Androdioecy is Derived from Dioecy in Datiscaceae: Evidence from Restriction Site Mapping of PCR-Amplified Chloroplast DNA Fragments

Abstract

Androdioecy is a rare reproductive system in plants, which has traditionally been viewed as an intermediate step in the formation of dioecy from hermaphroditism. However, in the Datiscaceae, which comprises three dioecious and one androdioecious species, we have proposed that androdioecy rather than dioecy represents the derived condition. To test this hypothesis, the evolutionary history of Datiscaceae was reconstructed by comparative restriction site mapping of PCR-amplified chloroplast DNA fragments and subsequent cladistic and phenetic analyses. Thirtyeight shortest Wagner trees, 32 shortest Dollo trees, majority-rule consensus trees for each parsimony option, and one shortest genetic distance tree were examined. The androdioecious Datisca glomerata was placed in a derived position relative to the dioecious members of this family in all of these trees. This was also the case for all Dollo and Wagner trees that are oneand two-steps longer than the shortest trees, although not necessarily for Wagner and Dollo trees that are three-steps longer. These data not only support our contention that androdioecy is derived from dioecy in Datiscaceae, they also demonstrate the potential of PCR-mediated restriction site mapping comparisons for reducing the time, expense, and quantity of DNA required for comparative chloroplast DNA anal-