Temporal repeatability of behaviour in a lizard: implications for behavioural syndrome studies

It is well established that, across taxa, individuals within populations exhibit consistent differences in their behaviour across time and/or contexts. Further, the functional coupling of traits may result in the formation of a behavioural syndrome. Despite extensive evidence on the existence of consistent among-individual differences in behaviour and behavioural syndromes in the animal realm, these findings are predominately based upon short-term assessments, leading to questions regarding their stability over longer periods. Understanding if these estimates are temporally stable would allow predictions of individual behaviour to be made using short-term repeated measures. Here, we used 57 adult male delicate skinks (Lampropholis delicata) to evaluate the stability of behavioural variation observed both among (animal personality and behavioural plasticity) and within individuals (behavioural predictability), as well as behavioural syndromes, across short (four weeks) and long (five months) timeframes. To do so, we repeatedly assayed activity, exploration, and boldness five times per each individual. Overall, our study revealed complex patterns of behavioural variation and trait (co)variation over time. Activity was always repeatable across time intervals, whereas behavioural differences among individuals in exploration and boldness were not consistent. Yet a behavioural syndrome between activity and exploration was detected at both shorter and longer temporal scales, suggesting that syndrome structure in these traits does not vary as a function of time. Our findings indicate that, at least for some traits (e.g. activity) and studies, short-term measures may be adequate in serving as a proxy for long-term variation in individual behaviour, and to reveal the existence of behavioural syndromes at the population level

Biological invasions as a selective filter driving behavioral divergence

Biological invasions are a multi-stage process (i.e., transport, introduction, establishment, spread), with each stage potentially acting as a selective filter on traits associated with invasion success. Behavior (e.g., exploration, activity, boldness) plays a key role in facilitating species introductions, but whether invasion acts as a selective filter on such traits is not well known. Here we capitalize on the well-characterized introduction of an invasive lizard (Lampropholis delicata) across three independent lineages throughout the Pacific, and show that invasion shifted behavioral trait means and reduced among-individual variation-two key predictions of the selective filter hypothesis. Moreover, lizards from all three invasive ranges were also more behaviorally plastic (i.e., greater within-individual variation) than their native range counterparts. We provide support for the importance of selective filtering of behavioral traits in a widespread invasion. Given that invasive species are a leading driver of global biodiversity loss, understanding how invasion selects for specific behaviors is critical for improving predictions of the effects of alien species on invaded communities.Invasive species are a leading driver of global biodiversity loss. Here, the authors show that the process of invasion itself can promote behavioral changes important to the success of widespread invaders, with implications for understanding the effects of alien species on invaded communities

Data from: Thermal effects on survival and reproductive performance vary according to personality type

Understanding the ecological and evolutionary consequences of individual behavioral variation has become a major focus in behavioral ecology, yet we still know remarkably little about how abiotic and biotic factors influence personality-dependent fitness trade-offs in naturally occurring systems. In particular, fitness trade-offs associated with abiotic factors remain underrepresented in the animal personality literature. Here, we examine the interacting effects of personality and temperature on survival and reproduction—both at the individual and colony level—using the socially polymorphic spider Anelosimus studiosus as a model system. Overall, temperature had a profound effect on survival and reproduction, but the effect differed according to both individual personality and the personality composition of colonies. Temperature was positively correlated with mortality rates but negatively correlated with reproductive rates in aggressive individuals, whereas the opposite was true in docile individuals. Colonies composed of either all aggressive or all docile individuals suffered reduced reproductive rates in high and low temperatures, respectively. In contrast, colonies composed of a mixture of aggressive and docile individuals performed equally well at both high and low temperatures, suggesting that some aspect of colony living helps buffer individuals with ill-suited personalities from environmental conditions that would otherwise lead to their demise. Our study demonstrates the need to consider both abiotic and biotic (i.e., social) context when assessing the impact of personality on fitness

Data from: Integrating thermal physiology within a syndrome: locomotion, personality and habitat selection in an ectotherm

1. Physiology and temperature can both have a profound influence on behaviour and metabolism. Despite this, thermal physiology has rarely been considered within the animal personality framework, but could be an inherent mechanism maintaining consistent individual differences in behaviour, particularly in species that need to thermoregulate (i.e. ectotherms). 2. Here, we present evidence for a thermal-behavioural syndrome and detail how it is linked to variation in habitat selection in an Australian lizard, the delicate skink, Lampropholis delicata. 3. We predicted that individuals would occur along a cold-hot continuum – analogues to the slow-fast continuum proposed by the pace-of-life hypothesis - whereby an individual’s placement along a thermal physiological axis will correspond with their placement along a personality axis. We first tested the thermal-behavioural syndrome by measuring the thermal preferences and optimal performance temperature of individual skinks and linking it to their activity, exploratory, social and boldness behaviours. 4. In line with our predictions, we found that individuals with a ‘hot’ thermal type performed optimally at higher temperatures, had faster sprint speeds and were more active, explorative and bold relative to ‘cold’ thermal types. 5. We then monitored each individual’s habitat selection within an artificial environment containing three microhabitats differing in their thermal characteristics. 6. We found that an individual’s thermal type mediated their use of habitat, in which ‘hot’ individuals utilised a hotter microhabitat more regularly than both ‘cold’ and ‘intermediate’ thermal types, suggesting that the thermal-behavioural syndrome could drive ecological niche partitioning in this species. 7. We envisage that the thermal-behavioural syndrome concept is likely to extend to other study systems, particularly to ectothermic organisms that rely heavily on behavioural thermoregulation to maintain optimal body temperature

Data from: Thermal physiology: a new dimension of the pace-of-life syndrome

1) Current syndrome research focuses primarily on behavior with few incorporating components of physiology. One such syndrome is the Pace-of-Life Syndrome (POLS) which describes covariation between behaviour, metabolism immunity, hormonal response, and life history traits. Despite the strong effect temperature has on behavior, thermal physiology has yet to be considered within this syndrome framework. 2) We proposed the POLS to be extended to include a new dimension, the cold-hot axis. Under this premise, it is predicted that thermal physiology and behavior would covary whereby individual positioning along the thermal continuum would coincide with that of the behavioral continuum. 3) This hypothesis was tested by measuring thermal traits of delicate skinks (Lampropholis delicata) and linking it to their behavior. Principal components analysis and structural equation modelling were used to determine if traits were structured within the Pace-of-Life Syndrome (POLS) and to characterize the direction of their interactions. 4) Model results supported the inclusion of the cold-hot axis into the POLS and indicated that thermal physiology was the driver of this relationship, in that thermal traits either constrained or promoted activity, exploration, boldness, and social behavior. 5) This study highlights the need to integrate thermal physiology within a syndrome framework

Individual_performance_DRYAD

Results from an experimental lab study assessing the impact of temperature on fitness in spiders with different personalities. Data include day of death (in cases where individuals died before the end of a 40 day period) and number of egg cases produced by survivors

Colony_performance_DRYAD

Performance (survival and reproduction) in spider colonies of different personality compositions exposed to different temperature treatments. Data includes the number of egg cases produced by each colony