When species are subject to population bottlenecks arising through multiple factors, each factor can contribute to self-incompatibility loss. In a widespread polyploid complex, the loss of self-incompatibility can be predicted by the cumulative effects of whole-genome duplication and intercontinental dispersal.

1. Little is known about plant age-dependent trait expression and how environmental conditions might affect ageing in the wild. This study evaluates age variation in multiple traits of a short-lived perennial herb using a manipulative field experimental design.2. Two different-aged cohorts were followed in a field plot for over a year to evaluate trait expression in response to a competition treatment and seasonal stress. Traits measured included size, mortality, reproduction, and physiology, including photosynthetic efficiency and chlorophyll content (SPAD). We hypothesized that the stress of competition and seasonal changes would accentuate age-dependent trait declines in older plants.3. The results highlight consistent age differences in plant size, mortality, and seed size with older plants being smaller, more likely to die, and producing smaller seeds. Some of the ageing declines were sensitive to environmental conditions such that it was only during certain seasons when older plants had higher mortality, lower photosynthetic efficiency, and lower chlorophyll content than young plants. Age-dependent trait expression also varied in response to competition such that age differences in size were only present in the "no competition treatment," and old individuals in the competition treatment had a higher mortality than all other age-environment combinations. 4. Synthesis. These findings show that ageing in plants is a complex phenotype where declines in traits are uncoordinated and can be, but are not always, sensitive to environmental conditions. This study shows age-dependent maternal effects on offspring quality which, together with the decline in performance of older individuals, may have impacts on an individual's fitness and on natural population demography. K E Y W O R D S age-dependent trait expression, competition, physiology, plant ageing, plant development and life-history traits, plasticity, seasonal stress | 1411 Journal of Ecology QUARLES Et AL. S U PP O RTI N G I N FO R M ATI O N Additional supporting information may be found online in the Supporting Information section at the end of the article. How to cite this article: Quarles BM, Roach DA. Ageing in an herbaceous plant: Increases in mortality and decreases in physiology and seed mass.

Evolvable traits of organisms can alter the environment those organisms experience. While it is well appreciated that those modified environments can influence natural selection to which organisms are exposed, they can also influence the expression of genetic variances and covariances of traits under selection. When genetic variance and covariance change in response to changes in the evolving, modified environment, rates and outcomes of evolution also change. Here we discuss the basic mechanisms whereby organisms modify their environments, review how those modified environments have been shown to alter genetic variance and covariance, and discuss potential evolutionary consequences of such dynamics. With these dynamics, responses to selection can be more rapid and sustained, leading to more extreme phenotypes, or they can be slower and truncated, leading to more conserved phenotypes. Patterns of correlated selection can also change, leading to greater or less evolutionary independence of traits, or even causing convergence or divergence of traits, even when selection on them is consistent across environments. Developing evolutionary models that incorporate changes in genetic variances and covariances when environments themselves evolve requires developing methods to predict how genetic parameters respond to environments—frequently multifactorial environments. It also requires a population-level analysis of how traits of collections of individuals modify environments for themselves and/or others in a population, possibly in spatially explicit ways. Despite the challenges of elucidating the mechanisms and nuances of these processes, even qualitative predictions of how environment-modifying traits alter evolutionary potential are likely to improve projections of evolutionary outcomes.

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