Juvenile Behavior Research Articles

Sensory determinants of agonistic interactions in the red-backed salamander, Plethodon cinereus

Many animals use and react to multimodal signals — signals that occur in more than one sensory modality. This study focused on the respective roles of vision, chemoreception, and their possible interaction in determining agonistic responses of the red-backed salamander, Plethodon cinereus. The use of a computer display allowed separate or combined presentation of visual and chemical cues. A cue isolation experiment using adult male and juvenile salamanders showed that both visual and chemical cues from unfamiliar male conspecifics could increase aggressive displays. Submissive displays were only increased in juveniles, and specifically by the visual cue. The rate of chemoinvestigation of the substrate was increased only by chemical cues in adults, whereas both chemical and visual cues increased this behaviour in juveniles. Chemoinvestigation appears, thus, more dependent on sensory input in juvenile salamanders. A follow-up experiment comparing responses to visual cues of different animals (conspecific salamander, heterospecific salamander and earthworm) or an inanimate object (wood stick) showed that exploratory behaviour was higher in the presence of the inanimate object stimulus. The heterospecific salamander stimulus produced strong submissive and escape responses, while the conspecific salamander stimulus promoted aggressive displays. Finally, the earthworm stimulus increased both aggressive and submissive behaviours at intermediate levels when compared to salamander cues. These specific combinations of agonistic and exploratory responses to each stimulus suggest that salamanders could discriminate the cues visually. This study sheds some light on how information from different sensory modalities guides social behaviour at different life stages in a salamander.

Burrowing, byssus, and biomarkers: behavioral and physiological indicators of sublethal thermal stress in freshwater mussels (Unionidae)

Recent research has elucidated the acute lethal effects of elevated water temperatures to glochidia (larvae), juvenile, and adult life stages of freshwater mussels (Order Unionida), but few studies have focused on sublethal effects of thermal stress. We evaluated the sublethal effects of elevated temperature on burrowing behavior and byssus production in juveniles, and on enzymatic biomarkers of stress in adults in acute (96 h) laboratory experiments in sediment, with two acclimation temperatures (22 and 27 °C) and two experimental water levels (watered and dewatered) as proxies for flow regime. Increasing temperature significantly reduced burrowing in all five species tested, and the dewatered treatment (a proxy for drought conditions) reduced burrowing in all but Amblema plicata. Production of byssal threads was affected most drastically by flow regime, with the probability of byssus presence reduced by 93–99% in the dewatered treatment, compared to the watered treatment (a proxy for low flow conditions); increasing temperature alone reduced byssus by 18–35%. Alanine aminotransferase and aspartate aminotransferase were significantly affected by treatment temperature in the 27 °C acclimation, watered test (p = 0.04 and 0.02, respectively). Our results are important in the context of climate change, because stream temperature and flow are expected to change with increasing air temperature and altered precipitation patterns.

The effect of oil derivatives on the ability of entomopathogenic nematode Steinernema feltiae to find host

Abstract: The aim of the research was to evaluate the effect of oil derivatives on entomopatogenic nematode Steinernema feltiae. The effect of unleaded petrol, diesel oil and used engine oil on the ability of S. feltiae infective juveniles to locate test insect was investigated. The experiments were carried out in laboratory conditions in four replications. In the first experiment the effect of oil derivatives on behavior of infective juveniles on agar medium in the presence of test insects was investigated. Oil derivatives were added to the medium at the rate of : 2000, 4000, 6000 and 8000 mm dm. Infective juveniles did not dispersed towards test insects on agar medium contaminated with oil derivatives. The application of high doses of oil derivatives had also negative effect on nematodes activity and mortality. In the second experiment infective juveniles were applied into contaminated soil. Soil was polluted with following oil derivatives: unleaded petrol, diesel oil and used engine oil at the rate of : 2000, 4000, 6000 i 8000 mg kg. In soil contaminated with oil derivatives test insect mortality was significantly lower than in uncontaminated control. It was also revealed that less extensive infestation of test insects with nematodes was observed in contaminated soil. Reaction of S. feltiae to particular oil derivatives was diverse. The most toxic effect on nematode ability to find host was observed in soil polluted with unleaded petrol. The applied oil derivatives had also an adverse effect on the female/male ratio of nematodes infesting host insect.

Toxicity of Aqueous Extract of Desert Date (Balanites Aegyptiaca Linnaeus) On the Juveniles of Catfish (Clarias Gariepinus Teugels, 1986).

. Abstract: An investigation was conducted on the toxic effects of the fruit extract of (Balanites aegyptiaca L.) on the mortality and behaviour of juveniles of African catfish (Clarias gariepinus). In the acute lethal toxicity study, the fish were exposed to different concentration levels of 64.0, 32.0, 16.0, 08.0, 04.0 and 0.00gL -1 (control) of the fruit extract. A positive correlation (r=0.9811) was observed between fish mortality and the various concentrations used. Prior to death of fish, some behavioural activities observed were erratic swimming on the water surface, loss of reflex and hyperventilation. Haemoglobin estimation and packed cell volume (PCV) values were significant (P< 0.05) for acute lethal toxic dose. The 96h-LC50 value of the fruit extract was obtained as 12.59gL -1 , with lower and upper confidence limits of 7.87gL -1 and 20.14gL -1 respectively. Phytochemical analysis showed that the fruit contained saponins, flavonoids, cardiac glycosides, tannins and carbohydrates. In conclusion, solution of the fruit extract caused fish mortality, and its toxic effects lowered the values of some haematological parameters compared to the control group.

Bottom feeding and net chasing improve foraging behavior in hatchery-reared Japanese flounder Paralichthys olivaceus juveniles for stocking

We examined the effect of bottom feeding and net chasing as means to improve the maladaptive off-bottom swimming of hatchery-reared Japanese flounder Paralichthys olivaceus juveniles for stock enhancement. Three treatments were tested: (1) a bottom feeding treatment in which fish were fed near the bottom; (2) a net chasing treatment in which fish were chased by a hand net two to four times a day, and (3) a surface feeding treatment in which fish were fed from the surface (control treatment). Foraging behavior at the surface with surface feeding was analyzed 1 day before initiating these treatments and 2 weeks thereafter. A comparison of the pre- and post-treatments revealed that off-bottom swimming was less in the bottom feeding treatment and net chasing treatments. A comparison of off-bottom swimming in the bottom feeding treatment between the pre- and post treatments revealed that bottom fed fish showed less off-bottom swimming than surface fed fish. These findings suggest that fish behavior can be manipulated during the rearing period and that such manipulations can be used to improve the behavior of fish for release.

Anxiogenic Effects of Developmental Bisphenol A Exposure Are Associated with Gene Expression Changes in the Juvenile Rat Amygdala and Mitigated by Soy

Early life exposure to Bisphenol A (BPA), a component of polycarbonate plastics and epoxy resins, alters sociosexual behavior in numerous species including humans. The present study focused on the ontogeny of these behavioral effects beginning in adolescence and assessed the underlying molecular changes in the amygdala. We also explored the mitigating potential of a soy-rich diet on these endpoints. Wistar rats were exposed to BPA via drinking water (1 mg/L) from gestation through puberty, and reared on a soy-based or soy-free diet. A group exposed to ethinyl estradiol (50 µg/L) and a soy-free diet was used as a positive estrogenic control. Animals were tested as juveniles or adults for anxiety-like and exploratory behavior. Assessment of serum BPA and genistein (GEN), a soy phytoestrogen, confirmed that internal dose was within a human-relevant range. BPA induced anxiogenic behavior in juveniles and loss of sexual dimorphisms in adult exploratory behavior, but only in the animals reared on the soy-free diet. Expression analysis revealed a suite of genes, including a subset known to mediate sociosexual behavior, associated with BPA-induced juvenile anxiety. Notably, expression of estrogen receptor beta (Esr2) and two melanocortin receptors (Mc3r, Mc4r) were downregulated. Collectively, these results show that behavioral impacts of BPA can manifest during adolescence, but wane in adulthood, and may be mitigated by diet. These data also reveal that, because ERβ and melanocortin receptors are crucial to their function, oxytocin/vasopressin signaling pathways, which have previously been linked to human affective disorders, may underlie these behavioral outcomes.

Migratory patterns of lower Feather River natural and hatchery-origin Oncorhynchus mykiss

Oncorhynchus mykiss are known to exhibit variable life histories expressed under genetic control or through the influence of the environment. Altered environmental conditions and the presence of large numbers of non-indigenous hatchery fish can affect the rate of anadromy observed in California’s Central Valley O. mykiss. The lower Feather River, a large regulated river in Northern California, supports one of the largest populations of O. mykiss in the Central Valley, heavily subsidized by hatchery production. I examined downstream migratory behavior, movement rate, and success of natural-origin juveniles, natural-origin adults, and hatchery-origin fish using acoustic telemetry. I found that all three groups displayed a mix of migratory and non-migratory life histories. Hatchery-origin adults exhibited more migratory behavior (anadromy) than natural-origin juveniles and natural-origin adults, 41 %, 24 %, and 13 % respectively. Downstream migrants were also significantly larger than non-migratory fish. Migration timing was similar among the three groups, but natural-origin juveniles displayed the most rapid rate of movement. The relative success of each group was highest for fish migrating through the Sacramento-San Joaquin Delta to the Pacific Ocean. Hatchery-origin adults migrating through the lower Feather River showed the lowest relative success (33 %). The dominance of non-migratory life histories pattern among lower Feather River O. mykiss may be in response to the suitable habitat provided by hypolimnetic releases below dams and the current hydrological regime within the highly altered Sacramento-San Joaquin watershed.

Influence of extremely low frequency magnetic fields on juvenile development and behaviour in a mouse model

Influence of extremely low frequency magnetic fields on juvenile development and behaviour in a mouse model

Concurrent attenuated reactivity of alpha-amylase and cortisol is related to disruptive behavior in male adolescents

Attenuated reactivity of salivary alpha-amylase has been proposed as a specific sympathetic marker of disruptive behavior in juveniles and may have additional value to studying other autonomic parameters and hypothalamic–pituitary–adrenal axis activity. Investigating the interrelationships between neurobiological parameters in relation to juvenile disruptive behavior may enhance insight into the complex mechanisms at play.We investigated salivary alpha-amylase, cortisol, heart rate (HR), and heart rate variability (HRV) in response to a standardized public speaking task, and examined interactions between these parameters in relation to disruptive behavior. Participants were 48 delinquent male adolescents (mean age 18.4years, SD 0.9), with and without a disruptive behavior disorder (resp. DP+, DP−) and 16 matched normal controls (NC). A structured psychiatric interview as well as the Youth Self Report and Child Behavior Checklist were administered to assess disruptive behavior.Alpha-amylase and cortisol reactivity, but not HR or HRV, showed significant inverse associations with dimensional measures of disruptive behavior. Moreover, both cortisol and alpha-amylase reactivity were significantly lower in the DP+ group as compared to the NC group. The mentioned relationships remained present when nicotine use was entered as a covariate. Combining alpha-amylase and cortisol in one model explained a larger part of the variance of disruptive behavior than either single parameter. There were no interactions between alpha-amylase and cortisol or HRV in relation to disruptive behavior.Attenuated alpha-amylase responsivity to stress is a correlate of disruptive behavior in late-adolescent males. Although nicotine use explains a considerable part of the variance of disruptive behavior, both alpha-amylase and cortisol are related to disruptive behavior, over and above the effect of nicotine use. Combining alpha-amylase and cortisol improved insight into neurobiological mechanisms involved with disruptive behavior; concurrent low reactivity of both parameters was related to higher levels of disruptive behavior.

Ontogenetic variation in site fidelity and homing behaviour of a temperate reef fish

Animals vary in their level of site fidelity and ability (or motivation) to return to a home site when displaced. Homing behaviour may be advantageous when the costs (e.g., associated with traversing a potentially hostile landscape) are outweighed by the collective benefits (e.g., access to resources and stable social interactions) of returning to a home site. Here, we hypothesise that these costs relative to benefits — and hence, propensity to home when displaced — will vary among ontogenetic stages of a small reef fish (the common triplefin, Forsterygion lapillum) in New Zealand. We evaluated site fidelity and homing behaviour of three distinct stages (settlers, juveniles, and adults) of F. lapillum, using experimental displacements of tagged individuals. Settlers use different habitats (canopies of macroalgae) than those used by juveniles and adults (cobbles on the seafloor). To evaluate site fidelity of settlers, we constructed an array of “artificial canopies” at 5m intervals along two parallel transects separated by 100m of reef. We allowed fish to settle naturally to these artificial canopies, then tagged them with elastomer, and returned them to these structures (either to the same artificial canopy or else displaced to another canopy 100m distant). After ~20days, we re-captured ~30% of tagged fish, and of these, none had returned to a home canopy when displaced (indeed, we documented no movement of tagged fish between any of the artificial canopies). We evaluated site fidelity and homing behaviour of older juveniles and adults using a separate experimental translocation of tagged individuals. For this experiment, we collected juveniles and adults from a common site, tagged them with elastomer, and either returned them to their home site or else translocated them different distances (up to 800m) away from their home site. We found that adults were more likely to return to their home site when displaced ≤200m, and juveniles were more likely to remain at release locations. Overall, our results suggest that site fidelity and an ability to successfully return to a home site vary with ontogenetic stage. These findings have implications for intraspecific interactions, and indicate that local site quality may be important for adult stages of the common triplefin.

Prevalence of traumatic brain injury in juvenile offenders: A meta-analysis

Studies of traumatic brain injury (TBI) among adult populations demonstrate that such injuries can lead to aggressive behaviors. Related findings suggest that incarcerated individuals have high rates of brain injuries. Such studies suggest that traumatic brain injury may be related to the etiology and recidivism of criminal behavior. Relatively few studies have examined the prevalence of TBI using a delinquent juvenile sample. In order to assess the relationship between TBI and juvenile offender status, the current study used meta-analytic techniques to examine the odds of having a TBI among juvenile offenders. Across 9 studies, we found that approximately 30% of juvenile offenders have sustained a previous brain injury. Across 5 studies that used a control group, a calculated summary odds ratio of 3.37 suggests that juvenile offenders are significantly more likely to have a TBI compared to controls. Results suggest that the rate of TBIs within the juvenile offender population is significant and that there may be a relationship between TBIs and juvenile criminal behavior.

Evading invaders: the effectiveness of a behavioral response acquired through lifetime exposure

Abstract Understanding the mechanisms driving adaptations to survive agonistic interactions, and their function, provides insight into how native species adapt to aggressive invaders, a growing global threat. We staged encounters between native fence lizards (Sceloporus undulatus) and red imported fire ants (Solenopsis invicta) on and off the ant mound (nest) to examine the effectiveness of lizard antipredator behavior through ontogeny while focusing on the impact of lifetime and evolutionary exposure to this invasive threat. We used field-caught and lab-reared lizards from a fire ant–invaded and an uninvaded site. In ∼90% of cases, fire ants found lizards within 12 min in natural lizard habitat. Lizards that performed rapid twitches of their body and/or fled after initial encounter with a fire ant scout reduced their risk of having additional fire ants recruit to the attack. The majority of lizards that had been exposed to fire ants within their lifetime (field-caught lizards from the invaded site) behaviorally responded to attack, whereas relatively few lizards that were naïve to fire ants (all lab-reared lizards and field-caught lizards from the uninvaded site) responded. Because fewer adult lizards responded to fire ants than juveniles, they were recruited to by additional attacking ants significantly more than were juveniles. Our data suggest that the higher percentage of responsive adults within invaded populations is the result of within-lifetime selection acting against unresponsive adults, and/or lifetime exposure to fire ants triggering the retention of this juvenile behavior into adulthood, rather than selection acting on a heritable trait across generations.

A test of the coupling of predator defense morphology and behavior variation in two threespine stickleback populations

Abstract Among-population differences in morphology and behaviors such as boldness have been shown to co-vary with ecological conditions, including predation regime. However, between- and within-population covariation of predator defense morphology with variation in behaviors relevant to ecology and evolution (boldness, exploration, activity, sociability and aggressiveness, often defined as personality traits when they are consistent across time and contexts) have never been quantified together in a single study in juvenile fish from populations found in contrasting environments. We measured predator defense morphology differences between adults from two freshwater populations of threespine sticklebacks with different ecological conditions. We then quantified five behaviors in juveniles from both populations raised in a common environment. Wild-caught adults showed significant differences in predator defense morphology. One population had significantly lower lateral plate number, shorter dorsal spine, pelvic spine and pelvic girdle. Furthermore, 61% of individuals from that population showed an absence of pelvic spine and girdle. At the population level, we found that differences in defense morphology in adults between the two lakes were coupled with differences in behaviors in juveniles raised in a common environment. Levels of activity, aggressiveness and boldness were higher in juveniles from the population lacking predator defense structures. At the individual level, anti-predator morphology of adult females could not predict their offspring’s behavior, but juvenile coloration predicted individual boldness in a population-specific manner. Our results suggest that ecological conditions, as reflected in adult predator defense morphology, also affect juvenile behavior in threespine sticklebacks, resulting in trait co-specialization, and that there is a genetic or epigenetic component to these behavioral differences.

A Meta-analysis of Attachment to Parents and Delinquency

To investigate the link between attachment to parents and delinquency, and the potential moderating effects of age and sex, 74 published and unpublished manuscripts (N = 55,537 participants) were subjected to a multilevel meta-analysis. A mean small to moderate effect size was found (r = 0.18). Poor attachment to parents was significantly linked to delinquency in boys and girls. Stronger effect sizes were found for attachment to mothers than attachment to fathers. In addition, stronger effect sizes were found if the child and the parent had the same sex compared to cross-sex pairs of children and parents. Age of the participants moderated the link between attachment and delinquency: larger effect sizes were found in younger than in older participants. It can be concluded that attachment is associated with juvenile delinquency. Attachment could therefore be a target for intervention to reduce or prevent future delinquent behavior in juveniles.

Personality Matters: The Effect of Defiant Individualism on both Deviant Associations and Normative Behaviors among Juveniles in Rural North Carolina

The role of defiant individualism in the production of deviant behavior has not been extensively explored within Criminology. This study used data from a juvenile gang assessment of two rural counties in North Carolina to examine the effect of defiant individualism on association with deviant peers, association with gang members, school engagement and grade point average. The researchers developed a proprietary scale with which to measure defiant individualism. Additionally, an integrated defiance continuum was constructed in which to better contextualize the findings. Findings suggested that defiant individualism had positive relationships with both deviant peer associations and association with gang members. Furthermore, there were inverse relationships between defiant individualism and school engagement as well as grade point average. These statistics suggested that besides promoting deviant associations, defiant individualism also inhibited normative behaviors like school engagement and academic achievement which may actually ameliorate deviant behavior in juveniles.

Determinants of juvenile delinquent behaviour in the family

Children and adolescents are one of the most vulnerable social groups in the community. Copenhagen declaration has emphasized the fact that particular efforts should be devoted to children and adolescent protection with an aim for extension of social protection and decrease of easy vulnerability of humans. Children and adolescent behaviour is like a mirror which depicts the processes going on in the society, as well as the existing social and economic controversies. At present one can witness negative tendencies in children and adolescent behaviour in Latvia: they drop school early, lead a vagrant life, get used to drugs, violence grows, especially that of severe crimes. In the Resolution of the European Parliament of June 21, 2007 “On Juvenile Delinquency – Role of Women, Family and Community” it is also written, that children enter the world of crime much earlier. Certain emotional and behavioural peculiarities of children and adolescents can be taken as a norm at a definite age, however, there exist also such behavioural peculiarities, which essentially differ from the accepted norms. Causative factors of delinquent behaviour, as well as its consequences, are at a level of multiple systems. But, the first and the most significant in any person’s life is the family, and, consequently, it is important to learn and analyze what are the factors in the family which determine the formation of delinquent behaviour.

Behavior of juveniles of roach Rutilus rutilus (cyprinidae), produced by breeders from a tributary of the Rybinsk Reservoir and from a nonfreezing area of the Moskva River at variable temperatures

The study has revealed differences in search behavior among juvenile individuals of the roach Rutilus rutilus produced by breeders from a tributary of the Rybinsk Reservoir and from nonfreezing areas of the Moskva River. It has been shown that differences in behavioral responses of juveniles are minimal at a stable temperature (approximately 20°C). Gradually rising or falling temperatures lead to an increase in the variation of behavioral parameters. Response to rising temperature is more pronounced in juvenile roach individuals produced by breeders from the Rybinsk Reservoir tributary, while response to decreasing temperature is, on the contrary, more pronounced in individuals produced by breeders from the nonfreezing Moskva River area. Year-round occurrence in zones with heated water in the nonfreezing Moskva River area has probably contributed to a change in the roach population’s adaptation to cold, consolidated by selection at the genetic level over several generations.

Distribution patterns of the Chinese mitten crab (Eriocheir sinensis H. Milne Edwards, 1853) in Lake Vänern, Sweden

The catadromous Chinese mitten crab (CMC), Eriocheir sinensis is well known for its extensive invasion routes across the world. However, little is known about both adult and juvenile behaviour afte ...

A MODEL FOR GENOMIC IMPRINTING IN THE SOCIAL BRAIN: ELDERS

Genomic imprinting refers to the process whereby genes are silenced when inherited via sperm or egg. The most widely accepted theory for the evolution of genomic imprinting-the kinship theory-argues that conflict between maternally inherited and paternally inherited genes over phenotypes with asymmetric effects on matrilineal and patrilineal kin results in self-imposed silencing of one of the copies. This theory was originally developed in the context of fitness interactions within nuclear families, to understand intragenomic conflict in the embryo and infant, but it has recently been extended to encompass interactions within wider social groups, to understand intragenomic conflict over the social behavior of juveniles and adults. Here, we complete our model of genomic imprinting in the social brain by considering age-specific levels of expression in a society were generations overlap, to determine how intragenomic conflict plays out in older age. We determine the role of sex bias in juvenile dispersal, reproductive success, and adult mortality in mediating the direction and intensity of conflict over the competing demands of parental and communal care as the individual ages. We discover that sex-specific asymmetries in these demographic parameters result in intragenomic conflict at early age but this conflict gradually decays with age. Although individuals are riven by internal conflict in their youth and middle age, they put their demons to rest in later life.

Natal philopatry, ranging behavior, and habitat selection of juvenile bottlenose dolphins in Sarasota Bay, Florida

Movement patterns and habitat selection are influenced by factors such as resource availability, predation risk, and social interactions, and the relative importance of each of these variables can change over an animal’s life span. Although ranging patterns and habitat use of adult dolphins have been explored in some areas, relatively little is known about how these behaviors develop as young dolphins mature. This study explored natal philopatry during the juvenile period and behavioral development of ranging and habitat-use patterns in newly independent bottlenose dolphins (Tursiops truncatus) at a long-term study site in Sarasota Bay, Florida. To achieve this we used both long-term sighting data from the resident dolphin community in Sarasota Bay and new information on movements, habitat selection, and social associations collected through boat-based focalanimal behavioral observations on 27 individually identifiable juveniles during 2005–2008. We documented differences in ranging patterns and habitat use of juvenile dolphins by sex, season, and age, and investigated the degree of maternal influence on these behaviors and the functional significance of juvenile groups. We found that male and female dolphins in Sarasota Bay had similar ranging and habitat-selection patterns during the juvenile period. Both sexes exhibited a high degree of philopatry to natal areas as juveniles, with dispersal occurring only rarely by members of either sex. Seasonal and age-related differences in juvenile behavior were evident, and lasting maternal influences on habitat selection and ranging patterns postindependence are apparent. These findings provide some of the 1st information on juvenile marine mammal behavior that contributes to our understanding of resident inshore dolphin behavior throughout the life history and are potentially important to management and conservation efforts.