Chronobiology of interspecific interactions in a changing world

Abstract

Animals should time activities, such as foraging, migration and reproduction, as well as seasonal physiological adaptation, in a way that maximizes fitness. The fitness outcome of such activities depends largely on their interspecific interactions; the temporal overlap with other species determines when they should be active in order to maximize their encounters with food and to minimize their encounters with predators, competitors and parasites. To cope with the constantly changing, but predictable structure of the environment, organisms have evolved internal biological clocks, which are synchronized mainly by light, the most predictable and reliable environmental cue (but which can be masked by other variables), which enable them to anticipate and prepare for predicted changes in the timing of the species they interact with, on top of responding to them directly. Here, we review examples where the internal timing system is used to predict interspecific interactions, and how these interactions affect the internal timing system and activity patterns. We then ask how plastic these mechanisms are, how this plasticity differs between and within species and how this variability in plasticity affects interspecific interactions in a changing world, in which light, the major synchronizer of the biological clock, is no longer a reliable cue owing to the rapidly changing climate, the use of artificial light and urbanization.This article is part of the themed issue 'Wild clocks: integrating chronobiology and ecology to understand timekeeping in free-living animals'.

Two sides of a coin: ecological and chronobiological perspectives of timing in the wild

“…Circadian time-place learning, highlighted in this issue for bees [17], may enable kestrels to optimize their hunting behaviour. This example demonstrates the interactions of biological clocks with abiotic and biotic components of time, underlining the relevance of precise timing mechanisms [32].…”

“…Animals live in a world where the abundance of resources and the incidence of threats fluctuate on daily, seasonal and potentially further temporal scales. In addressing these problems, the field of ecology has focused on the timing of individuals relative to the external environment, and on its consequences at intraspecific and interspecific levels [32,55]. The importance of cyclic repeatable variability in ecological conditions has been realized for a long time, and has been highlighted by phenology studies that reported species-specific patterns, which sometimes were stunningly precise between years [29].…”

“…So far, functional explanations of the often striking rhythmic patterns of animals remain mostly speculative, opening intriguing research questions for ecologists and chronobiologists alike [32]. In some cases, environmental drivers of interspecific diversity of patterns have been identified (reviewed by [56,84]).…”

Temporal partitioning of activity: rising and falling top‐predator abundance triggers community‐wide shifts in diel activity

“…Devils are both predators and highly-adapted scavengers, one of the world's few bone-specialist carnivores (Jones 2003). For example, kestrels Falco tinnunculus match the regular 2-h peaks in vole Microtus arvalis activity (Rijnsdorp et al 1981, Kronfeld-Schor et al 2017) and activity patterns of Cooper's hawk Accipiter cooperii reflects those of their prey (Roth and Lima 2007). Other studies show that predators can time their activity to overlap with peak prey activity.…”

“…Declining predator densities may therefore elicit a more gradual response because persistence of low-cost behaviours can be adaptive even when selection is relaxed (Flecker 1992, Kronfeld-Schor et al 2017. First, the costs associated with increasing top-predator densities (death or injury) are probably much higher than the costs associated with decreasing predator densities (small potential foraging loss).…”