Evolving social dynamics prime thermal tolerance during a poleward range shift

Abstract

Cold tolerance plays a critical role in determining the geographical range limits of species. Previous studies have found that range shifts in response to climate warming are facilitated, paradoxically, by cold acclimation capacities, due to increasingly colder and variable weather at high latitudes. However, the evolutionary dynamics of this process are poorly understood. In this study we combined experiments and field studies to investigate the social and ecological factors affecting cold tolerances in range-shifting populations of the female-polymorphic damselfly Ischnura elegans in northeast Scotland, and their consequences for evolutionary change. In the field, we observed both environmental and social effects on cold tolerance and female colour morph frequencies. This process results in a latitudinal cline in female morph frequencies, due to positive feedback between social stress and thermal tolerances. Density manipulations in the laboratory provide experimental evidence that social interactions directly impact cold tolerance. Reciprocal effects of social environments on thermal acclimation may be important but commonly overlooked aspects of allee effects that contribute to the formation of range margins. Moreover, there is a wider need to consider the role of evolving social dynamics to reciprocally shape both the thermal physiology of individuals and the thermal niches of species.

Evolution of cold tolerance and thermal plasticity in life history, behaviour and physiology during a poleward range expansion

“…In both the Swedish and Scottish range expansion regions the adults show an increased cold tolerance consistent with the lower minimum temperatures in these regions (Lancaster et al, 2015(Lancaster et al, , 2016Wood et al, 2019). Instead, in both expansion regions the heat tolerance did not change, which may reflect relaxed selection on this trait (Kolbe et al, 2014;Krehenwinkel & Tautz, 2013;Lancaster et al, 2015Lancaster et al, , 2016Wood et al, 2019). While providing very interesting insights, studies so far have directly phenotyped field-collected animals precluding making inferences whether these patterns were reflecting thermal plasticity or thermal adaptation.…”

“…The range expansion in Sweden has been associated with allele frequency changes in relation to environmental variables like summer temperature, annual precipitation and wind speed (Dudaniec et al, 2018). In both the Swedish and Scottish range expansion regions the adults show an increased cold tolerance consistent with the lower minimum temperatures in these regions (Lancaster et al, 2015(Lancaster et al, , 2016Wood et al, 2019). Instead, in both expansion regions the heat tolerance did not change, which may reflect relaxed selection on this trait (Kolbe et al, 2014;Krehenwinkel & Tautz, 2013;Lancaster et al, 2015Lancaster et al, , 2016Wood et al, 2019).…”

Network resilience

“…Those are also within the scope of this chapter. Most often, the studies in this area include the foraging behavior [540,541], nest building [542], and copying with stresses [543,544]. The resilience of social insects depends on three crucial elements of such system infrastructure: transportation networks, supply chains, and communication networks [545].…”

“…Inversely, researchers of social insects may benefit from adopting the sophisticated analytical and simulation tools developed for the study of human infrastructure resilience. The essential difference between the two design strategies is that unlike in human social systems, the change in animal social systems [540,544] can come only via evolving the particular species social dynamics.…”

“…Figure 63 Experiments and field studies were combined in Ref. [544] to investigate the social and ecological factors affecting cold tolerances in range-shifting populations of the female-polymorphic damselfly Ischnura elegans in northeast Scotland. The range-shifting, i.e., the poleward shifts in geographical ranges, happen when the climate warms, and the geographical position of some species thermal range limit changes with it, and they expand their range to fill these new thermal boundaries.…”