Life and death in a Petersham cemetery: The demography of potentially immortal organisms

Background/Question/Methods

Most filamentous fungi are assumed to be asenescent, but there are scarcely any data to test the hypothesis. An avoidance of senescence may hinge on the demographic trajectories experienced by populations in the wild. In October 2005 I began a survey of Xanthoparmelia lichens growing on tombstones of a New England Cemetery. Each year I record births and deaths, along with growth rates of established individuals, and I am currently tracking near to 1,000 individuals. 

Results/Conclusions

Preliminary analyses suggest reproduction increases with the size and age of an individual, and although lichens experience “infant” mortality, as lichens grow larger and older the probability of death does decrease. The life history patterns of these modular, indeterminate organisms may be poorly served by traditional demographic models.