Absence Of Conspecifics Research Articles

The number of syllables in Chernobyl cuckoo calls reliably indicate habitat, soil and radiation levels

Cuckoos Cuculus canorus produce calls that consist of a repeated but variable number of syllables that has given name to the species and the family. Here we tested the hypothesis that cuckoo calls are reliable indicators of environmental and individual quality by determining the number of repeated ‘cuckoo’ syllables in calls in relation to habitat and soil, ionizing radiation, presence of a female cuckoo and local density of male cuckoos at Chernobyl, Ukraine. Males were consistent in their production of syllables, producing more syllables per call when a female or another male arrived. This increase in the number of syllables was larger in males that already produced many syllables in the absence of conspecifics, implying that males of superior quality were still able to increase the number of syllables. Males produced more syllables per call in habitats with black soil and in forests. Furthermore, they produced fewer and more aberrant syllables in radioactively contaminated areas of Chernobyl providing evidence of an effect of environmental perturbation on the number of syllables. These findings are consistent with the hypothesis that the number of syllables is a condition-dependent signal used for attracting mates, repelling competitors, providing information about local environmental conditions for other cuckoos, but also for humans and thus can be used by humans to infer habitat quality.

In Vitro Insemination of the Microphallid Digenean Gynaecotyla adunca.

In vitro cultivation of adult digeneans can benefit research on their biology and contribute to the development of new drugs and vaccines. Successful in vitro growth of excysted metacercariae into adults capable of producing embryonated eggs typically requires that the worms be inseminated. The goal of the study was to develop an in vitro insemination procedure for the progenetic microphallid digenean Gynaecotyla adunca. To do so, we determined the length of time needed for in vitro sperm development in excysted metacercariae and whether the adult worms could self-inseminate in the absence of conspecifics. We also examined the effect of different culture vessels, worm densities, incubation temperatures, length of time incubated with conspecifics, and different pH levels on the percentage of worms inseminated. We found that sperm maturation time for G. adunca was 8-10 hr postexcystment. In the absence of conspecifics, the parasite did not self-inseminate. We observed the highest percentage of inseminated worms when 50 excysted metacercariae were incubated at 37 C for 48 hr in 15-ml conical-bottom tubes containing pH 7 Hank's balanced salt solution. Furthermore, freshly excysted worms incubated in these conditions and then transferred to culture in Dulbecco's modified Eagle medium/F-12 medium and horse serum deposited normal-shaped, embryonated eggs. Our findings provide the basis for a straightforward, reproducible procedure that permits the in vitro insemination of the parasite G. adunca and should be applicable to other progenetic digeneans.

Caching in the presence of competitors: Are Cape ground squirrels (Xerus inauris) sensitive to audience attentiveness?

When social animals cache food close to their burrow, the potential for an audience member to observe the event is significantly increased. As a consequence, in order to reduce theft it may be advantageous for animals to be sensitive to certain audience cues, such as whether they are attentive or not to the cache event. In this study, observations were made on three groups of Cape ground squirrels (Xerus inauris) in their natural habitat when they cached provisioned food items. When individuals cached within 10m of conspecifics, we recorded the attentiveness (i.e. whether any audience members were orientated towards the cacher, had direct line of site and were not engaged in other activities) and identity of audience members. Overall, there was a preference to cache when audience members were inattentive rather than attentive. Additionally, we found rank effects related to cache avoidance whereby high-ranked individuals showed less avoidance to cache when audience members were attentive compared to medium- and low-ranked individuals. We suggest this audience sensitivity may have evolved in response to the difference in competitive ability amongst the ranks in how successful individuals are at winning foraging competitions. This study demonstrates that Cape ground squirrels have the ability to not only monitor the presence or absence of conspecifics but also discriminate individuals on the basis of their attentive state.

Social Context Modulates Predator Evasion Strategy In Guppies

AbstractSocial context is a powerful mediator of behavioral decisions across animal taxa, as the presence of conspecifics comes with both costs and benefits. In risky situations, the safety conferred by the presence of conspecifics can outweigh the costs of competition for resources. How the costs and benefits of grouping influence decisions among alternative antipredator behaviors remains largely unexplored. We took advantage of the Trinidadian guppy (Poecilia reticulata) to examine the influence of social context on alternative behavioral responses to threats. We compared the frequency of active (startle) versus passive (freeze) responses to sudden acoustic stimuli in the presence and absence of conspecifics. We found that fish were relatively less likely to startle and more likely to freeze when in a group than when alone, indicating that immediate social context modulates predator evasion strategy in guppies. We suggest that these social context‐dependent changes reflect trade‐offs between survival and energy expenditure. To our knowledge, an effect of immediate social environment on startle probability has not been previously demonstrated in a teleost.

Sociality modulates the effects of ethanol in zebra fish.

The complex social behavior exhibited by zebra fish is often leveraged in preclinical studies to investigate whether and how psychoactive compounds modulate inter individual interactions. Due to theoretical and methodological constraints, previous studies on the effects of ethanol (EtOH) on social behavior focused on homogeneous groups in which all individuals were treated, thereby limiting the possibility of isolating all the intervening variables. To identify how a social group affects the individual response to EtOH, we quantified the behavior of a single treated individual (acute 0.00, 0.25, 0.50, and 1.00% concentration/volume) swimming together with a group of untreated subjects or alone. A novel in-house-developed automated tracking system was utilized to extract the trajectories of each subject and analyze individual and social behavior. Specifically, we characterized the locomotion of each individual, the cohesion and degree of alignment of the group of untreated subjects, and the interaction between treated and untreated subjects. Individual response to high EtOH concentrations varied depending on the presence or absence of conspecifics. Specifically, EtOH-exposed subjects swam faster when group-tested than in isolation. Remarkably, the presence of the exposed individual substantially influenced the behavior of the untreated subjects. Thus, untreated subjects swam faster when the treated individual was exposed to intermediate EtOH concentrations, without varying their cohesion and degree of alignment. No change in the distance between treated and untreated subjects was found; however, the likelihood that the swimming direction of the treated individual anticipated the response of the group was influenced by EtOH concentration. Our results demonstrate the feasibility of exposing a single individual to EtOH and test it together with untreated subjects. This approach has the potential to unravel the social determinants of individual response to alcohol, by enabling us to dissociate EtOH exposure from sociality.

The Influence of Social Environment: Behavior of Unrelated Adults Affects Future Juvenile Behaviors

AbstractJuveniles' behaviors are often influenced by the behaviors of conspecifics. Most experimental studies of the influence of conspecific behavior vary the social environment by the presence or absence of conspecifics or investigate the impact of the outcome of social encounters (winner/loser effects) but less frequently expose individuals to variation in behavioral phenotypes present in the social environment. Based on previous work showing that juveniles of the salamander Plethodon cinereus are likely to interact frequently with non‐parental adults, I hypothesized that territorial adults in the social environment alter the future behaviors of juveniles. I measured the intracohort social behaviors of juvenile salamanders collected from two geographic areas, Michigan (MI) and Virginia (VA), before and after housing with ostensibly territorial (VA) or non‐territorial (MI) adults. There were overall effects of adult territoriality and aggression on the behavior of juveniles. However, juveniles from populations in MI were especially susceptible to behavioral modification. Compared with behaviors prior to being housed with adults, MI juveniles increased investigatory and escape behaviors in juvenile–juvenile interactions after being housed with adults that displayed territorial behaviors and decreased investigatory and escape behaviors after being housed with non‐territorial adults. This study shows that not only is a specific behavior, territoriality of adult salamanders, a social environment that modifies future juvenile behaviors, but the effects of social environment may differ between populations.

Coral reef fish incorporate multiple sources of visual and chemical information to mediate predation risk

Behavioural ecology is rife with examples of the way in which prey animals make decisions to alter when, where and how they forage or reproduce in response to variation in predation risk. Given that animals cannot have perfectly accurate information regarding the relative costs and benefits of each decision made, the process of decision making is fraught with uncertainty, particularly given that different sources of information will have different levels of risk associated with them. The consequence of ignoring accurate predator information is potentially death; therefore animals should have evolved the ability to incorporate multiple sources of information, extract important components from each source and respond accordingly. In this study, the anemonefish, Amphiprion percula, responded with antipredator behaviour to damage-released chemical cues from conspecifics and congenerics. However, the visual cues provided by the presence or absence of conspecifics and congenerics dramatically influenced the way in which individuals responded to chemical indicators of risk. Our results suggest that anemonefish have a complex decision-making process that incorporates multiple sources of information each with different degrees of uncertainty.

No honor among snails: Conspecific competition leads to incomplete drill holes by a naticid gastropod

Incomplete drill holes in shelled invertebrate prey produced by predatory gastropods are often interpreted as failed attacks, and the frequency of incomplete drill holes in a sample is thought to provide insight into the effectiveness of prey defensive adaptations. Here, we conduct an experimental test of the hypothesis that differences in the frequencies of incomplete drill holes do not necessarily indicate anything about the prey and can instead be triggered by disturbance competition among conspecific drilling gastropods. Our test employed the western Atlantic naticid gastropod Neverita delessertiana and its venerid bivalve prey Chione elevata. The experiment consisted of an isolation treatment, where predators fed in the absence of conspecifics, and a competition treatment, where predators fed in groups of three. Competitive interactions, which included grappling, prey theft, and cannibalism, were found to be important in determining the presence of incomplete drill holes, as this trace was absent in the isolation treatment but present in the competition treatment, with the frequency of incomplete drill holes increasing in interactions among larger gastropods. These results suggest that interpretations of both field and fossil data must consider the role of competitive disruption as an additional mechanism underlying long-term patterns in the frequency of incomplete drill holes in the fossil record.

Effects of Conspecifics on Feeder Choice by Northern Cardinals

Inter- and intra-specific competition are known to influence feeding decisions, but relatively little research has investigated how inter- and intra-sexual interactions can impact foraging. We studied foraging preferences of male and female Northern Cardinals (Cardinalis cardinalis) during winter and found they preferred sunflower seed to safflower seed when presented with paired feeders in the absence of conspecifics. Male cardinals avoided feeders occupied by other males and approached feeders occupied by females, regardless of feeder contents. Female cardinals avoided other females and especially males when choosing feeders. These changes in foraging behavior by male and female cardinals as a result of conspecific presence indicate inter- and intra-sexual interactions alter the attractiveness of a high or low energy food source.

The effect of isolation from conspecifics on spermatophore output of two species of eriophyoid mites

Eriophyoids are group-living, phytophagous mites whose males place spermatophores on a substrate, while females seek them out and perform self-insemination. Various factors, for example, rainfall, extreme temperatures and predatory mites, can considerably reduce the population size of eriophyoids which, simultaneously, may influence their reproductive strategies and output. In this study, the effect of a relatively short, 2-day absence of conspecifics on the spermatophore production of Aculus fockeui (Nalepa & Trouessart) and Aculops allotrichus (Nalepa) was examined. These species differ in male reproductive strategies. Both A. allotrichus and A. fockeui males can deposit spermatophores in the absence of quiescent female nymphs (QFNs). However, when QFNs are present, A. allotrichus males guard the nymphs from other males and deposit spermatophores beside them. In contrast, male A. fockeui rarely deposit spermatophores beside QFNs and do not interact with competitors. Previous tests have revealed that spermatophore output of eriophyoid males kept in isolation can differ significantly from output in the presence of conspecifics. In this study, on the second day of isolation, males of A. allotrichus significantly increased their rate of spermatophore deposition, whereas the coefficient of variation (CV) for spermatophore output considerably decreased. In A. fockeui, in contrast, both parameters were similar on both days. Moreover, no matter how many spermatophores the males of A. fockeui deposited on the first day, they produced a similarly high or low number on the second day (positive correlation between the two days). However, if on the first day male A. allotrichus deposited a relatively high number of spermatophores, on the second day they produced a relatively low number, or vice versa (negative correlation). All inter-specific discrepancies in spermatophore deposition during the absence of conspecifics are discussed in the context of differences in male reproductive strategies, as well as possible differences in male energy budgets and rhythms of spermatophore deposition between species.

Visual and chemical cues in habitat selection of sepioid larvae

The present study explored, by experiments in aquaria, the modality of senses used by sepioid larvae ( Euprymna scolopes) when searching for their species’ settlement habitat (Rangiroa, French Polynesia). Our results showed that E. scolopes larvae made active choices among the four habitats tested (living coral, dead coral, macroalgae and sand), and that their selective choice was influenced by presence or absence of conspecifics on the habitat. Sensory experiments showed that E. scolopes larvae differentiated between conspecifics and heterospecifics (and not between their preferred habitat versus the least preferred habitat) using both visual and olfactory cues. Overall, our results suggest species-specific cues may play a vital role in establishment spatial patterns at settlement.

Effect of conspecifics density on the settlement of Petrolisthes laevigatus (Decapoda: Porcellanidae)

Settlement is one of the critical points in the development of organisms with complex life cycles. Some marine invertebrates respond to specific cues such as substratum and conspecifics, and the larvae of species presenting gregarious settlement are characterized by a preference for settlement in patches with conspecifics over those without. An evaluation was made in the field of the effect of conspecifics density on the settlement of Petrolisthes laevigatus during two settlement seasons. The size-distribution and density were maintained constant throughout the first settlement season, while in the second year they were adjusted to match those presented in three previously identified periods during the season. The settlement rate of P. laevigatus was higher in the presence than the absence of conspecifics. There was evidence of saturation in the settlement of the higher densities, mainly at the beginning of the settlement season, when approximately 80% of the settlement occurred. We propose that gregarious settlement is an important factor in determining the distribution and abundance of P. laevigatus at different spatial scales, both within and among coastal areas, and could restrict the colonization of new areas and the recovery of populations reduced by disturbances.

Post-weaning chronic social isolation produces profound behavioral dysregulation with decreases in prefrontal cortex synaptic-associated protein expression in female rats

Early life stressors in rodents, including maternal separation and social isolation, have been shown to disrupt brain development and profoundly affect a wide-range of behaviors in adult animals. In this study, we focus on the development of female Sprague–Dawley rats in the presence and absence of conspecifics during the critical period of social play. Similar studies in male rodents have shown that this form of social deprivation results in dysregulated dopaminergic and serotonergic functions in the brain with core features of neuropsychiatric disorders including anxiety disorder and schizophrenia. Here we examined the behavioral and biochemical effects of post-weaning social isolation in female rats. Our findings demonstrated that isolation rearing produced marked deficits in social interaction behaviors and increased anxiety in open-field and novelty-suppressed feeding tests. The expression of synaptic-associated proteins PSD95 and synapsin I as well as glutamate receptors subunits GluR1 and NR1 in the prefrontal cortex (PFC) were significantly reduced in isolation-reared female rats. Current findings provide evidence that in female rats, post-weaning environmental disruption can result in profound dysregulation of synapse-related proteins and behavior.

Optimization of Culture Conditions for In Vitro Fertilization and Reproduction of Microphallus turgidus (Trematoda: Microphallidae)

Most attempts to culture adult digeneans in vitro are unsuccessful. Even progenetic digeneans typically fail to produce infective eggs in axenic culture. However, metacercariae of Microphallus turgidus grown in vitro mature into adults and release eggs infective to the hydrobiid snail Spurwinkia salsa. The objectives of the present study were to verify the reproducibility of the M. turgidus culture protocol, to define optimal culture conditions for M. turgidus further, and to investigate why the parasite can be grown successfully in the absence of the definitive host. In the original cultivation protocol, excysted M. turgidus metacercariae from grass shrimp (Palaemonetes pugio) were incubated overnight in a conical-bottom centrifuge tube containing Hank's balanced salt solution and then cultivated in flat-bottom culture plate wells containing RPMI-1640 plus 20% horse serum. The gas phase was air. Worms cultured under this protocol consistently deposited eggs infective to snails. Worms grown in anaerobic conditions deposited few eggs, and those cultured in a gas phase of 5% CO(2) survived longer and produced more eggs than those cultured in air. However, snails were less likely to become infected when fed eggs deposited by worms cultured in 5% CO(2). Additionally, worms incubated with conspecifics in conical-bottom tubes prior to cultivation were more likely to be inseminated than worms incubated in flat-bottom culture wells; the highest percentages of inseminated worms occurred when metacercariae were incubated 24 hr in conical-bottom tubes at a density of 50 worms/tube and at a temperature of 37 C. Worms incubated in the absence of conspecifics were not fertilized and failed to produce infective eggs.

Synergistic effects of habitat preference and gregarious behaviour on habitat use in coral reef cardinalfish

Spatial distributions of coral reef fish species are potentially determined by habitat preferences and behavioural interactions. However, the relative importance of these factors and whether or not behavioural interactions reinforce or disrupt habitat associations are poorly understood. This paper explores the degree to which habitat and social preferences explain the association that three common coral reef cardinalfish species (Zoramia leptacanthus, Archamia zosterophora and Cheilodipterus quinquelineatus; family Apogonidae) have with coral substrata at Lizard Island, Great Barrier Reef. At diurnal resting sites, species were strongly associated with branching corals, with 80–90% of each species inhabiting one branching coral species, Porites cylindrica. Species were also highly gregarious, forming large con-specific and hetero-specific aggregations in coral heads, potentially reinforcing habitat associations. Three-way choice experiments were conducted to test fishes habitat preferences for living coral over dead substrata, for particular coral species, and the influence of gregarious behaviour on these habitat choices. The strength of habitat preferences differed among species, with Z. leptacanthus preferring live coral and P. cylindrica, A. zosterophora preferring P. cylindrica, whether live or dead and C. quinquelineatus exhibiting no preferences. All species were attracted to conspecifics, and for C. quinquelineatus and A. zosterophora, conspecific attraction resulted in stronger preferences for live corals. Gregarious behaviour also increased C. quinquelineatus associations with P. cylindrica. The relative strength of social attraction versus habitat preferences was investigated by comparing fish habitat preferences in the presence and/or absence of conspecifics. The presence of conspecifics on non-preferred rubble habitat reduced each species association with live coral. This study’s results indicate that in the field, habitat preferences and conspecific attraction combine to reinforce the association between cardinalfishes and a narrow range of coral substrata.

Multimodal alarm behavior in urban and rural gray squirrels studied by means of observation and a mechanical robot

Abstract Urbanization of animal habitats has the potential to affect the natural communication systems of any species able to survive in the changed environment. Urban animals such as squirrels use multiple signal channels to communicate, but it is unknown how urbanization has affected these behaviors. Multimodal communication, involving more than one sensory modality, can be studied by use of biomimetic mechanical animal models that are designed to simulate the multimodal signals and be presented to animal subjects in the field. In this way the responses to the various signal components can be compared and contrasted to determine whether the multimodal signal is made up of redundant or nonredundant components. In this study, we presented wild gray squirrels in relatively urban and relatively rural habitats in Western Massachusetts with a biomimetic squirrel model that produced tail flags and alarm barks in a variety of combinations. We found that the squirrels responded to each unimodal component on its own, the bark and tail flag, but they responded most to the complete multimodal signal, containing both the acoustic and the moving visual components, providing evidence that in this context the signal components are redundant and that their combination elicits multimodal enhancement. We expanded on the results of Partan et al. (2009) by providing data on signaling behavior in the presence and absence of conspecifics, suggesting that alarm signaling is more likely if conspecifics are present. We found that the squirrels were more active in the urban habitats and that they responded more to tail flagging in the urban habitats as compared to the rural ones, suggesting the interesting possibility of a multimodal shift from reliance on audio to visual signals in noisier more crowded urban habitats.

Conspecific presence affects the physiology and behaviour of developing trout

Interactions between conspecifics during embryonic development have the potential to influence phenotypic traits of individuals, with social interaction being particularly important for the realisation of normal behaviours. Here, the effect of increasing numbers of conspecifics (from isolation to groups of 20, 50, 100 and 200) on the physiology and behaviour of developing trout was investigated with the hypothesis that a) conspecific presence would alter physiological processes and b) that development in the absence of conspecifics would affect subsequent behavioural performance. During development, mass, oxygen consumption, sodium uptake and ammonia excretion rates were measured at a variety of time points from fertilisation to after hatching. After first feeding, behaviour of individuals raised in social isolation was compared to behaviour of juvenile fish raised in social groups. Embryos and larvae raised in social isolation had lower oxygen consumption rates, lower sodium uptake rates and higher ammonia excretion rates compared to those raised in groups. Social isolation delayed the response of a juvenile fish to its own mirror image but did not affect the probability of it winning a paired encounter with an individual raised in a social environment. In conclusion, the presence of conspecifics alters physiological processes during trout embryo and larval development and subsequent social behaviours of juveniles.

Ecological determinants and sensory mechanisms in habitat selection of crustacean postlarvae

Animals use sensory stimuli to assess and select habitats, mates, and food as well as to communicate with other individuals. One of the great mysteries of crustacean ecology is how postlarvae locate the relatively rare patches of coral reef habitat on which they settle. The present study aimed to estimate, by experiments in aquaria and biochemical analysis, the sensory modalities of crustacean postlarvae for senses used in searching for their species' settlement habitat. The study was carried out on 9 crustacean species (Calappa calappa, Pachygrapsus planifrons, Xanthidae sp., Lysiosquillina maculata, L. sulcata, Raoulserenea sp., Stenopus hispidus, Palaemonidae sp., and Panulirus penicillatus). For each species, a cohort of 30 postlarvae was captured on the same night on the reef crest of Rangiroa Atoll (French Polynesia). Among the 9 crustacean species studied, 6 made active habitat choices among the 4 habitats tested (live coral, dead coral, macroalgae, and sand) at the postlarval stage, but the presence or absence of conspecifics on the habitat did not influence their selective choice. Sensory experiments found that 4 species differentiated between their preferred habitat versus another habitat and 2 species differentiated between conspecifics and heterospecifics, using visual and/or olfactory cues. Lastly, the high performance liquid chromatography experiments showed that the 4 habitats and conspecifics (except L. maculata and S. hispidus) tested have different and unique chemical odors. Overall, our study is the first to highlight the sensory modalities for a broad range of crustacean species to detect and move toward settlement habitats and/or conspecifics.

Self-amplification as a source of interindividual variability: Shelter selection in cockroaches

Although group effect and collective decisions have been described in many insect species, the behavioral mechanisms involved in the process remain poorly documented at the individual level. We examined how individual behavior depends on the environmental context and we precisely characterized the behavioral rules leading to settlement of individual cockroaches in resting site. We focused on the spatial and temporal distribution of individuals in absence of conspecifics. Using isolated adult males of the cockroach Periplaneta americana, we showed that the quality of resting sites and the duration of the settlement exerted an influence on the individual decision-making: the probability of leaving a resting site decreased with the time spent under a shelter. A numerical model derived from experimental data suggested that this simple rule of self-amplification can also account for the interindividual variability.

Functions of Bat Social Calls: The Influence of Local Abundance, Interspecific Interactions and Season on the Production of Pipistrelle (Pipistrellus pipistrellus) Type D Social Calls

We studied the social call rate of the common pipistrelle (Pipistrellus pipistrellus) in natural habitats in relation to the presence or absence of conspecifics and of other bat species by acoustical and behavioural monitoring and analyses. The relative frequency of type D social calls increased, when more than one individual of P. pipistrellus was present, compared to one individual. The data confirm the assumption that one function of social calls is repelling conspecifics (food patch defence hypothesis). In the presence of other species of the genus Pipistrellus or of other genera, the mean social call rate did not significantly increase, except when P. pygmaeus was present. Hence, social call production as a food patch defence typically is not significantly influenced by interspecific interactions. This directs to niche separation concerning the foraging mode of different species. The closely related species P. pipistrellus and P. pygmaeus may compete for resources and communicate by type D social calls. Pipistrelles are known to use a series of type D social calls during songflights. For instance, males use this calling behaviour to attract females and repel competing males. During the mating season P. pipistrellus produced social calls more frequently when other pipistrelle species were absent. This shows that interspecific recognition may influence the mating behaviour of P. pipistrellus. Competing for non-food resources like mating roosts may cause bats to keep calm in the presence of other species.