University of British Columbia New Haven, Connecticut, Canada
Background/Question/Methods Variability in the environment defines the structure and dynamics of all living systems, from cells to organisms to ecosystems. Species have evolved traits and strategies that allow them to detect, exploit and predict the changing environment. These traits allow organisms to maintain steady internal conditions required for physiological functioning through feedback mechanisms that allow internal conditions to remain at or near a set point despite a fluctuating environment. In addition to feedback, many organisms have evolved cue-based feedforward processes, which allow them to adjust in anticipation of an expected future state of the environment. Although the significance of cue use has been well documented in a large number of species and contexts, these studies have typically been done on a species-by-species basis, and we lack a coherent understanding of cue use as a universal biological phenomenon. Here I provide a framework and data describing how cue-based feedforward mechanisms operating within organisms can generate effects across scales of biological organization, and how they allow living systems to persist in fluctuating environments.
Results/Conclusions I demonstrate how daily, seasonal and multi-year cycles provide cues that organisms use to anticipate changes in physiologically-relevant environmental conditions. Using feedforward mechanisms, organisms can exploit correlations in environmental variables to prepare for anticipated future changes. Strategies to obtain, store and act on information about the conditional nature of future events are advantageous and are evidenced in widespread phenotypes such as circadian clocks, social behaviour, diapause, and migrations. I demonstrate the importance of established cues like temperature, photoperiod and precipitation, but also identify unexpected environmental variables such as snowpack and wind speed that disproportionately contribute to cuescapes. Notably, findings indicate that climate change will differentially impact the reliability of different cues used by different species with consequences for community change. Finally, I show how humans are altering the ways in which the environment fluctuates, causing correlations between environmental variables to become decoupled, decreasing the reliability of cues. Human-induced environmental change is also altering sensory environments and the ability of organisms to detect cues. Recognizing that living systems combine feedback and feedforward processes is essential to understanding their responses to current and future regimes of environmental fluctuations.
