RESUMEN

An individual's behavioral tendencies (i.e., personality or temperament) can influence its interactions with the environment and thus have important ecological and evolutionary consequences for animal populations. Boldness, defined as an individual's tendency to engage in risk-taking activities, is a phenotypically variable trait linked with numerous behavioral and fitness outcomes in free-ranging animals. We examined variation and repeatability of boldness and other behavioral characteristics in two wild Eastern Box Turtle (Terrapene carolina carolina) populations using radiotelemetry, and assessed fitness correlates of boldness over multiple years. We observed large amounts of among-individual variation and within-individual consistency (i.e., repeatability) of boldness as measured by their head emergence latency following a standardized confinement assay. Individuals were also consistent in several in-field behaviors including movement rate, home range size, and date of emergence from overwintering refuges. Individuals with shorter head emergence latencies (i.e., bolder turtles) had larger home ranges, emerged earlier from overwintering dormancy, and experienced moderately lower survival compared with shy individuals. Boldness did not affect time spent within the thermal preference range, somatic growth rates, or the frequency of mating or same-sex aggressive encounters. Boldness and its effects on in-field behaviors differed between sexes and populations, and the relationship between boldness and survival was temporally variable. Our results suggest possible intrinsic behavioral types in T. c. carolina and highlight the importance of long-term and multipopulation studies when examining ecological and evolutionary processes that shape personality phenotypes in turtles.

RESUMEN

Recent research has found that individuals often vary in how consistently they express their behavior over time (i.e., behavioral predictability) and suggested that these individual differences may be heritable. However, little is known about the intrinsic factors that drive variation in the predictability of behavior. Indeed, whether variation in behavioral predictability is sex-specific is not clear. This is important, as behavioral predictability has been associated with vulnerability to predation, suggesting that the predictability of behavioral traits may have key fitness implications. We investigated whether male and female eastern mosquitofish (Gambusia holbrooki) differed in the predictability of their risk-taking behavior. Specifically, over a total of 954 behavioral trials, we repeatedly measured risk-taking behavior with three commonly used assays-refuge-use, thigmotaxis, and foraging latency. We predicted that there would be consistent sex differences in both mean-level risk-taking behavior and behavioral predictability across the assays. We found that risk-taking behavior was repeatable within each assay, and that some individuals were consistently bolder than others across all three assays. There were also consistent sex differences in mean-level risk-taking behavior, with males being bolder across all three assays compared to females. In contrast, both the magnitude and direction of sex differences in behavioral predictability were assay-specific. Taken together, these results highlight that behavioral predictability may be independent from underlying mean-level behavioral traits and suggest that males and females may differentially adjust the consistency of their risk-taking behavior in response to subtle changes in environmental conditions.

RESUMEN

AbstractConsiderable theoretical work predicts that intraspecific trait variation can have profound ecological consequences by altering species interactions. Because of their high flexibility, behavioral traits may be especially relevant in mediating how species respond to one another, thus affecting food web dynamics and ecosystem functioning. However, empirical evidence supporting this idea is limited. Here, we generated predator groups where we manipulated the composition of behavioral types within the groups to assess effects on predator growth rates, prey communities, basal resources, and ecosystem functioning in replicated outdoor ponds. Using European perch (Perca fluviatilis), we created three types of predator populations: two where all individuals expressed either bold or shy phenotypes and one that contained a mix of individuals of the two behavioral types. Bold perch grew faster in mixed populations, indicating that predator growth depends on each individual's behavioral type and that of its group members. However, there was no evidence that the behavioral composition of the perch population directly altered the dynamics of lower trophic levels. Instead, final perch biomass, not behavioral composition, had the strongest influence on lower trophic levels. Thus, the central question may not be whether predator behavior matters at all for trophic dynamics but rather when behavioral effects will predominate over effects of other influences, such as predator biomass variation.

Asunto(s)

RESUMEN

Individuals of a population may vary along a pace-of-life syndrome from highly fecund, short-lived, bold, dispersive "fast" types at one end of the spectrum to less fecund, long-lived, shy, plastic "slow" types at the other end. Risk-taking behavior might mediate the underlying life history trade-off, but empirical evidence supporting this hypothesis is still ambiguous. Using experimentally created populations of common voles (Microtus arvalis)-a species with distinct seasonal life history trajectories-we aimed to test whether individual differences in boldness behavior covary with risk taking, space use, and fitness. We quantified risk taking, space use (via automated tracking), survival, and reproductive success (via genetic parentage analysis) in 8 to 14 experimental, mixed-sex populations of 113 common voles of known boldness type in large grassland enclosures over a significant part of their adult life span and two reproductive events. Populations were assorted to contain extreme boldness types (bold or shy) of both sexes. Bolder individuals took more risks than shyer ones, which did not affect survival. Bolder males but not females produced more offspring than shy conspecifics. Daily home range and core area sizes, based on 95% and 50% Kernel density estimates (20 ± 10 per individual, n = 54 individuals), were highly repeatable over time. Individual space use unfolded differently for sex-boldness type combinations over the course of the experiment. While day ranges decreased for shy females, they increased for bold females and all males. Space use trajectories may, hence, indicate differences in coping styles when confronted with a novel social and physical environment. Thus, interindividual differences in boldness predict risk taking under near-natural conditions and have consequences for fitness in males, which have a higher reproductive potential than females. Given extreme inter- and intra-annual fluctuations in population density in the study species and its short life span, density-dependent fluctuating selection operating differently on the sexes might maintain (co)variation in boldness, risk taking, and pace-of-life.

RESUMEN

Spiders are useful models for testing different hypotheses and methodologies relating to animal personality and behavioral syndromes because they show a range of behavioral types and unique physiological traits (e.g., silk and venom) that are not observed in many other animals. These characteristics allow for a unique understanding of how physiology, behavioral plasticity, and personality interact across different contexts to affect spider's individual fitness and survival. However, the relative effect of extrinsic factors on physiological traits (silk, venom, and neurohormones) that play an important role in spider survival, and which may impact personality, has received less attention. The goal of this review is to explore how the environment, experience, ontogeny, and physiology interact to affect spider personality types across different contexts. We highlight physiological traits, such as neurohormones, and unique spider biochemical weapons, namely silks and venoms, to explore how the use of these traits might, or might not, be constrained or limited by particular behavioral types. We argue that, to develop a comprehensive understanding of the flexibility and persistence of specific behavioral types in spiders, it is necessary to incorporate these underlying mechanisms into a synthesized whole, alongside other extrinsic and intrinsic factors.

RESUMEN

Disease onset and type A behavioral pattern (TABP) are important characteristics of the clinical manifestations of chronic diseases. The aim of this work is to study the prevalence and role of TABP in patients with rheumatoid arthritis (RA) with the onset of the disease at different periods of ontogenesis. 82 patients were examined, which were divided into groups depending on the age of RA onset. The first group included patients with RA onset at reproductive age (from 18 to 44 years). The second group included patients with the onset of RA in the middle age (from 45 to 59 years). The third group consisted of patients with the onset of RA in old age (from 60 to 74 years). The fourth group consisted of patients with the onset of RA in old age (75 years and older). Diagnosis of TABP was carried out using a special questionnaire. The group with a debut in the reproductive period had the largest number of patients with RA of the 1st and 2nd line of relationship, as well as the highest incidence of TABP, which was associated with a greater expression of such personal qualities as ambition and hostility. This group had the highest number of ankylosis, as well as the highest frequency of systemic lesions. The second group demonstrated classic rheumatoid patterns. The third group with debut in old age had the most favorable clinical picture, incl. the lowest immunological activity in terms of the сirculating immune complexes (CICs) level, associated with the lowest severity of articular syndrome, with the lowest number of erosions and the frequency of systemic manifestations. The fourth group with a debut in old age demonstrated the highest inflammatory activity and specific immunological activity in terms of rheumatoid factor and CICs levels, as well as the highest clinical severity of the articular syndrome. Thus, the ontogenetic debut of RA determines its clinical and laboratory features and is associated with the presence and characteristics of TABP.

Asunto(s)

RESUMEN

Intraspecific differences in the dispersal propensity of animals have been linked to interindividual variation in inherent tendencies (i.e., personality or behavioral type) that influence multiple aspects of an individual's behavior. Studies linking dispersal propensity and personality often (1) focus on defining behavioral tendencies with a single behavioral trait rather than multiple, (2) do not recognize that invertebrates may have behavioral tendencies that influence dispersal, and (3) do not consider how the behavioral type of other individuals affects the dispersal propensity of an individual. We documented multiple foraging behaviors of an aquatic predatory insect (Notonecta irrorata) and found that Notonecta individuals differ in their inherent behavioral tendency (i.e., degree of boldness); all foraging behaviors were correlated such that riskier behaviors were exhibited by the same individuals. We conducted an experiment in which we varied which behavioral types of Notonecta were placed in outdoor pools (passive, bold or both types present) and quantified how long it took for individuals to disperse. Passive and bold individuals had a similar propensity to disperse but the dispersal propensity of each behavioral type was influenced by the behavioral type of other conspecifics present in the pool. Our work reveals that (1) invertebrates have inherent behavioral tendencies that vary among individuals but these tendencies do not necessarily impact all of the behavior displayed by the individual (i.e., impact foraging but not dispersal) and (2) the inherent behavioral tendency of other individuals with which an animal co-occurs can affect habitat patch dynamics such as predation, competition, or colonization.

Asunto(s)

RESUMEN

Animal tracking and biologging devices record large amounts of data on individual movement behaviors in natural environments. In these data, movement ecologists often view unexplained variation around the mean as "noise" when studying patterns at the population level. In the field of behavioral ecology, however, focus has shifted from population means to the biological underpinnings of variation around means. Specifically, behavioral ecologists use repeated measures of individual behavior to partition behavioral variability into intrinsic among-individual variation and reversible behavioral plasticity and to quantify: a) individual variation in behavioral types (i.e. different average behavioral expression), b) individual variation in behavioral plasticity (i.e. different responsiveness of individuals to environmental gradients), c) individual variation in behavioral predictability (i.e. different residual within-individual variability of behavior around the mean), and d) correlations among these components and correlations in suites of behaviors, called 'behavioral syndromes'. We here suggest that partitioning behavioral variability in animal movements will further the integration of movement ecology with other fields of behavioral ecology. We provide a literature review illustrating that individual differences in movement behaviors are insightful for wildlife and conservation studies and give recommendations regarding the data required for addressing such questions. In the accompanying R tutorial we provide a guide to the statistical approaches quantifying the different aspects of among-individual variation. We use movement data from 35 African elephants and show that elephants differ in a) their average behavior for three common movement behaviors, b) the rate at which they adjusted movement over a temporal gradient, and c) their behavioral predictability (ranging from more to less predictable individuals). Finally, two of the three movement behaviors were correlated into a behavioral syndrome (d), with farther moving individuals having shorter mean residence times. Though not explicitly tested here, individual differences in movement and predictability can affect an individual's risk to be hunted or poached and could therefore open new avenues for conservation biologists to assess population viability. We hope that this review, tutorial, and worked example will encourage movement ecologists to examine the biology of individual variation in animal movements hidden behind the population mean.

RESUMEN

Consistent individual differences in behavior [i.e., behavioral types (BTs)], are common across the animal kingdom. Consistency can make behavior an adaptive trait for mate choice decisions. Here, we present a conceptual framework to explain how and why females might evaluate a male's BT before mating. Because BTs are consistent across time or context, a male's BT can be a reliable indicator of his potential to provide direct benefits. Heritable BTs can enable informed mate choice via indirect benefits. Many key issues regarding patterns of mate choice, including sensory biases, context dependence, and assortative mating apply to BT-dependent mate choice. Understanding the relationship between BTs and mate choice may offer insights into patterns of variation and consistency common in behavioral traits.

Asunto(s)

RESUMEN

Temporally consistent individual differences in behavior impact many ecological processes. We simultaneously examined the effects of individual variation in prey activity level, covering behavior, and body size on prey survival with predators using an urchin-lobster system. Specifically, we tested the hypothesis that slow-moving purple sea urchins (Strongylocentrotus purpuratus) and urchins who deploy extensive substrate (pebbles and stones) covering behavior will out-survive active urchins that deploy little to no covering behavior when pitted against a predator, the California spiny lobster (Panulirus interruptus). We evaluated this hypothesis by first confirming whether individual urchins exhibit temporally consistent differences in activity level and covering behavior, which they did. Next, we placed groups of four urchins in mesocosms with single lobster and monitored urchin survival for 108 hours. High activity level was negatively associated with survival, whereas urchin size and covering behavior independently did not influence survival. The negative effect of urchin activity level on urchin survival was strong for smaller urchins and weaker for large urchins. Taken together, these results suggest that purple urchin activity level and size jointly determine their susceptibility to predation by lobsters. This is potentially of great interest, because predation by recovering lobster populations could alter the stability of kelp forests by culling specific phenotypes, like foraging phenotypes, from urchin populations.

RESUMEN

In monogamous species, partner compatibility is a key factor influencing pairing and reproductive success. In pairs with biparental care, studies have mostly focused on behavioral compatibility because it is likely to encourage the coordination of parental care within pairs, leading to a better reproductive success. Behavior modulation, throughout the breeding season and as a function of the social context, is under the regulatory feedback control of endocrine mechanisms. From this link, the idea of hormonal partner compatibility as a key component of pair cohesion and maintenance has recently emerged. Here, we investigated the link between partner behavioral assortment and their hormonal response to the pairing context. We formed assortative and disassortative pairs of convict cichlids based on their behavioral type (proactive or reactive) and took hormone and fitness measurements. Testosterone, 11-ketotestosterone, 17ß-estradiol and cortisol levels were measured from fish-holding water before and after pair formation. We found no relationship between the behavioral type of individuals and their pre-pairing hormone levels. Only the level of cortisol was affected by the partner but independently of its behavioral type. Reproductive success was not affected by the level of hormonal similarity within pairs, but we found that the variation in 11-ketotestosterone similarity between the isolated context and the pairing context was related to spawning size, and the variation in cortisol similarity to the number of fry. Behavioral compatibility does not reflect hormonal compatibility in the convict cichlid, but the relationship between reproductive success and the flexibility of hormonal similarity between partners suggests hormonal adjustment within pairs in this species.

Asunto(s)

RESUMEN

Temporally consistent individual differences in behavior, also known as animal personality, can have large impacts on individual fitness. Here, we explore the degree to which individual differences in anti-predator response (or boldness) influence survival rates in groups of snails Chlorostoma funebralis when they encounter a predatory sea star Pisaster giganteus. The snail C. funebralis shows consistent individual variation in predator response where some fearful snails actively flee bodies of water occupied by predators whereas bolder snails consistently do not. We show here that bold snails are significantly more likely to survive encounters with a predatory sea star and, somewhat counterintuitively, fearful snails actually suffer higher mortality rates. We also found that smaller snails and those occurring at higher experimental densities experienced higher per capita survival rates. Positive effects of prey boldness on survival are not uncommonly reported in the animal personality literature; however, such results are inconsistent with classic animal personality theory borrowed from the optimal foraging literature. The findings herein add to the growing body of evidence that consistent individual differences in behavior can impact predator-prey interactions and that boldness is potentially under positive predator-driven selection in some systems.

RESUMEN

Behavioral traits and diet were traditionally thought to be highly plastic within individuals. This view was espoused in the widespread use of optimality models, which broadly predict that individuals can modify behavioral traits and diet across ecological contexts to maximize fitness. Yet, research conducted over the past 15 years supports an alternative view; fundamental behavioral traits (e.g., activity level, exploration, sociability, boldness and aggressiveness) and diet often vary among individuals and this variation persists over time and across contexts. This phenomenon has been termed animal personality with regard to behavioral traits and individual specialization with regard to diet. While these aspects of individual-level phenotypic variation have been thus far studied in isolation, emerging evidence suggests that personality and individual specialization may covary, or even be causally related. Building on this work, we present the overarching hypothesis that animal personality can drive specialization through individual differences in various aspects of consumer foraging behavior. Specifically, we suggest pathways by which consumer personality traits influence foraging activity, risk-dependent foraging, roles in social foraging groups, spatial aspects of foraging and physiological drivers of foraging, which in turn can lead to consistent individual differences in food resource use. These pathways provide a basis for generating testable hypotheses directly linking animal personality to ecological dynamics, a major goal in contemporary behavioral ecology.

Asunto(s)

RESUMEN

There can be substantial variation among individuals within a species in how they behave, even under similar conditions; this pattern is found in many species and across taxa. However, the mechanisms that give rise to this behavioral variation are often unclear. This study investigated the influence of environmental manipulations during development on behavioral variation in hatchlings of the red-eared slider turtle (Trachemys scripta). First, we examined the effects of three manipulations during incubation (estrone sulfate exposure, corticosterone exposure, and thermal fluctuations) on hatchling righting response and exploration. Second, we determined whether hatchlings showed consistent differences (i.e. behavioral types) in their righting response and exploration across days and months, and whether these behaviors were correlated with one another. Finally, we examined whether righting response was predictive of ecologically relevant behaviors such as habitat choice and dispersal. Hatchling behavior was robust to our early manipulations; none of the pre-hatch treatments affected later behavior. There were significant clutch effects, which due to the split-clutch design suggests genetic underpinnings and/or maternal effects. We found evidence for behavioral types in turtles; both righting response and exploration were strongly repeatable and these behaviors were positively correlated. Righting response was not predictive of dispersal ability in the field, necessitating a revision in the general interpretations of righting response as a proxy for dispersal ability in turtles. Thus, turtle hatchlings show consistent behavioral differences that are robust to early developmental manipulations, and while not necessarily predictive of dispersal, these behavioral types can have important consequences throughout ontogeny.

Asunto(s)