2. How might climate change impact social organization in bees?
Climatic selective pressures have been implicated in social evolutionary transitions across animal taxa (Guevara and Avilés, 2015; Jetz and Rubenstein, 2011; Liu et al., 2020; Lukas and Clutton-Brock, 2017). These patterns support the hypothesis that sociality can facilitate the colonization of unpredictable environments, or can expand species’ ranges (Brooks et al., 2017; Cornwallis et al., 2017). In bees, climatic factors have shaped the diversification and distributions of social lineages (Brady et al., 2006; Groom and Rehan, 2018; Kocher et al., 2014). The same selective forces that have historically shaped the evolution of social behavior in bees could likewise influence social behavior under climate change.
The bees most likely to experience transitions in social organization in response to climate change are facultatively social bees with some degree of social plasticity because they already possess the behavioral flexibility to express multiple social states. Facultative sociality is best known among the Halictidae and Xylocopinae (Michener, 1990; Shell and Rehan, 2017), but may be widespread across bee taxa when one considers communal nesters and the many typically solitary species that may have some capacity for communal nesting (Wcislo and Tierney, 2009). Additionally, climate change may influence colony demography and social traits (e.g., colony size, reproductive skew, sex ratios) across bee species more broadly, including the obligately social species. Importantly, these demographic shifts can impact the social environment, which can in turn promote changes in social organization and complexity (Figure 2).