The thermal environment as a moderator of social evolution

Abstract

Animal sociality plays a crucial organisational role in evolution. As a result, understanding the factors that promote the emergence, maintenance, and diversification of animal societies is of great interest to biologists. Climate is among the foremost ecological factors implicated in evolutionary transitions in social organisation, but we are only beginning to unravel the possible mechanisms and specific climatic variables that underlie these associations. Ambient temperature is a key abiotic factor shaping the spatio‐temporal distribution of individuals and has a particularly strong influence on behaviour. Whether such effects play a broader role in social evolution remains to be seen. In this review, we develop a conceptual framework for understanding how thermal effects integrate into pathways that mediate the opportunities, nature, and context of social interactions. We then implement this framework to discuss the capacity for temperature to initiate organisational changes across three broad categories of social evolution: group formation, group maintenance, and group elaboration. For each category, we focus on pivotal traits likely to have underpinned key social transitions and explore the potential for temperature to affect changes in these traits by leveraging empirical examples from the literature on thermal and behavioural ecology. Finally, we discuss research directions that should be prioritised to understand the potentially constructive and/or destructive effects of future warming on the origins, maintenance, and diversification of animal societies.

A warmer environment can reduce sociability in an ectotherm

“…A recent review by Moss and While ( 2021 ) concluded that ‘we lack empirical evidence that explicitly tests the effects of temperature on social behaviour’. Here, we provide evidence for a causal effect of rearing temperature on social behaviour.…”

“…Yet, we still saw reduced sociability in fish reared at a higher temperature over two generations, regardless of their thermal habitat of origin (Figure 5 ). This suggests that the effects of temperature on sociability are at least partially mediated through intrinsic pathways, such as physiological or endocrine changes that occur throughout development (Moss & While, 2021 ), although it is worth noting that we also cannot eliminate the possible contribution of parental and other epigenetic effects from the F1 generation (Fuxjäger et al, 2019 ).…”

“…Understanding the potential relationship between temperature and social behaviour is especially important in light of global climate change (Moss & While, 2021 ). Even though rising temperatures could have profound consequences for the maintenance and diversification of social organization, these effects remain unknown and underappreciated (Moss & While, 2021 ).…”

“…Understanding the potential relationship between temperature and social behaviour is especially important in light of global climate change (Moss & While, 2021 ). Even though rising temperatures could have profound consequences for the maintenance and diversification of social organization, these effects remain unknown and underappreciated (Moss & While, 2021 ). So far, the few studies on this topic have focused on phylogenetic approaches to look at the relationship between past climatic conditions and the occurrence of sociality across closely related species (e.g., Groom & Rehan, 2018 ; Jezovit et al, 2020 ).…”

“…So far, the few studies on this topic have focused on phylogenetic approaches to look at the relationship between past climatic conditions and the occurrence of sociality across closely related species (e.g., Groom & Rehan, 2018 ; Jezovit et al, 2020 ). However, we still lack experimental studies testing whether similar processes could unfold within a single species or population on ecological timescales (Moss & While, 2021 ). In particular, common garden or reciprocal transplant experiments could help us untangle the role of plasticity and local adaptation in mediating changes in sociality in response to temperature variation (Fisher et al, 2021 ).…”