Genetic variation within the endangered species Aldrovanda vesiculosa (Droseraceae) as revealed by RAPD analysis

Abstract

Aldrovanda vesiculosa L. (Droseraceae) is an endangered aquatic carnivorous plant species inhabiting standing dystrophic waters across Europe, Asia, Australia, and Africa. Despite its widespread occurrence, its population is patchily distributed. Proliferation in these mostly isolated habitats is largely clonal by shoot branching. We assessed the level of variation of random amplified polymorphic DNAs (RAPDs) in a collection of plants from Europe, Asia, and Australia to study the distribution of genetic variation. The low level of genetic variation found in a previous allozyme study was confirmed in that only 14% of 151 RAPD primers gave polymorphic banding patterns. The proportion of polymorphic bands over all primers was 37% with a mean Jaccard distance of 0.62. Cluster analysis and ordination analysis identified three clusters of closely related plants: an Australian and Japanese accession, a Ukrainian, Russian, and Rumanian accession, and a third accession from Poland and Germany. Although the plants from Germany and NW Australia did not differ from other members of the same RAPD cluster on the basis of morphological or physiological characteristics, these plants were clearly of recombinant origin based on the results of compatibility tests. Remaining accessions possessed RAPD patterns consistent with predominantly asexual mode of reproduction. By focussing on the modes of reproduction in combination with physiological and morphological features, the RAPD analyses can be used for restoration strategies of endangered plant species.