A genetic analysis of hydrologically dispersed seeds of Hibiscus moscheutos (Malvaceae)

The dispersal of floating seeds in wetland habitats should influence the ge netic characteristics of plant metapopulations. we examined gene how of a h ydrochorous wetland macrophyte, Hibiscus moscheutos L. (Malvaceae), by anal yzing allozyme variation in current-year Boating-seed populations. The gene tic composition of Rooting seeds was compared to the genetic composition of established populations of H. moscheutos that had been previously analyzed in the same areas. The F statistics demonstrated that genetic structuring among floating-seed populations was weak or absent, indicating that seeds f rom source populations were thoroughly mixed. Floating-seed populations had an excess of homozygotes. a different situation than had previously been f ound in established populations. The exchange of seeds was greatest among H . moscheutos populations that were adjacent to a tidal stream. We conclude that populations adjacent to the tidal streams are part of a metapopulation that serves as a reserve of genetic variation in the system. Although esta blished populations of H. moscheutos that are not close to the tidal stream are relatively isolated genetically, we found evidence that they also cont ribute to the floating-seed population within the estuary.