Phenological asynchrony: a ticking time‐bomb for seemingly stable populations?

Abstract

Climate change has been shown to induce shifts in the timing of life‐history events. As a result, interactions between species can become disrupted, with potentially detrimental effects. Predicting these consequences has proven challenging. We apply structured population models to a well‐characterised great tit‐caterpillar model system and identify thresholds of temporal asynchrony, beyond which the predator population will rapidly go extinct. Our model suggests that phenotypic plasticity in predator breeding timing initially maintains temporal synchrony in the face of environmental change. However, under projections of climate change, predator plasticity was insufficient to keep pace with prey phenology. Directional evolution then accelerated, but could not prevent mismatch. Once predator phenology lagged behind prey by more than 24 days, rapid extinction was inevitable, despite previously stable population dynamics. Our projections suggest that current population stability could be masking a route to population collapse, if high greenhouse gas emissions continue.

The anatomy of a phenological mismatch: interacting consumer demand and resource characteristics determine the consequences of mismatching

“…Using this approach, we built upon the findings of Senner et al (2017) and identified heretofore undetected individual- and population-level fitness effects of mismatching in the Alaskan breeding population of Hudsonian godwits. Our study joins the growing literature suggesting that mismatches do not fall neatly into a ‘matched’ or ‘mismatched’ paradigm (Keogan et al 2020, Simmonds et al 2020). Instead, models built around the underlying biological mechanisms connecting consumers and resources are key to clarifying how mismatching affects consumer fitness (Takimoto and Sato 2020).…”

“…The need to accurately identify mismatches is made most clear by the accumulating evidence for variable and non-linear responses by consumer populations to mismatching (Visser and Both 2005, Phillimore et al 2016). So called ‘tipping points’ – thresholds past which an effect abruptly changes (Latty and Dakos 2019) – buffer consumer populations from the negative impacts of moderate mismatching and may contribute to the lack of consistent responses to mismatching across consumer populations (Simmonds et al 2020). In this population of godwits, we found that greater population-level mismatching consistently drove poorer fledging success, but that there may be thresholds past which the effects are most severe.…”

“…The significant spring warming and earlier snow disappearance dates projected for the North American sub-Arctic, for instance, means that godwits and other migratory populations may soon face accelerating, potentially non-linear warming to which they have limited capacity to respond (Love et al 2010, Lader et al 2020). Quantifying the strength and effects of mismatching in real time will thus be crucial for conservation going forward (Simmonds et al 2020).…”

The effect of resource depletion on the thermal response of mosquito population fitness

“…Studies on the effects of climatic change on resource availability have recently shown how warming could lead to the collapse of consumer populations due to increased phenological asynchrony with resource populations (Simmonds et al 2020). However, while climatic warming is identified as the most important threat to insect populations (Halsch et al 2021), very few field studies have considered how it may indirectly affect food availability.…”

Towards a more precise – and accurate – view of eco‐evolution

“…This feedback loop is combined with development and inheritance functions to drive joint multi‐generational dynamics of traits, demography, population density and selection (Simmonds et al . 2020). When entire distributions of traits and fitness must be studied, then ecological and evolutionary time cannot be separated (Lion 2018).…”