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  1. Abdelaziz, Mohamed (Ed.)
    Abstract Individuals within natural populations can experience very different abiotic and biotic conditions across small spatial scales owing to microtopography and other micro-environmental gradients. Ecological and evolutionary studies often ignore the effects of micro-environment on plant population and community dynamics. Here, we explore the extent to which fine-grained variation in abiotic and biotic conditions contributes to within-population variation in trait expression and genetic diversity in natural plant populations. Furthermore, we consider whether benign microhabitats could buffer local populations of some plant species from abiotic stresses imposed by rapid anthropogenic climate change. If microrefugia sustain local populations and communities in the short term, other eco-evolutionary processes, such as gene flow and adaptation, could enhance population stability in the longer term. We caution, however, that local populations may still decline in size as they contract into rare microhabitats and microrefugia. We encourage future research that explicitly examines the role of the micro-environment in maintaining genetic variation within local populations, favouring the evolution of phenotypic plasticity at local scales and enhancing population persistence under global change. 
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  2. Summary

    Plant–herbivore interactions have evolved in response to coevolutionary dynamics, along with selection driven by abiotic conditions. We examine how abiotic factors influence trait expression in both plants and herbivores to evaluate how climate change will alter this long‐standing interaction. The paleontological record documents increased herbivory during periods of global warming in the deep past. In phylogenetically corrected meta‐analyses, we find that elevated temperatures, CO2concentrations, drought stress and nutrient conditions directly and indirectly induce greater food consumption by herbivores. Additionally, elevated CO2delays herbivore development, but increased temperatures accelerate development. For annual plants, higher temperatures, CO2and drought stress increase foliar herbivory. Our meta‐analysis also suggests that greater temperatures and drought may heighten florivory in perennials. Human actions are causing concurrent shifts in CO2, temperature, precipitation regimes and nitrogen deposition, yet few studies evaluate interactions among these changing conditions. We call for additional multifactorial studies that simultaneously manipulate multiple climatic factors, which will enable us to generate more robust predictions of how climate change could disrupt plant–herbivore interactions. Finally, we consider how shifts in insect and plant phenology and distribution patterns could lead to ecological mismatches, and how these changes may drive future adaptation and coevolution between interacting species.

     
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  3. Premise

    Despite myriad examples of local adaptation, the phenotypes and genetic variants underlying such adaptive differentiation are seldom known. Recent work on freezing tolerance and local adaptation in ecotypes ofArabidopsis thalianafrom Italy and Sweden provides an essential foundation for uncovering the genotype–phenotype–fitness map for an adaptive response to a key environmental stress.

    Methods

    We examined the consequences of a naturally occurring loss‐of‐function (LOF) mutation in an Italian allele of the gene that encodes the transcription factorCBF2,which underlies a major freezing‐tolerance locus. We used four lines with a Swedish genetic background, each containing aLOFCBF2allele. Two lines had introgression segments containing the ItalianCBF2allele, and two contained deletions created usingCRISPR‐Cas9. We used a growth chamber experiment to quantify freezing tolerance and gene expression before and after cold acclimation.

    Results

    Freezing tolerance was lower in the Italian (11%) compared to the Swedish (72%) ecotype, and all four experimentalCBF2LOFlines had reduced freezing tolerance compared to the Swedish ecotype. Differential expression analyses identified 10 genes for which allCBF2LOFlines, and theITecotype had similar patterns of reduced cold responsive expression compared to theSWecotype.

    Conclusions

    We identified 10 genes that are at least partially regulated byCBF2that may contribute to the differences in cold‐acclimated freezing tolerance between the Italian and Swedish ecotypes. These results provide novel insight into the molecular and physiological mechanisms connecting a naturally occurring sequence polymorphism to an adaptive response to freezing conditions.

     
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