Senegalese sole (Solea senegalensis) coping styles are consistent over time: behavioural and physiological responses during ontogenesis

Fish personality: meta-theoretical issues, personality dimensions, and applications to neuroscience and psychopathology

While the field of personality neuroscience has extensively focused on humans and, in a few cases, primates and rodents, a wide range of research on fish personality has emerged in the last decades. This research is focused mainly on the ecological and evolutionary causes of individual differences and also aimed less extensively at proximal mechanisms (e.g., neurochemistry or genetics). We argue that, if consistent and intentional work is made to solve some of the meta-theoretical issues of personality research both on fish and mammals, fish personality research can lead to important advances in personality neuroscience as a whole. The five dimensions of personality in fish (shyness-boldness, exploration-avoidance, activity, aggressiveness, and sociability) need to be translated into models that explicitly recognize the impacts of personality in psychopathology, synergizing research on fish as model organisms in experimental psychopathology, personality neuroscience, and ecological-ethological approaches to the evolutionary underpinnings of personality to produce a powerful framework to understand individual differences.

The ontogeny of personality: Repeatability of social and escape behaviors across developmental stages in Siberian hamsters (Phodopus sungorus)

Animal personality is defined as behavioral tendencies that are consistent across time and contexts within an individual, but differ across individuals. Studies investigating personality typically examine individuals across short time periods or within a single life stage. Growing evidence suggests that personality may be less stable across life stages, highlighting the need to consider the effects of ontogeny on the expression of consistent behavioral traits. We investigated individual consistency in social and escape behaviors across developmental stages using Siberian hamsters (Phodopus sungorus). To determine whether individuals were consistent in these behaviors as juveniles and across developmental stages, we measured male and female social and escape behaviors twice as juveniles and once as adults. Individuals' social scores were significantly repeatable within the juvenile stage, but not across developmental stages. In contrast, escape scores were highly repeatable across developmental stages, with males' scores being more repeatable than females' scores. Our results support previous findings that personality traits, especially those associated with social behavior, are less stable across development, whereas behaviors associated with stress or coping may represent a more permanent feature of an individual's phenotype. Our results also indicate potential sex differences in long-term repeatability of personality. Considering how ontogeny affects animal personality for males and females can provide insight into the evolution and mechanisms that maintain animal personality.

Gaps to Address in Ecological Studies of Temperament and Physiology

Ecology is a diverse field with many researchers interested in drivers and consequences of variability within populations. Two aspects of variability that have been addressed are behavioral and physiological. While these have been shown to separately influence ecological outcomes such as survival, reproductive success and fitness, combined they could better predict within-population variability in survival and fitness. Recently there has been a focus on potential fitness outcomes of consistent behavioral traits that are referred to as personality or temperament (e.g. boldness, sociability, exploration, etc.). Given this recent focus, it is an optimal time to identify areas to supplement in this field, particularly in determining the relationship between temperament and physiological traits. To maximize progress, in this perspective paper we propose that the following two areas be addressed: (1) increased diversity of species, and (2) increased number of physiological processes studied, with an eye toward using more representative and relatively consistent measures across studies. We first highlight information that has been gleaned from species that are frequently studied to determine how animal personality relates to physiology and/or survival/fitness. We then shine a spotlight on important taxa that have been understudied and that can contribute meaningful, complementary information to this area of research. And last, we propose a brief array of physiological processes to relate to temperament, and that can significantly impact fitness, and that may be accessible in field studies.

Exploring the relationship between stress coping styles and sex, origin and reproductive success, in Senegalese sole (Solea senegalensis) breeders in captivity

Individual animals commonly adopt different stress coping styles that have been shown to impact reproductive success and differ between sexes (female/male) and origin (wild/hatchery). Hatchery reared Senegalese sole (Solea senegalensis) exhibit a behavioural reproductive dysfunction and a complete failure to spawn viable eggs. Hence, the present study examined whether 1) reproductive success of Senegalese sole was linked to coping styles and 2) behavioural differences exist in relation to sex or origin. A total of 198 breeders held in two research institutions were submitted to three individual tests (restraining, new environment and confinement) and one grouping test (risk taking). In addition, a blood sample to quantify cortisol, glucose and lactate levels was obtained from each individual after completing the individual tests. Senegalese sole breeders showed individual differences in behaviour across the different behavioural tests that were consistent with proactive and reactive coping styles traits. However, the most striking result was that reproductive success, sex and origin of Senegalese sole was not biased to any specific coping style. Indeed, the behavioural responses were similar and consistent between fish grouped by reproductive success, sex and origin. This study presented information that contrasts with different studies on dominant aggressive species and indicated that social non-aggressive species such as Senegalese sole follow a cooperative strategy that favours equal opportunities between stress coping styles and sexes. Therefore, results suggest that maintaining both coping styles strategies are fundamental for a sustainable breeder population approach.