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Creators/Authors contains: "Muir, Christopher D."

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  1. ; ; ; ; ; ( , AoB PLANTS)
    Hauck, Markus (Ed.)
    Abstract Plant ecophysiology is founded on a rich body of physical and chemical theory, but it is challenging to connect theory with data in unambiguous, analytically rigorous and reproducible ways. Custom scripts written in computer programming languages (coding) enable plant ecophysiologists to model plant processes and fit models to data reproducibly using advanced statistical techniques. Since many ecophysiologists lack formal programming education, we have yet to adopt a unified set of coding principles and standards that could make coding easier to learn, use and modify. We identify eight principles to help in plant ecophysiologists without much programming experience to write resilient code: (i) standardized nomenclature, (ii) consistency in style, (iii) increased modularity/extensibility for easier editing and understanding, (iv) code scalability for application to large data sets, (v) documented contingencies for code maintenance, (vi) documentation to facilitate user understanding; (vii) extensive tutorials and (viii) unit testing and benchmarking. We illustrate these principles using a new R package, {photosynthesis}, which provides a set of analytical and simulation tools for plant ecophysiology. Our goal with these principles is to advance scientific discovery in plant ecophysiology by making it easier to use code for simulation and data analysis, reproduce results and rapidly incorporate new biological understanding and analytical tools. 
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  2. ; ; ; ; ; ( , New Phytologist)
    Summary

    Habitat restoration may depend on the recovery of plant microbial symbionts such as arbuscular mycorrhizal (AM) fungi, but this requires a better understanding of the rules that govern their community assembly.

    We examined the interactions of soil and host‐associated AM fungal communities between remnant and restored patches of subtropical montane forests.

    While AM fungal richness did not differ between habitat types, community membership did and was influenced by geography, habitat and host. These differences were largely driven by rare host‐specific AM fungi that displayed near‐complete turnover between forest types, while core AM fungal taxa were highly abundant and ubiquitous. The bipartite networks in the remnant forest were more specialized and hosts more specific than in the restored forest. Host‐associated AM fungal communities nested within soil communities in both habitats, but only significantly so in the restored forest.

    Our results provide evidence that restored and remnant forests harbour the same core fungal symbionts, while rare host‐specific taxa differ, and that geography, host identity and taxonomic resolution strongly affect the observed distribution patterns of these fungi. We suggest that host‐specific interactions with AM fungi, as well as spatial processes, should be explicitly considered to effectively re‐establish target host and symbiont communities.

     
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  3. ; ; ; ; ; ; ( , American Journal of Botany)
    Premise

    Across taxa, vegetative and floral traits that vary along a fast‐slow life‐history axis are often correlated with leaf functional traits arrayed along the leaf economics spectrum, suggesting a constrained set of adaptive trait combinations. Such broad‐scale convergence may arise from genetic constraints imposed by pleiotropy (or tight linkage) within species, or from natural selection alone. Understanding the genetic basis of trait syndromes and their components is key to distinguishing these alternatives and predicting evolution in novel environments.

     Methods

    We used a line‐cross approach and quantitative trait locus (QTL) mapping to characterize the genetic basis of twenty leaf functional/physiological, life history, and floral traits in hybrids between annualized and perennial populations of scarlet monkeyflower (Mimulus cardinalis).

     Results

    We mapped both single and multi‐trait QTLs for life history, leaf function and reproductive traits, but found no evidence of genetic co‐ordination across categories. A major QTL for three leaf functional traits (thickness, photosynthetic rate, and stomatal resistance) suggests that a simple shift in leaf anatomy may be key to adaptation to seasonally dry habitats.

     Conclusions

    Our results suggest that the co‐ordination of resource‐acquisitive leaf physiological traits with a fast life‐history and more selfing mating system results from environmental selection rather than functional or genetic constraint. Independent assortment of distinct trait modules, as well as a simple genetic basis to leaf physiological traits associated with drought escape, may facilitate adaptation to changing climates.

     
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  4. ; ; ; ; ; ( , New Phytologist)
    Summary

    Leaf optical properties impact leaf energy balance and thus leaf temperature. The effect of leaf development on mid‐infrared (MIR) reflectance, and hence thermal emissivity, has not been investigated in detail.

    We measured a suite of morphological characteristics, as well as directional‐hemispherical reflectance from ultraviolet to thermal infrared wavelengths (250 nm to 20 µm) of leaves from five temperate deciduous tree species over the 8 wk following spring leaf emergence.

    By contrast to reflectance at shorter wavelengths, the shape and magnitude of MIR reflectance spectra changed markedly with development. MIR spectral differences among species became more pronounced and unique as leaves matured. Comparison of reflectance spectra of intact vs dried and ground leaves points to cuticular development – and not internal structural or biochemical changes – as the main driving factor. Accompanying the observed spectral changes was a drop in thermal emissivity from about 0.99 to 0.95 over the 8 wk following leaf emergence.

    Emissivity changes were not large enough to substantially influence leaf temperature, but they could potentially lead to a bias in radiometrically measured temperatures of up to 3 K. Our results also pointed to the potential for using MIR spectroscopy to better understand species‐level differences in cuticular development and composition.

     
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  5. ; ; ; ; ; ; ; ; ; ; et al ( , Global Change Biology)
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