OOS 28-3: The evolution of life history: A meta-analysis of phylogeny and demography in terrestrial plants
Jean H. Burns, University of California, Davis and Tiffany Knight, Washington University.
Background/Question/Methods The goal of evolutionary ecology is to understand the evolution of life history in the context of the selective pressures, including ecological context, that drive it. Demography provides a powerful framework for answering such questions, as it explicitly incorporates life history parameters. Demography evolves in the context of the existing life history of a population, selection pressures of the environment, and the constraints imposed by phylogenetic history. To understand the evolution of demography, we need to understand all of these factors in concert. However, until recently, we have not had either sufficiently detailed demographic data, or sufficiently resolved phylogenies, to adequately address questions about the evolution of demography. Here we present the first examination of demographic and life history evolution in the context of a phylogeny of the angiosperms. We have collected a demographic database of 206 plant species for which demographic matrices are available and have used the seed plant phylogeny available via phylomatic. We used this data to answer questions about the evolution of demography including whether certain life histories select for demographic syndromes.
Results/Conclusions We found that there was a negative correlation between the vital rate elasticity of survival and the vital rate elasticity of growth, consistent with a prediction of life history tradeoffs influencing the evolution of demography. A key question in life history evolution is when to reproduce, and we found several characteristics of demography associated with time to reproduction. The vital rate elasticity of survival was positively correlated with the age of first reproduction and the remaining lifespan at reproductive stage. We also found that iteroparous species exhibited higher elasticities for survival than semelparous species. The phylogenetic and demographic perspective enhance our understanding of life history evolution.