Laird, Robert

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https://opus.uleth.ca/handle/10133/3960

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Browsing Laird, Robert by Subject "Aging"

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    Caloric restriction extends lifespan in a clonal plant
    (Wiley, 2024) Chmilar, Suzanne L.; Luzardo, Amanda C.; Dutt, Priyanka; Pawluck, Abbe; Thwaites, Victoria C.; Laird, Robert
    When subjected to dietary caloric restriction (CR), individual animals often outlive well-fed conspecifics. Here, we address whether CR also extends lifespan in plants. Whereas caloric intake in animals comes from ingestion, in plants it derives from photosynthesis. Thus, factors that reduce photosynthesis, such as reduced light intensity, can induce CR. In two lab experiments investigating the aquatic macrophyte Lemna minor, we tracked hundreds of individuals longitudinally, with light intensity—and hence, CR—manipulated using neutral-density filters. In both experiments, CR dramatically increased lifespan through a process of temporal scaling. Moreover, the magnitude of lifespan extension accorded with the assumptions that (a) light intensity positively relates to photosynthesis following Michaelis–Menten kinetics, and (b) photosynthesis negatively relates to lifespan via a power law. Our results emphasize that CR-mediated lifespan extension applies to autotrophs as well as heterotrophs, and suggest that variation in light intensity has quantitatively predictable effects on plant aging trajectories.
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    Offspring of older parents are smaller-but no less bilaterally symmetrical-than offspring of younger parents in the aquatic plant Lemna turionifera
    (Wiley, 2018) Ankutowicz, Eric J.; Laird, Robert A.
    Offspring quality decreases with parental age in many taxa, with offspring of older parents exhibiting reduced life span, reproductive capacity, and fitness, compared to offspring of younger parents. These “parental age effects,” whose consequences arise in the next generation, can be considered as manifestations of parental senescence, in addition to the more familiar age- related declines in parent- generation survival and reproduction. Parental age effects are important because they may have feedback effects on the evolution of demographic trajectories and longevity. In addition to altering the timing of offspring life-history milestones, parental age effects can also have a negative impact on offspring size, with offspring of older parents being smaller than offspring of younger parents. Here, we consider the effects of advancing parental age on a different aspect of offspring morphology, body symmetry. In this study, we followed all 403 offspring of 30 parents of a bilaterally symmetrical, clonally reproducing aquatic plant species, Lemna turionifera, to test the hypothesis that successive offspring become less symmetrical as their parent ages, using the “Continuous Symmetry Measure” as an index. Although successive offspring of aging parents older than one week became smaller and smaller, we found scant evidence for any reduction in bilateral symmetry