Physiological mechanisms underlying animal social behaviour

Abstract

One contribution of 13 to a theme issue 'Physiological determinants of social behaviour in animals'. Many species of animal live in groups, and the group represents the organizational level within which ecological and evolutionary processes occur. Understanding these processes, therefore, relies on knowledge of the mechanisms that permit or constrain group formation. We suggest that physiological capacities and differences in physiology between individuals modify fission -fusion dynamics. Differences between individuals in locomotor capacity and metabolism may lead to fission of groups and sorting of individuals into groups with similar physiological phenotypes. Environmental impacts such as hypoxia can influence maximum group sizes and structure in fish schools by altering access to oxygenated water. The nutritional environment determines group cohesion, and the increase in information collected by the group means that individuals should rely more on social information and form more cohesive groups in uncertain environments. Changing environmental contexts require rapid responses by individuals to maintain group coordination, which are mediated by neuroendocrine signalling systems such as nonapeptides and steroid hormones. Brain processing capacity may constrain social complexity by limiting information processing. Failure to evaluate socially relevant information correctly limits social interactions, which is seen, for example, in autism. Hence, functioning of a group relies to a large extent on the perception and appropriate processing of signals from conspecifics. Many if not all physiological systems are mechanistically linked, and therefore have synergistic effects on social behaviour. A challenge for the future lies in understanding these interactive effects, which will improve understanding of group dynamics, particularly in changing environments.This article is part of the themed issue 'Physiological determinants of social behaviour in animals'.

Cost of transport is a repeatable trait but is not determined by mitochondrial efficiency in zebrafish (Danio rerio)

“…Interestingly, the suggestion that CoT is genetically determined is in line with results from humans, which show that muscle plasticity in response to aerobic training is genetically determined (Bouchard, 2012). Differences in CoT between individuals may contribute to fitness differentials within moving groups, because individuals with a high CoT will have to trade off optimising energy efficiency with staying in the group and gaining the advantages of group living (Krause and Ruxton, 2002;Seebacher and Krause, 2017).…”

“…Interestingly, CoT differs between individuals of the same species (Seebacher et al, 2016). Unless energy-production capacity varies proportionally with CoT, animals from the same population may experience different trade-offs, which can scale up to influence higher level functions such as social behaviour (Killen et al, 2017;Seebacher and Krause, 2017). Understanding the physiological mechanisms that underlie individual differences in CoT will permit predictions about animal behaviour and inform ecological models of animal movement.…”

The Role of Individual Heterogeneity in Collective Animal Behaviour

“…Key is that the spectrum of phenotypic traits seen among grouping animals is strongly hierarchical, with broader sources of phenotypic variation, such as sex and size, comprising more fundamental phenotypic components ( Figure 1A). Additionally, previous work has highlighted the role of individual differences in physiological and motivational processes as a key driving force underlying collective processes [14][15][16]. We build on this knowledge and propose that phenotypic variation can be fundamentally attributed to variation in three physiological components -(i) biomechanics (e.g., muscular ability, mobility), (ii) bioenergetics (e.g., minimum and maximum metabolic rates, aerobic scope), and (iii) neuroendocrinology (e.g., hormone expression and the regulation and activity of certain brain regions; fundamental to emotions) -and (iv) cognitive functioning, which includes sensory acquisition, information processing, knowledge, and learning ability.…”

External and internal grouping characteristics of juvenile walleye pollock in the Eastern Bering Sea

“…Within a group, individuals may position themselves relative to other individuals of similar sizes in response to predator and prey considerations (e.g., Svensson et al, 2000;Maes and Ollevier, 2002). Shifts toward a more favorable group structure are thus the result, in part, of individuals responding to their particular interpretation of the local environment (Bertrand et al, 2006;Gerlotto et al, 2006), filtered through individual internal (e.g., physiology, experience: Seebacher and Krause, 2017;Cantor and Farine, 2018) and external (e.g., fish size: Couzin and Krause, 2003) states. However, not all group behaviors are beneficial; some may be detrimental in specific situations.…”

“…Such "internal heterogeneity" may be indicative of group membership. Relatively high heterogeneity (i.e., higher degree of nuclei and/ or vacuoles) can mean diversity of fish within a group, because individuals of different ages, sizes, or species likely have different physical and physiological limitations (e.g., average or maximum speed, metabolic rates), which can influence the distribution of fish (Grünbaum et al, 2005;Viscido et al, 2007) and induce sorting (Hemelrijk and Kunz, 2005;Seebacher and Krause, 2017). Internal heterogeneity may also be indicative of ecological interactions.…”