Changes in seed investment across time and space in high-Andean Compositae

(1) The daisy family has successfully colonised alpine environments due to various traits, including a pappus, a modified calyx that improves dispersal. However, little remains known about investment in seed dispersal or nutrient content. We investigated trade-offs between dispersal and nutritional investment in seeds of high-Andean Compositae. (2) Nutrient investment (seed length) and dispersal investment (pappus to seed length ratio) were assessed in 125 Compositae species recorded across Andean mountain summits. We analysed seed trait changes across time and space using phylogenomics, distribution modelling and community analyses. (3) While 28% of species invest more in nutrient content and 29% in dispersal, 43% had low nutrient and dispersal investment. Seed traits were phylogenetically conserved, with improved dispersal investment in tribes with the highest number of species and whose ancestors originated in Africa during the Oligocene. Higher dispersal investment may have enabled species to cross geographic barriers and colonise the high-Andes. Median community dispersal investment increased with elevation, possibly to compensate for lower air density, while nutrient investment decreased with seasonality, potentially to increase dormancy. (4) Most species-rich tribes have enhanced dispersal investment; however, seed investment strategies are tailored according to their environment, suggesting a diversity of strategies might aid high-Andean colonisation.