Conservation genetics of an endangered rainforest tree (Fontainea oraria-Euphorbiaceae) and implications for closely related species

Abstract

Four new eastern Australian Fontainea species have been recently described and all have a limited distribution. F. oraria is the rarest, being restricted to 10 adult individuals within a single site in regrowth littoral rainforest. In order to develop adequate management strategies, this study was aimed at surveying the genetic variability remaining within the species by using RAPD analysis. To assist with the correct interpretation of the results, a matching study was conducted on four populations of the closely related F. australis. Similar amounts of within-population genetic diversity were recorded for both species. The RAPD-based study suggested that adult plants are contributing unevenly to successive generations. RAPD analysis also recognised a close evolutionary relationship between F. oraria and F. australis. Sequencing of cpDNA (trnL-F) and nrDNA (ITS2) regions, confirmed recent divergence and possibly some historical reticulation between these two species and two other members of the genus. Of particular interest was the recognition that one of the F. australis populations (Limpinwood) represented a novel genotypic combination in need of conservation attention. The implications of the RAPD and sequencing results are discussed in reference to their influence upon the development of adequate conservation strategies for all important conservation units.