Molecular systematics and biogeography of the Southeast Asian genus Caryota (Palmae)

Restriction site variation of chloroplast DNA was analyzed in nine of the e leven currently recognized species of Caryota. Phylogenetic relationships w ere estimated and used to examine biogeographic patterns in the genus. Anal ysis of 49 populations of Caryota and six species from the putative outgrou p genera Arenga and Wallichia demonstrated low levels of inter- and intrasp ecific variation as seen in other groups of palms and long-lived perennials . A total of 796 restriction sites representing 4,752 by (ca. 4.0%) of the chloroplast genome was detected with 75 sites (9.4% of the total) showing p hylogenetically informative variation Phylogenetic analysis identified thre e main clades, each with one widespread variable species and one or more ge ographically restricted species. Hybridization was suggested as a probable explanation for patterns of variation detected in several instances of spec ies sympatry. Biogeographic patterns among the three principal clades are l argely congruent with Wallace's 1910 Line or Huxley's Line. The Maxima clad e consists of three species restricted to the west of Huxley's Line. The Mi tis clade consists of two species found west Huxley's Line and on the islan d of Sulawesi. The Rumphiana clade includes four species distributed, with one exception, to the east of Huxley's Line and on the herder islands of Bo rneo and Palawan. The economically important C. urens, the errant member of the Rumphiana clade, has a distribution disjunct to India and Sri Lanka, p ossibly a reflection of early human introduction, cultivation, and subseque nt natural dispersal into local forests.