Normalized Seed Weight of Three Species of the Genus Peganum L. (Peganaceae Van Tieghem) in Mongolia

摘要

Variation of seed weight of Peganum species is positively correlated with meanseed weight in big populations. It was insignifi cant in small populations, suggestingnormalized seed weight is useful to distinguish the population sizes. Normalizedseed weight is increased with increasing aridity index and precipitation amount inmost sites. Within populations of Peganum harmala, variation of seed weight andnormalized seed weight corresponded to Nei’s diversity index, while within otherspecies, mean seed weight corresponded to Nei’s diversity index. The normalizedseed weight was lowest in human-dispersal species, highest in hydro-dispersalspecies, but it was moderate in wind-human-dispersal species. Low normalized seedweight is associated to species with low genetic diversity, while high normalizedseed weight to species with high genetic diversity. Variation of seed weight wasrelated with precipitation and climatic aridity and genetic diversity within speciesand mean seed weight was with climatic aridity and genetic diversity within species,but normalized seed weight was related with precipitation, climatic aridity andgenetic diversity inter- and within species.