2017 ESA Annual Meeting (August 6 -- 11)

PS 37-94 - Age-and-stage based demography of a perennial plant

Wednesday, August 9, 2017
Exhibit Hall, Oregon Convention Center
H. Maria Baden1,2, Danielle Sherman1,2, Loic Schneider3, Kim Lundgreen1, Owen Jones1,4, Deborah Roach5, Fritz Schweingruber3 and Johan P. Dahlgren1,2, (1)Department of Biology, University of Southern Denmark, Odense, Denmark, (2)Max-Planck Odense Center on the Biodemography of Aging, University of Southern Denmark, Odense, Denmark, (3)Landscape Dynamics, Eidg. Forschungsanstalt für Wald, Schnee und Landschaft WSL, Birmensdorf, Switzerland, (4)Interdisciplinary Center on Population Dynamics, University of Southern Denmark, Odense, Denmark, (5)Department of Biology, University of Virginia, Charlottesville, VA
Background/Question/Methods

Classic evolutionary theory predicts all organisms will face demographic senescence; a gradual decrease in fertility and an increased risk of death with an advancing age after reaching sexual maturity. Natural selection is believed to not have counteracted the physiological deterioration leading to this senescence with repairs, because at older ages, individuals have increasingly smaller portions of their lifetime reproductive output left. This would lead to a decrease in the force of selection over life spans and allow accumulation of deleterious mutations or favor pleiotropic genes conferring fitness advantages to young individuals at the expense of lower late-life fitness. However, it is not clear whether assumptions of these theoretical predictions hold for plants, and in addition, very little detailed age-based demographic data is available for plants. Understanding how plants age is not only interesting to advance the understanding of the evolution of demographic senescence, but will also be useful to improve forecasting efforts that aim to assess population viability. We address this knowledge gap by combining the underutilized technique of age determination of herbs through annual growth increments derived via root histology and polarization microscopy, with detailed demographic monitoring.

Results/Conclusions

We present preliminary results of three years of individual-level age + size demographic data for the herbaceous perennial Plantago lanceolata L. (Plantaginaceae) from Denmark. Age was determined from the annual growth increments caused by production of large xylem vessels early in the season, and we illustrate how the precise height of the cut in the root collar plays a crucial role in determining the actual age of the individual. The results elucidate the impact of size and age on survival, reproduction and individual growth in this population, as well as their impact on population growth rate. We also present age-distributions from four locations with differing resource availabilities and discuss what these distributions suggest regarding age-dependent mortality. Our preliminary results show how age may be important to account for when attempting to understand the demography of plants.