Special Feature New Perspectives in Whole-Plant Senescence
Age, stage and senescence in plants
Article first published online: 24 APR 2013
© 2013 The Authors. Journal of Ecology © 2013 British Ecological Society
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Journal of Ecology
Volume 101, Issue 3, pages 585–595, May 2013
How to Cite
Caswell, H., Salguero-Gómez, R. (2013), Age, stage and senescence in plants. Journal of Ecology, 101: 585–595. doi: 10.1111/1365-2745.12088
- Issue published online: 24 APR 2013
- Article first published online: 24 APR 2013
- Manuscript Accepted: 20 FEB 2013
- Manuscript Received: 23 OCT 2012
- ComPADRe III database;
- matrix population models;
- plant development and life history traits;
- selection gradients;
- stage-structured demography;
- vec-permutation matrix
- Senescence (an increase in the mortality rate or force of mortality, or a decrease in fertility, with increasing age) is a widespread phenomenon. Theories about the evolution of senescence have long focused on the age trajectories of the selection gradients on mortality and fertility. In purely age-classified models, these selection gradients are non-increasing with age, implying that traits expressed early in life have a greater impact on fitness than traits expressed later in life. This pattern leads inevitably to the evolution of senescence if there are trade-offs between early and late performance.
- It has long been suspected that the stage- or size-dependent demography typical of plants might change these conclusions. In this paper, we develop a model that includes both stage- and age-dependence and derive the age-dependent, stage-dependent and age×stage-dependent selection gradients on mortality and fertility.
- We applied this model to stage-classified population projection matrices for 36 species of plants, from a wide variety of growth forms (from mosses to trees) and habitats.
- We found that the age-specific selection gradients within a life cycle stage can exhibit increases with age (we call these contra-senescent selection gradients). In later stages, often large size classes in plant demography, the duration of these contra-senescent gradients can exceed the life expectancy by several fold.
- Synthesis. The interaction of age- and stage-dependence in plants leads to selection pressures on senescence fundamentally different from those found in previous, age-classified theories. This result may explain the observation that large plants seem less subject to senescence than most kinds of animals. The methods presented here can lead to improved analysis of both age-dependent and stage-dependent demographic properties of plant populations.