Longitudinal analysis of Plantago: Age-by-environment interactions reveal aging

• Published in: Ecology (Durham) Vol. 90; no. 6; pp. 1427 - 1433
• Main Authors: Roach, Deborah A, Ridley, Caroline, Dudycha, Jeffry L
• Format: Journal Article
• Language: English
• Published: Washington, DC Ecological Society of America 01-06-2009
• Subjects: Age; age-by-environment interaction; aging; Analysis; Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Botany; cohorts; Demography; Ecology; Environment; Fundamental and applied biological sciences. Psychology; General aspects; Genotypes; Herbs; Inflorescences; longitudinal studies; Mortality; natural population; plant age; Plant ecology; Plant populations; Plantago; Plantago - physiology; Plantago lanceolata; Plants; Population aging; Population Dynamics; Population ecology; senescence; Species; Time Factors; Virginia; Natural population; Plantago lanceolata; Senescence; Interaction; Mortality; age-by-environment interaction; Plantaginaceae; Dicotyledones; Cohort study; Angiospermae; Environment; Spermatophyta; aging; Age; cohorts
• ISSN: 0012-9658; 1939-9170
• DOI: 10.1890/08-0981.1

We know very little about aging (senescence) in natural populations, and even less about plant aging. Demographic aging is identified by an increasing rate of mortality following reproductive maturity. In natural populations, quantifying aging is often confounded because changes in mortality may be influenced by both short- and long-term environmental fluctuations as well as age-dependent changes in performance. Plants can be easily marked and monitored longitudinally in natural populations yet the age-dependent dynamics of mortality are not known. This study was designed to determine whether a plant species, Plantago lanceolata, shows demographic aging in its natural environment. A large, multiple-cohort design was used to separate age-independent and age-dependent processes. Seven years of results show environmental influences on mortality as evidenced by synchronous changes in mortality across four cohorts over time. Age-dependent mortality was found through an age-by-environment interaction when the oldest cohorts had significantly higher mortality relative to the younger cohorts during times of stress. Neither size nor quantity of reproduction could explain this variation in mortality across cohorts. These results demonstrate demographic senescence in a natural population of plants.