Clonal diversity in the submerged macrophyte Potamogeton pectinatus L. inferred from nuclear and cytoplasmic variation

Genetic variation within a worldwide collection of Potamogeton pectinatus L. was investigated by analyzing randomly amplified polymorphisms of nuclear DNA anti restriction fragment length polymorphisms of chloroplast DNA. Of the 51 plants investigated, 50 exhibited unique multi-locus nuclear genotypes. Analysis of chloroplast DNA revealed four unique haplotypes, as well as distinct cytonuclear genotypes in populations from geographically isolated regions (e.g., Donana, Spain and Pechora Delta, Russia). Based on the distributional pattern of P. pectinatus, previous studies have assumed that dispersal between populations is frequent and genotypes are distributed according to the island model of genetic structure. In contrast, we found that genetic distances and geographic distances were significantly correlated, indicating that the observed population structure can better be explained by stepping stone or isolation by distance models. Although no distinction of historic factors, such as founder effects, and current processes, such as environmental conditions, can be derived from this data set, we found indications for the impact of migrating water-fowl on plant distributional patterns. (C) 1998 Elsevier Science B.V. All rights reserved.