Dispersal and establishment traits provide a colonization advantage for a polyploid apomictic plant

Premise: Apomictic plants (reproducing asexually through seed) often have larger ranges and occur at higher latitudes than closely related sexuals, a pattern known as geographical parthenogenesis (GP). Explanations for GP include differences in colonizing ability due to reproductive assurance and direct/indirect effects of polyploidy (most apomicts are polyploid) on ecological tolerances. While life history traits associated with dispersal and establishment also contribute to the potential for range expansion, few studies compare these traits in related apomicts and sexuals. 
Methods: We investigated differences in early life history traits between diploid-sexual and polyploid-apomictic Townsendia hookeri (Asteraceae), which displays a classic pattern of GP. Using lab and greenhouse experiments, we measured seed dispersal traits, germination success, and seedling size and survival in sexual and apomictic populations from across the range. 
Key Results: While theory predicts that trade-o..., Study system
Townsendia hookeri is a diminutive perennial member of the sunflower family (Asteraceae) with two forms: diploids that reproduce sexually and autopolyploids (mainly triploids) that reproduce via gametophytic apomixis (Beaman1957; Thompson and Whitton 2006). Sexual individuals are self-incompatible, while apomicts set seed autonomously, without the need for pollen to fertilize the endosperm. Townsendia hookeri produces single-seeded diaspores with persistent feathery pappus bristles (Strother 1993) usually associated with wind dispersal (Andersen 1992). Despite differing in ploidy and reproductive mode, the two forms are macro-morphologically indistinguishable in the field but can be distinguished by pollen traits. Polyploids produce larger viable pollen grains than diploids and have much lower pollen viability. To date, our lab group has characterized more than 90 populations throughout the species’ range and found a tight association between low pollen viability and larger...,