Abstract
One consequence of rising spring temperatures is that the optimum timing of key life-history events may advance. Where this is the case, a population's fate may depend on the degree to which it is able to track a change in the optimum timing either via plasticity or via adaptation. Estimating the effect that temperature change will have on optimum timing using standard approaches is logistically challenging, with the result that very few estimates of this important parameter exist. Here we adopt an alternative statistical method that substitutes space for time to estimate the temperature sensitivity of the optimum timing of 22 plant species based on >200000 spatiotemporal phenological observations from across the United Kingdom. We find that first leafing and flowering dates are sensitive to forcing (spring) temperatures, with optimum timing advancing by an average of 3days °C-1 and plastic responses to forcing between -3 and -8days °C-1 . Chilling (autumn/winter) temperatures and photoperiod tend to be important cues for species with early and late phenology, respectively. For most species, we find that plasticity is adaptive, and for seven species, plasticity is sufficient to track geographic variation in the optimum phenology. For four species, we find that plasticity is significantly steeper than the optimum slope that we estimate between forcing temperature and phenology, and we examine possible explanations for this countergradient pattern, including local adaptation.
Highlights
Shifts in phenology are among the most widely reported ecological responses to changing climate across different ecosystems and taxa (Walther et al, 2002; Parmesan & Yohe, 2003; Settele et al, 2014)
In more than half of species, we find that plasticity is adaptive and leads to populations tracking temperaturemediated variation in the optimum more closely than they would in the absence of plasticity (|B-b| < |B|)
The plastic response was significantly steeper and more negative than B, which is consistent with countergradient variation in the optimum timing (Conover & Schulz, 1995; Phillimore et al, 2012)
Summary
Shifts in phenology are among the most widely reported ecological responses to changing climate across different ecosystems and taxa (Walther et al, 2002; Parmesan & Yohe, 2003; Settele et al, 2014). Analysis of the resultant longitudinal data sets reveals that spring phenology has advanced in many species over the past few decades, coincident with rising temperatures (Fitter & Fitter, 2002; Amano et al, 2010; Thackeray et al, 2016). Some of the advancement in phenology will be due to microevolutionary change (Franks et al, 2014), but plastic responses to temperature probably dominate (Nicotra et al, 2010). Temperate plants often exhibit pronounced temperature-mediated plasticity in their spring phenology, as documented via longitudinal studies of individuals (Vitasse et al, 2010; www.trackatree.org.uk), geographic. B is used to map a temporal change in temperature to a temporal change in the optimum. Temperatures vary in space and we can map
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
