Molecular systematics and biogeography of the southeast Asian genus Caryota (Palmae)
Hahn, W.J.; Sytsma, K.J.
Systematic Botany 24(4): 558-580
1999
ISSN/ISBN: 0363-6445
DOI: 10.2307/2419643
Accession: 003503139
Restriction site variation of chloroplast DNA was analyzed in nine of the eleven currently recognized species of Caryota. Phylogenetic relationships were estimated and used to examine biogeographic patterns in the genus. Analysis of 49 populations of Caryota and six species from the putative outgroup genera Arenga and Wallichia demonstrated low levels of inter- and intraspecific variation as seen in other groups of palms and long-lived perennials. A total of 796 restriction sites representing 4,752 bp (ca. 4.0%) of the chloroplast genome was detected with 75 sites (9.4% of the total) showing phylogenetically informative variation. Phylogenetic analysis identified three main clades, each with one widespread variable species and one or more geographically restricted species. Hybridization was suggested as a probable explanation for patterns of variation detected in several instances of species sympatry. Biogeographic patterns among the three principal clades are largely congruent with Wallace's 1910 Line or Huxley's Line. The Maxima clade consists of three species restricted to the west of Huxley's Line. The Mitis clade consists of two species found west Huxley's Line and on the island of Sulawesi. The Rumphiana clade includes four species distributed, with one exception, to the east of Huxley's Line and on the border islands of Borneo and Palawan. The economically imporant C. urens, te errant member of the Rumphiana clade, has a distribution disjunct to India and Sri Lanka, possibly a reflection of early human introduction, cultivation, and subsequent natural dispersal into local forests.