High dispersal ability is related to fast life-history strategies

1. Seed dispersal is an essential, yet often overlooked process in plant ecology and evolution, affecting adaptation capacity, population persistence and invasiveness. A species' ability to disperse is expected to covary with other life-history traits to form dispersal syndromes. Dispersal might be linked to the rate of life history, fecundity or generation time, depending on the relative selection pressures of bethedging, kin competition or maintaining gene flow. However, the linkage between dispersal and plant life-history strategies remains unknown because it is difficult to observe, quantify and manipulate the influence of dispersal over large spatio-temporal scales. 2. We integrate datasets describing plant vital rates, dispersal and functional traits to incorporate dispersal explicitly into the rich spectra of plant life-history strategies. For 141 plant species, we estimated dispersal ability by predicting maximum dispersal distances using allometric relationships based on growth form, dispersal mode, terminal velocity and seed mass. We derived life-history traits from matrix population models parameterized with field data from the COMPADRE Plant Matrix Database. We analysed the covariation in dispersal ability and life-history traits using multivariate techniques. 3. We found that three main axes of variation described plant dispersal syndromes: the fast-slow life-history continuum, the dispersal strategy axis and the reproductive strategy axis. On the dispersal strategy axis, species' dispersal abilities were positively correlated with aspects of fast life histories. Species with a high net reproductive rate, a long window of reproduction, low likelihood of escaping senescence and low shrinkage tendencies disperse their seeds further. The overall phylogenetic signal in our multidimensional analyses was low (Pagel's lambda < 0.24), implying a high degree of taxonomic generality in our findings. 4. Synthesis. Dispersal has been largely neglected in comparative demographic studies, despite its pivotal importance for populations. Our explicit incorporation of dispersal in a comparative life-history framework provides key insights to bridge the gap between dispersal ecology and life-history traits. Species with fast life-history strategies disperse their seeds further than slow-living plants, suggesting that longer dispersal distances may allow these species to take advantage of habitats varying unpredictably in space and time as a bet-hedging strategy.