Plasticity and repeatability in spring migration and parturition dates with implications for annual reproductive success

Animals are faced with unprecedented challenges as environmental conditions change. Animals must display behavioral plasticity to acclimate to changing conditions, or phenotypic variation must exist within the population to allow for natural selection to change the distribution of trait values. The timing of migration and parturition relative to important annual environmental changes such as snowmelt and vegetation green-up and how they co-vary may influence reproductive success. We tested for plasticity and individual differences in migration and parturition timing as a function of the timing of snowmelt and green-up in a migratory herbivore (caribou; Rangifer tarandus, n = 92) using behavioral reaction norms. We tested whether timing of parturition, plasticity in parturition timing, or timing of green-up were correlated with calf survival. Migration and parturition timing were plastic to the timing of spring conditions, and we found moderate repeatability for migration timing, but no repeatability in timing of parturition. We detected a novel behavioral syndrome where timing of migration and timing of parturition were correlated. Our results suggest that observed shifts in caribou parturition timing in other populations are due to plasticity as opposed to an evolutionary response to changing conditions. We did not detect a correlation between annual reproductive success and either the timing of spring or plasticity to the timing of spring events. While this provides evidence that many populations may be buffered from the consequences of climate change via plasticity, we caution that a lack of repeatability in parturition timing could impede adaptation as climate warming increases.

Negative Symptoms and Behavioral Alterations Associated with Dorsolateral Prefrontal Syndrome in Patients with Schizophrenia

The present study had three main aims: (1) to explore the possible relationships between the two dimensions of negative symptoms (NS) with the three frontal behavioral syndromes (dorsolateral, orbitofrontal and the anterior or mesial cingulate circuit) in patients with schizophrenia; (2) to determine the influence of sociodemographic and clinical variables on the severity of the two dimensions of NS (expressive deficits and disordered relationships/avolition); and (3) to explore the possible relationships between the two dimensions of NS and social functioning. We evaluated a group of 33 patients with schizophrenia with a predominance of NS using the self-reported version of the Frontal System Behavior scale. To quantify the severity of NS, the Assessment of Negative Symptoms (SANS) scale was used. The results revealed that the two dimensions of NS correlate positively with the behavioral syndrome of dorsolateral prefrontal origin. Regarding the influence of sociodemographic and clinical variables, in patients with a long evolution the NS of the expressive deficits dimension were less severe than in patients with a short evolution. A negative correlation was found between the severity of NS of the disordered relationships/avolition dimension and perceived social functioning. Our results show the importance of differentiating between the two dimensions of NS to characterize better their possible frontal etiology and impact on clinical course and social functioning.

Lifetime stability of social traits in bottlenose dolphins

Behavioral phenotypic traits or “animal personalities” drive critical evolutionary processes such as fitness, disease and information spread. Yet the stability of behavioral traits, essential by definition, has rarely been measured over developmentally significant periods of time, limiting our understanding of how behavioral stability interacts with ontogeny. Based on 32 years of social behavioral data for 179 wild bottlenose dolphins, we show that social traits (associate number, time alone and in large groups) are stable from infancy to late adulthood. Multivariate analysis revealed strong relationships between these stable metrics within individuals, suggesting a complex behavioral syndrome comparable to human extraversion. Maternal effects (particularly vertical social learning) and sex-specific reproductive strategies are likely proximate and ultimate drivers for these patterns. We provide rare empirical evidence to demonstrate the persistence of social behavioral traits over decades in a non-human animal.

Daily activity rhythms, chronotypes, and risk-taking behavior in the signal crayfish

Consistent inter-individual differences in daily activity rhythms (i.e., chronotypes) can have ecological consequences in determining access to food resources and avoidance of predators. The most common measure to characterize chronotypes in animals as well as humans is the onset of activity (i.e., early or late chronotypes). However, daily activity rhythms may also differ in the relative amount of activity displayed at particular time periods. Moreover, chronotypes may also be linked to other consistent inter-individual differences in behavior (i.e., personality), such as the propensity to take risks. Here, we used the signal crayfish Pacifastacus leniusculus to test the presence of chronotypes and risk-taking personality traits and a potential behavioral syndrome between these traits. We first exposed crayfish to 5 days of light–darkness to measure daily activity rhythms and then we applied a visual predator-simulating stimulus in 2 different contexts (neutral and food). Our results showed consistent (i.e., across 5 days) inter-individual differences in the relative nocturnal activity displayed in the early and middle, but not in the late part of darkness hours. Moreover, while crayfish displayed inter-individual differences in risk-taking behavior, these were not found to be consistent across 2 contexts. Therefore, we were not able to formally test a behavioral syndrome between these 2 traits. In conclusion, our study provides the first evidence of chronotypes in the relative amount of activity displayed at particular time periods. This could be a valuable information for applied ecological aspects related to the signal crayfish, which is a major invasive species of freshwater ecosystems.

A behavioral syndrome linking boldness and flexibility facilitates invasion success in sticklebacks

ABSTRACTFor a species to expand its range, it needs to be good at dispersing and also capable of exploiting resources and adapting to different environments. Therefore, behavioral and cognitive traits could play key roles in facilitating invasion success. Here, we show that dispersing sticklebacks are bold, while sticklebacks that have recently established in a new region are flexible. Moreover, boldness and flexibility are negatively correlated with one another at the individual, family and population levels. Multiple lines of evidence suggest that the divergence in boldness and flexibility is likely to be evolutionary in origin. If boldness is favored in invaders during the initial dispersal stage, while flexibility is favored in recent immigrants during the establishment stage, then the link between boldness and flexibility could generate positive correlations between successes during both dispersal and establishment, and therefore play a key role in facilitating colonization success in sticklebacks and other organisms.

Environmental temperature during early life affects the personality of mosquitofish in adulthood

Personality has been observed in a variety of animal taxa with important implications in ecology and evolution. Exploring the influence of environmental temperature during early life on personality could help to understand the ontogeny of this phenotypic trait in animals. In this study, we reared newborn mosquitofish Gambusia affinis at high (30°C) and low (25°C) water temperatures and measured their shyness and exploration upon sexual maturity. We tested the repeatability of each behavioral trait; the correlation between them; and the effects of rearing temperature, sex, and body length on the behaviors. When growing up at low temperatures, female fish exhibited repeatability in shyness and exploration, and males exhibited marginal repeatability in shyness. However, neither of the 2 behaviors were repeatable when the fish were reared at high temperatures. There was a negative correlation between shyness and exploration, indicating that the 2 behaviors comprise a behavioral syndrome in this species. Mosquitofish reared at high temperatures were more explorative than those reared at low temperatures, while there was no difference in shyness between the 2 treatments. Body length and sex had no significant effects on the average values of the 2 behaviors. The results indicate that environmental temperature during early life could shape the personality of mosquitofish and modify the average of the behavioral traits. These findings might provide insights to understand the ontogeny of animal personality and how changes in environmental temperature influence animal dispersal by shaping their personality.

Consistent Behavioral Syndrome Across Seasons in an Invasive Freshwater Fish

Understanding the linkage between behavioral types and dispersal tendency has become a pressing issue in light of global change and biological invasions. Here, we explore whether dispersing individuals exhibit behavioral types that differ from those remaining in the source population. We investigated a feral population of guppies (Poecilia reticulata) that undergoes a yearly range shift cycle. Guppies are among the most widespread invasive species in the world, but in temperate regions these tropical fish can only survive in winter-warm freshwaters. Established in a thermally-altered stream in Germany, guppies are confined to a warm-water influx in winter, but can spread to peripheral parts as these become thermally accessible. We sampled fish from the source population and a winter-abandoned site in March, June and August. Fish were tested for boldness, sociability and activity involving open-field tests including interactions with a robotic social partner. Guppies differed consistently among each other in all three traits within each sample. Average trait expression in the source population differed across seasons, however, we could not detect differences between source and downstream population. Instead, all populations exhibited a remarkably stable behavioral syndrome between boldness and activity despite strong seasonal changes in water temperature and associated environmental factors. We conclude that random drift (opposed to personality-biased dispersal) is a more likely dispersal mode for guppies, at least in the investigated stream. In the face of fluctuating environments, guppies seem to be extremely effective in keeping behavioral expressions constant, which could help explain their successful invasion and adaptation to new and disturbed habitats.

The Developmental Plasticity of Boldness and Aggressiveness in Juvenile and Adult Swimming Crab (Portunus trituberculatus)

Boldness and aggressiveness are crucial behavioral traits in the field of animal personality, and both have important ecological and evolutionary significance. As swimming crabs (Portunus trituberculatus) are aggressive, their production is affected; thus, it is important to study their behavior. To assess the relationship between boldness and aggressiveness of male P. trituberculatus and the differences between their different life stages, we determined the individual differences in these two traits in juvenile and adult crabs under laboratory conditions. Based on the k-means cluster analysis, boldness of crabs is classified according to their rush to adventure, and aggressiveness of crabs is classified according to their aggressive behavior toward conspecifics. The results show that the personality classification of juvenile and adult crabs was consistent. Boldness was divided into three levels: bold, middle, and shy. Aggressiveness was divided into two levels: aggressiveness and non-aggressiveness. The personality of juveniles and adults P. trituberculatus males was significantly different; juveniles presented higher aggressiveness and lower boldness than adults. Additionally, a significant positive correlation between boldness and aggressiveness of adult crabs was verified (P = 0.001, ρ = 0.271). However, this correlation in juvenile crabs was not significant (P = 0.702, ρ = 0.042). These preliminary results indicate that the personality of P. trituberculatus males has developmental plasticity and adults have the boldness-aggressiveness behavioral syndrome.