The role of timing in the ecology of intraspecific trait variation in plants

Olivia L. Cope, Dept. of Entomology, Michigan State University, East Lansing, MI, William C. Wetzel, Department of Integrative Biology, Michigan State University, East Lansing, MI; Ecology, Evolution, and Behavior Program, Michigan State University, East Lansing, MI; Department of Entomology, Michigan State University, East Lansing, MI, Laura Burkle, Department of Ecology, Montana State University, Bozeman, MT, Jordan R. Croy, Ecology and Evolutionary Biology, University of California, Irvine, Irvine, CA, Kailen A. Mooney, Ecology and Evolutionary Biology, University of California, Ivine, Irvine, CA and Louie H. Yang, Department of Entomology and Nematology, University of California, Davis, Davis, CA

Background/Question/Methods
Ontogeny, or plant development through time, has emerged as a key axis of variation in plant traits such as defenses and nutrients and in related species interactions. It is therefore likely that a substantial portion of observed intraspecific trait diversity is due to variation among plants in the timing of life stages. However, this variation typically goes unmeasured or overlooked in community genetics and other intraspecific diversity research. And although there is growing interest in phenological variation and mismatch among species, within-species variation in developmental timing is poorly understood. A crucial question therefore remains unanswered: what is the role of timing, and particularly of the relative timing of plant ontogeny, in the ecology of intraspecific trait variation? We aim to integrate concepts from both community genetics and phenology research into a more holistic framework and research agenda regarding the contribution of timing differences to intraspecific plant diversity and its effects.
Results/Conclusions
Our conceptual analysis of intraspecific trait diversity arising from variation in plant ontogeny, as dictated by relative phenology, reveals two main findings. First, with phenological variation among plants, populations can differ in observed intraspecific trait diversity even without any difference in underlying genotypic composition. Second, timing-based patterns of trait diversity are qualitatively different in their ecological effects than static spatial patterns of trait diversity, because the former interact with the temporal nature of community assembly and species interactions. These are especially urgent considerations given that ontogenetic stage structure is likely to respond rapidly to climate change, even within fixed populations, as the weather patterns driving plant phenology change and destabilize. Rigorous consideration of timing in community genetics may also clarify the conclusions of past single-survey studies and reveal new, temporally explicit patterns of community composition.