Abstract
Significant changes in plant phenology have been observed in response to increases in mean global temperatures. There are concerns that accelerated phenologies can negatively impact plant populations. However, the fitness consequence of changes in phenology in response to elevated temperature is not well understood, particularly under field conditions. We address this issue by exposing a set of recombinant inbred lines of Arabidopsis thaliana to a simulated global warming treatment in the field. We find that plants exposed to elevated temperatures flower earlier, as predicted by photothermal models. However, contrary to life-history trade-off expectations, they also flower at a larger vegetative size, suggesting that warming probably causes acceleration in vegetative development. Although warming increases mean fitness (fruit production) by ca. 25%, there is a significant genotype-by-environment interaction. Changes in fitness rank indicate that imminent climate change can cause populations to be maladapted in their new environment, if adaptive evolution is limited. Thus, changes in the genetic composition of populations are likely, depending on the species’ generation time and the speed of temperature change. Interestingly, genotypes that show stronger phenological responses have higher fitness under elevated temperatures, suggesting that phenological sensitivity might be a good indicator of success under elevated temperature at the genotypic level as well as at the species level.
Highlights
Flowering time can affect many aspects of a plant’s ecology and fitness (Rathcke & Lacey, 1985; Parra-Tabla & Vargas, 2004; Kover et al, 2009a; Amasino, 2010)
Climate change is expected to have its strongest and most immediate effects on plant phenology (Forrest & Miller-Rushing, 2010; Munguıa-Rosas et al, 2011), and accelerated phenologies have already been observed in many species (Sparks et al, 2000; Abu-Asab et al, 2001; Menzel et al, 2006; Cleland et al, 2012)
We used a climate warming simulation approach and a set of RILs to investigate the effect of small increases in mean temperature on the phenology and fitness of A. thaliana, in a complex environmental background
Summary
Flowering time can affect many aspects of a plant’s ecology and fitness (Rathcke & Lacey, 1985; Parra-Tabla & Vargas, 2004; Kover et al, 2009a; Amasino, 2010). It is hypothesized that plants integrate photoperiod and thermal cues to transition into reproduction once a genetically determined threshold of accumulated photothermal units has been reached These models have been used successfully to study the importance of different mutants and genetic pathways in A. thaliana(Wilczek et al, 2009), and they suggest that for a given site (where the photoperiod is a constant), flowering time should be a linear function of temperature. We used surface-level heating cables (as championed by Grime et al, 2000, 2008) to investigate the effect of temperature on a set of A. thaliana recombinant inbred lines Such climate manipulation under field conditions is powerful because it allows plants to be exposed to small elevations in temperatures without losing information about daily variation in temperature, day length, or other environmental cues, which will be equal across treatments.
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