Our current understanding of late mortality patterns may be limited by the experimental conditions under which they have been studied. This project is designed to expand our understanding about the process of senescence to species in its natural environment and to a possible new model system for aging using a plant species. This study, with Plantago lanceolata, is the largest demographic study of a species in its natural environment.
The specific aims of this application include the following: to determine whether this species, shows age-dependent mortality, either in its natural environment or under controlled conditions; to quantify the genetic contribution to mortality patterns in a natural environment; and to use longitudinal data from a large number of individuals to link the lifecourse dynamics of individuals together with the population-level mortality patterns. The preliminary results from this study suggest that in a natural environment, mortality is very high and it shows seasonal and yearly variation. The analysis to date shows that, in the natural population, the largest individuals have the greatest reproductive output and the lowest mortality. The preliminary conclusion is that this species, that shows continued growth after reproductive maturity, may be able to escape the aging processes. Considerably more demographic analysis is required to verify this hypothesis. Additional analysis is planned to evaluate the importance of cohort history to the mortality dynamics, to link the longitudinal history of individuals with the mortality patterns, to determine if there is any evidence for a physiological decline associated with aging, and to determine how family and spatial location influence the mortality dynamics. One of the interesting results from this experiment is that under controlled conditions, individuals live significantly longer than they do in natural conditions, and the mortality patterns are very plastic. Future results will show whether this species shows age-dependent mortality at extremely late ages under these controlled conditions. This application requests 1.5 years of additional funding to support the continuation of the experiments and the analysis of the results.
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