA. Recent studies suggest that environments that contain high levels of HA may hinder chemical communication. We tested the ability of adult zebrafish (Danio rerio) to discriminate between conspecific and heterospecific urinary chemical cues found in the presence and absence of HA. We show that high humic acid levels (200 mg/l) can impair the ability to differentiate conspecifics from heterospecifics. We also found that zebrafish prefer untreated water over HA-treated water. These findings suggest that, in addition to human-produced synthetic compounds, changes in the abundance of naturally occurring substances may also negatively impact natural behaviors in aquatic species by disturbing the sensory environment.

Individual recognition, i.e., the ability of an animal to recognize the identity of a conspecific, is a key element in the social life of many vertebrates. This phenomenon has rarely been investigated in invertebrates, particularly in pre-social arthropods, and is generally poorly understood for several reasons, including (1) the disparity between what the experiments actually demonstrated and what we implicitly mean by individual recognition, (2) the limited knowledge of the sensory channels used to recognize the social partner (particularly in the case of pre-social arthropods), and (3) the general disregard for the nature of representations that an animal constructs concerning the recognized conspecific. This article aims to review what is currently known about individual recognition mediated by pheromones in the shallow-water hermit crab Pagurus longicarpus. Methodological biases, on one hand, and promises of future success, on the other, are pinpointed while explaining the results obtained so far. Fi...

The responses of individuals of the crayfish Orconectes virilis to the same set of chemical cues were tested under flow (lotic) and non-flow (lentic) conditions. The cues presented to the crayfish were food cues, alarm (= crushed conspecifics) cues, and the combination of food + alarm cues. Crayfish behavior (time in burrows) and posture (lowered posture) were significantly affected by the odor treatment, the flow environment, and an interaction of treatment and environment. While the general patterns of responses to odors (more time spent feeding when food cues were introduced, and more time spent in lowered posture and in burrow when alarm cues were introduced) were qualitatively similar in the two environments, responses were stronger (especially to food odors) in the environment with flow. However, the different strength of these responses seemed not to be related to the directional information provided by the flow but rather was probably the effect of a difference in crayfish behavior betwee...