Climate change and unequal phenological changes across four trophic levels: constraints or adaptations?

Abstract

Summary 1.Climate change has been shown to affect the phenology of many organisms, but interestingly these shifts are often unequal across trophic levels, causing a mismatch between the phenology of organisms and their food. 2. We consider two alternative hypotheses: consumers are constrained to adjust sufficiently to the lower trophic level, or prey species react more strongly than their predators to reduce predation. We discuss both hypotheses with our analyses of changes in phenology across four trophic levels: tree budburst, peak biomass of herbivorous caterpillars, breeding phenology of four insectivorous bird species and an avian predator. ) have advanced, whereas raptor hatching dates showed no trend. 4. The caterpillar peak date was closely correlated with budburst date, as were the passerine hatching dates with the peak caterpillar biomass date. In all these cases, however, the slopes were significantly less than unity, showing that the response of the consumers is weaker than that of their food. This was also true for the avian predator, for which hatching dates were not correlated with the peak availability of fledgling passerines. As a result, the match between food demand and availability deteriorated over time for both the passerines and the avian predators. 5. These results could equally well be explained by consumers' insufficient responses as a consequence of constraints in adapting to climate change, or by them trying to escape predation from a higher trophic level, or both. Selection on phenology could thus be both from matches of phenology with higher and lower levels, and quantifying these can shed new light on why some organisms do adjust their phenology to climate change, while others do not.

Earlier breeding, lower success: does the spatial scale of climatic conditions matter in a migratory passerine bird?

“…However, the rate of phenological change may differ considerably depending on the trophic level of a given species (see Both et al. 2009; Thackeray et al. 2010).…”

Phenological asynchrony between herbivorous insects and their hosts: signal of climate change or pre-existing adaptive strategy?

“…Since the Third Assessment Report of the IPCC in 2001, one of the major concerns about biological impacts of recent anthropogenically driven climate change is that they can alter interactions between species in ways which could cascade through communities or even ecosystems (Harrington et al 1999;IPCC 2001IPCC , 2007Visser et al 2004;Cleland et al 2007;Memmott et al 2007;Both et al 2009). One of the reasons for this concern is that recent climaterelated trends have differed among functional groups and trophic levels (figure 1; Parmesan 2007;Thackeray et al 2010).…”

Geographical pattern in first bloom variability and its relation to temperature sensitivity in the USA and China

“…Spring phenology in the continental United States (except the southeastern part) became 4-8 days earlier after 1984 compared to proceeding decades (Schwartz et al 2013a). Except for detecting phenological trends, phenological variability is also noteworthy because some extreme phenological events may lead to critical disturbances and mismatches in ecosystems (Both et al 2009;Lloret et al 2012;Schleip et al 2012).…”