State and physiology behind personality in arthropods: a review

Abstract

In the endeavour to understand the causes and consequences of the variation in animal personality, a wide range of studies were carried out, utilising various aspects to make sense of this biological phenomenon. One such aspect integrated the study of physiological traits, investigating hypothesised physiological correlates of personality. Although many of such studies were carried out on vertebrates (predominantly on birds and mammals), studies using arthropods (mainly insects) as model organisms were also at the forefront of this area of research. In order to review the current state of knowledge on the relationship between personality and the most frequently studied physiological parameters in arthropods, we searched for scientific articles that investigated this relationship. In our review, we only included papers utilising a repeated-measures methodology to be conceptually and formally concordant with the study of animal personality. Based on our literature survey, metabolic rate, thermal physiology, immunophysiology, and endocrine regulation, as well as exogenous agents (such as toxins) were often identified as significant affectors shaping animal personality in arthropods. We found only weak support for state-dependence of personality when the state is approximated by singular elements (or effectors) of condition. We conclude that a more comprehensive integration of physiological parameters with condition may be required for a better understanding of state’s importance in animal personality. Also, a notable knowledge gap persists in arthropods regarding the association between metabolic rate and hormonal regulation, and their combined effects on personality. We discuss the findings published on the physiological correlates of animal personality in arthropods with the aim to summarise current knowledge, putting it into the context of current theory on the origin of animal personality.

State-dependency of behavioural traits is a function of the life-stage in a holometabolous insect

“…Effect of state variables, such as body condition, on behavioural traits of an individual has been widely documented (Scharf, 2016; Rádai et al ., 2022), but empirical evidence for how such effects may vary with life-stage is sparse. In our study we used starvation to manipulate the body condition of larvae and adults in A. rosae .…”

“…Similar to our results, a recent meta-analysis revealed that the effect of poor nutrition on risk-taking behaviour could be life-stage dependent, with juveniles showing stronger responses and higher risk-taking behaviour in low-nutrition conditions while the effect on adults was less unequivocal (Moran et al ., 2021). Life stage-specific effects on behaviour have been documented in previous studies (Polverino et al ., 2016; Rádai et al ., 2022), although few studies have documented such effects in holometabolous insects which occupy distinct niches in the juvenile and adult stage. The need to adjust to conditions of lower food availability may lead to individualised niche conformance (as defined in Müller et al ., 2020).…”

“…This variation between individuals in state can then translate into between-individual differences in behavioural traits (Niemelä & Dingemanse, 2018; Edmunds et al ., 2021). Moreover, the life-stage at which an individual experiences a state could be an important determining factor for the expressed behaviour (Sherratt & Morand-Ferron, 2018; Moran et al ., 2021; Rádai et al ., 2022). Even for the same state, different behavioural strategies may be adaptive depending on the life-stage at which the state is experienced by an individual.…”

Context-dependent effects of thermal acclimation on physiological correlates of animal personality in Asiatic toads

“…Moreover, whether positive or negative feedback predominates within populations depends on the selective landscape [5]. This context-dependent selection on individual state may explain the observed weak associations between intrinsic states (such as metabolic rate (MR), plasma hormone levels or body mass) and personality in recent meta-analytic reviews [6][7][8]. For example, Belgrad et al [9] demonstrated that boldness in mud crabs was positively correlated with short-term energy storage during the early spawning season, but negatively correlated with long-term energy storage during the later spawning season.…”

“…As a result, GCs may serve as an important mediator of the feedback between MR and personality [30,31]. However, the causal relationships between MR, GCs and personality remain unclear [7,32]. One possibility is that GCs affect energy metabolism, which in turn affects personality, resulting in the MR-personality association [10,32].…”