RAPD marker diversity within and divergence among species of Dendroseris (Asteraceae : Lactuceae)

Random Amplified Polymorphic DNA (RAPD) markers were used to measure geneti c diversity within and divergence among species of Dendroseris (Asteraceae: Lactuceae), a genus endemic to the Juan Fernandez Islands, Chile. Results were compared to previous studies employing allozymes. For five of the spec ies. RAPD banding patterns distinguished all individuals examined, and diff erent mutilocus genotypes were found even in species exhibiting no allozyme diversity. RAPD band diversities ranged from 0.003 to 0.022 within species ; >90% of total diversity was among species and <10% within them. Relative levels of allozyme and RAPD diversity were similar for some species, partic ularly those with highest and lowest diversities, but overall there was no significant correlation. Relationships inferred from a neighbor-joining tre e generated from RAPD bands were similar to results obtained from morpholog y, chloroplast DNA (cpDNA) restriction site mutations, and sequences from t he internal transcribed spacer regions of nuclear ribosomal DNA (ITS), but somewhat better resolution was achieved. Relationships shown by allozymes d iffered from trees based on other data; this ostensibly is a result of the sharing of ancestral alleles and the absence of alleles generated subsequen t to speciation. Dendroseris represents an example where RAPD markers, beca use of their greater variability, provide a useful alternative to allozymes for assessing diversity in rare species endemic to oceanic islands and for resolving relationships among the species.