Phylogenetic relationships in Malesian-Pacific Piper (Piperaceae) and their implications for systema
Department of Biology, University of Missouri – St. Louis, 1 University Boulevard, St. Louis, Missouri 63121, U.S.A.; Missouri Botanical Garden, P.O. Box 299, St. Louis, Missouri 63166, U.S.A.; 3 Herbarium Bogoriense, Research Center for Biology, Indonesian Institute of Sciences, Jalan Raya Jakarta-Bogor KM 46, Cibinong 16911, West Java, Indonesia; firstname.lastname@example.org
Comprised of ~2000 spp., Piper is a major clade in the magnoliid angiosperms. Three major groups are recognized in Piper, i.e. the Neotropical, Asian and South Pacific. Unlike Neotropical Piper, relationships in the Paleotropical Piper remain enigmatic. This study evaluates the relationships within Paleotropical Piper by focusing sampling efforts in the Malesian region. This is the center of diversity of the genus in the paleotropics, yet has been barely represented in previous phylogenetic studies. Eleven out of 14 infrageneric groups in Paleotropical Piper and 14% of the species were included in this study and their phylogenetic relationships were inferred based on the nuclear (ITS and g3pdh) and chloroplast (trnL-F) regions. The goals were to test the monophyly of infrageneric groups, to examine how the main characters used to delimit these infrageneric groups have shaped classifications past and present, and to understand the origin of bisexual flowers and the shrubby habit in the predominantly dioecious Asian clade of climbers. The results show that the Asian clade is monophyletic in all phylogenies and the South Pacific clade is monophyletic in nuclear phylogenies. Within the Asian clade, species predominantly distributed west of Wallace’s Line (WWL) form a moderately/strongly supported clade in the ITS phylogeny, embedded within a grade of species from east of Wallace’s Line (EWL). The ITS phylogeny also resolves 12 and 5 clades in the WWL clade and the EWL grade, respectively. G3pdh and trnL-F phylogenies resolve some of the same clades, but some relationships among and within clades are incongruent. Almost no currently recognized infrageneric groups in Asian Piper are monophyletic. Most of the characters previously used to delimit infrageneric groups are homoplasious, including fruit type, bract type, direction of anther dehiscence, and number of anther valves. However, bract and fruit types are still of some value in that many clades in the Asian Piper are characterized by single bract and fruit types. In Paleotropical Piper, bisexual flowers have evolved numerous times in almost every clade, and shrubby habit has evolved at least six times, but is restricted to four clades in the WWL clade. The 17 clades resolved in this study are described along with their potential diagnostic characters.
Key words classification; climber; dioecy; Paleotropical Piper; phylogeny