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).