Associations of dispersal traits with fecundity and clonal expansion among Japanese ant-dispersed sedges

Dispersal syndrome, which describe covariation of dispersal traits with other traits, provide clues for potential selection pressures or evolutionary constraints imposed on dispersal. In plants, theory predicts various associations of dispersal traits with fecundity and clonal expansion, but dispersal syndromes involving these reproductive traits are empirically underexplored. This study examined the associations of two dispersal traits (elaiosome size, autochorous distance) with two reproductive traits (fecundity, clonal expansion) among 40 sedges species (Carex spp.), that disperse seeds through autochory, specifically postfloral stalk bending and growth, followed by myrmecochory. Of the two dispersal traits, longer autochorous distances are expected to reduce local seed clumping, while larger elaiosomes are known to result in longer dispersal distances through attraction of large ants. The PCA analysis using all dispersal and reproductive traits followed by the cluster analysis revealed three groups of sedge species. Of these, group 1 appears to be specialized for longer myrmecochorous distances, and consists of phalanx species with large elaiosome, low fecundity, and short autochorous distance. The other two groups appear to be more specialized for short-distance dispersal with local scattering by means of either the combination of long autochorous distance and high fecundity (group 2) or the clonal expansion (group 3). These trait association is consistent with the functional redundancy of the traits in risk spreading and/or the fecundity cost of producing larger elaiosomes. Moreover, the finding is among the first to show an existence of dispersal syndromes among myrmecochorous plants involving dispersal and reproductive traits.