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Harvard Forest Research Project 2022

  • Title: The DoXL Survey: a Demography of Xanthoparmelia Lichens
  • Principal investigator: Anne Pringle (
  • Institution: University of Wisconsin - Madison
  • Primary contact: Anne Pringle (
  • Team members: Benjamin Wolfe
  • Abstract:

    Different evolutionary hypotheses predict that aging is inevitable, but the assumptions of these hypotheses are not met by filamentous fungi. It is not clear if filamentous fungi senesce. They are potentially immortal. Demographic processes are central to an understanding of senescence; without information on births and deaths patterns of senescence will make little sense. Note that although fungi may be immortal, individuals do not persist in the environment forever. Death may also be caused by mechanical damage or disease. In October 2005 I will initiate a long-term survey of populations of Xanthoparmelia lichens. Lichens are symbioses of fungi and photosynthetic microorganisms but in this work I am focused on the filamentous fungus that encloses the photobiont. By collecting a demography I will be able to answer a series of fundamental questions, including, are birth rates equivalent each year, or is birth much more common in some particularly favorable years? Is the probability of death equivalent at any age, or does the probability of death increase with age? To my knowledget no demographies of fungi have ever been collected from nature. Lichens are an obvious choice of fungus as lichens grow outside of soil and lichen thalli are visible, moreover, lichens do not move and migration can be ignored. The appearance, size, sexual reproductive capacity and death of especially Xanthoparmelia species are easily measured (Pringle et al. 2003), and previous data suggest that individuals do not live for more than a decade (Golm et al. 1993). I have identified four different populations of lichens growing at different cemeteries within the Harvard Forest at Petersham, MA. I aim to 1) assign unique labels to each individual (e.g. individual 1, 2, 3, etc.) 2) record the births of new individuals in every year after the first year 3) record any deaths in every year after the first year 4) trace the perimeter of each lichen in every year. Tracings will be digitized and areas calculated from the tracings. The change in area from year to year will provide information on growth rates. I expect that data for publication will be available by the fifth year of the survey, however, I plan to run the experiment for approximately 20 years.