Amplified fragment length polymorphisms (AFLP) reveal details of polyploidevolution in Dactylorhiza (Orchidaceae)

The utility of the PCR-based AFLP technique (polymerase chain reactions amp lified fragment length polymorphisms) was explored in elucidating details o f polyploid evolution in the Eurasian orchid genus Dactylorhiza. We emphasi zed Swedish taxa but also included some material from the British Isles and elsewhere in Europe. Three different sets of primers, amplifying different subsets of restriction fragments, independently revealed similar patterns for relationships among the Dactylorhiza samples investigated. The AFLP dat a support the general picture of polyploid evolution in Dactylorhiza, i.e., that allotetraploid derivatives have arisen repeatedly as a result of hybr idization beween the two parental groups D. incarnata s.l. (sensu lato; dip loid marsh orchids) and the D. maculata group (spotted orchids), Within the incarnata s.l. group. morphologically defined varieties were interdigitate d. The D. maculata group consisted of two distinct subgroups, one containin g autotetraploid D. maculata subsp. maculata and the other containing diplo id D. maculata subsp. fuchsii. Allotetraploids showed a high degree of addi tivity for the putative parental genomes, and relationships among them were partly correlated to morphologically based entities. but also to geographi c distribution. Thus, allotetraploid taxa from the British Isles clustered together, rather than with morphologically similar plants from other areas.