Self-organization in the dynamics of huddling behavior in Octodon degus in two contrasting seasons

Abstract

Artículo de publicación ISIIn small mammals, huddling appears as an efficient response to low temperature with important consequences in energy saving, which in turn affect individual fitness. It has been proposed that this behavior is a self-organized process. However, to prove self-organization, it is necessary to study the dynamics of huddling, ruling out the presence of leaders. The objectives of this study were to determine the dynamics of huddling at different temperatures in Octodon degus, documenting the presence or absence of leaders, and to study the consistency of this behavior in two contrasting seasons. We found that huddling dynamics did not indicate the presence of leader initiators of the clustering at lower temperatures. There was no deterministic pattern in huddling dynamics, in any period or at any temperature, suggesting a behavior triggered spontaneously without any order, hierarchy, or recipes. The effect of temperature on huddling behavior was marked and similar in both seasons. The variability of the huddled groups was greater at higher temperatures, which is explained by a greater movement of individuals and more frequent variations in the number and size of the groups at higher temperatures. The results describe huddling as a self-organized behavior, more economical than other physiological processes and therefore preserved by natural selection. This increases its importance for survival and fitness given the significant reduction in energy expenditure achieved under conditions of low temperatures and reduced availability of food, such as during the breeding season of O. degus

Self-organised criticality in the evolution of a thermodynamic model of rodent thermoregulatory huddling

“…The Monte Carlo algorithm presented here uses the standard method of Gibbs sampling, which is described next in terms of huddling interactions. The description of huddling is based only on a description of the litter in terms of the sizes of its component groups (or ‘aggregons’ [ 4 , 14 , 15 ]), and abstracts the dynamics of real huddling, however it captures the idea that when two pups come into contact they will either stay in contact (if doing so is energetically favourable), or one will avoid the other and so be displaced from its group.…”

“…In cold environments, huddling together is a ‘good trick’ that is exploited by many endothermic species in order to keep warm. Huddling in many species of mammals and birds has been described as a self-organising system [ 1 – 4 ], whereby simple local interactions between individual animals collectively give rise to a complex group-level behaviour. The huddle constitutes an adaptive thermoregulatory system in which the interaction between self-organisation and natural selection, two forces that shape all biological systems, may be expressed in terms of a common (metabolic) currency.…”

Modelling the emergence of rodent filial huddling from physiological huddling

“…Bats huddle to compensate for poor insulation in forest roosting sites, and huddling is important for the initiation and maintenance of group cohesion during collective roost-switching behaviours [ 4 ]. Other rodents, including mice [ 5 ], rats [ 6 ], rabbits [ 7 ] and degus [ 8 ], huddle to insulate from the cold, by collectively reducing the exposed surface-area-to-volume ratio of the group [ 9 , 10 ]. And social thermoregulation in primates (bamboo lemurs) has recently been shown to be more important for temperature homeostasis than the choice of resting site [ 11 ].…”

“…Bats huddle to compensate for poor insulation in forest roosting sites, and huddling is important for the initiation and maintenance of group cohesion during collective roost-switching behaviours [4]. Other rodents, including mice [5], rats [6], rabbits [7] and degus [8], huddle to insulate from the 2017 The Authors. Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited.…”

“…This is due to their prevalence as laboratory species, and to the precision with which the thermal physiology of these species has been investigated [12,13]. A number of agent-based computer models [5,8,[14][15][16][17][18][19][20] have been formulated to describe how rodent huddling behaviours at the level of the group emerge from simple rules of interaction between individuals [5,6,21,22].…”