Adult presence augments juvenile collective foraging in social spiders

Divergent foraging strategies between populations of sympatric matrilineal killer whales

In cooperative species, human-induced rapid environmental change may threaten cost-benefit tradeoffs of group behavioral strategies that evolved in past environments. Capacity for behavioral flexibility can increase population viability in novel environments. Whether the partitioning of individual responsibilities within social groups is fixed or flexible across populations is poorly understood, despite its relevance for predicting responses to global change at the population and species levels and designing successful conservation programs. We leveraged bio-logging data from two populations of fish-eating killer whales (Orcinus orca) to quantify patterns of fine-scale foraging movements and their relationships with demography. We reveal striking interpopulation differences in patterns of individual foraging behavior. Females from the endangered Southern Resident (SRKW) population captured less prey and spent less time pursuing prey than SRKW males or Northern Resident (NRKW) females, whereas NRKW females captured more prey than NRKW males. The presence of a calf (≤3 years) reduced the number of prey captured by adult females from both populations, but disproportionately so for SRKW. SRKW adult males with a living mother captured more prey than those whose mother had died, whereas the opposite was true for NRKW adult males. Across populations, males foraged in deeper areas than females, and SRKW captured prey deeper than NRKW. These population-level differences in patterns of individual foraging behavior challenge the existing paradigm that females are the disproportionate foragers in gregarious resident killer whales, and demonstrate considerable variation in the foraging strategies across populations of an apex marine predator experiencing different environmental stressors.

A physiological profile approach to animal temperament: How to understand the functional significance of individual differences in behaviour

Animal behaviour research has experienced a renewed interest in consistent individual differences (i.e. animal personality or temperament). Recent ecological studies have identified environmental conditions that give rise to the development and evolution of temperaments and to fitness-related outcomes of temperament. Additional literature has also described relationships between temperaments and physiological regulation. However, one-to-one relationships between one behavioural trait and one physiological system do not account for co-selection of behavioural and physiological traits, nor the complex signalling among physiological systems. In the current paper, we review the literature on multiple physiological processes associated with temperament, propose temperament-specific physiological profiles, and focus on next steps to understand the functional significance, evolution and maintenance of temperaments. We propose that to understand causes and consequences of temperament we need to characterize integrative physiological profiles associated with different temperaments.

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.

Resting networks and personality predict attack speed in social spiders

Groups of social predators capture large prey items collectively, and their social interaction patterns may impact how quickly they can respond to time-sensitive predation opportunities. We investigated whether various organizational levels of resting interactions (individual, sub-group, group), observed at different intervals leading up to a collective prey attack, impacted the predation speed of colonies of the social spider Stegodyphus dumicola. We found that in adult spiders, overall group connectivity (average degree) increased group attack speed. However, this effect was detected only immediately before the predation event; connectivity between 2 and 4 days before prey capture had little impact on the collective dynamics. Significantly, lower social proximity of the group's boldest individual to other group members (closeness centrality) immediately prior and 2 days before prey capture was associated with faster attack speeds. These results suggest that for adult spiders, the long-lasting effects of the boldest individual on the group's attack dynamics are mediated by its role in the social network, and not only by its boldness. This suggests that behavioural traits and social network relationships should be considered together when defining keystone individuals in some contexts. By contrast, for subadult spiders, while the group maximum boldness was negatively correlated with latency to attack, no significant resting network predictors of latency to attack were found. Thus, separate behavioural mechanisms might play distinctive roles in determining collective outcomes at different developmental stages, timescales, and levels of social organization.