Biogeographic insights on P acific C oprosma ( R ubiaceae) indicate two colonizations to the H awaiian I slands

Most archipelagos of the P acific O cean, including the H awaiian I slands, are volcanic in origin and were never connected to continental land masses. The derivation of the H awaiian flora is entirely the result of long‐distance dispersal and in situ speciation from various source areas, including the A mericas, A sia and islands of O ceania. To assess the origins of H awaiian C oprosma ( R ubiaceae), one of the largest and most widely distributed genera across the P acific, molecular phylogenetic analyses were performed utilizing sequences from internal and external transcribed spacer regions ( ITS and ETS ) of nuclear ribosomal DNA and the rps16 plastid DNA intron, from which phylogeographic patterns within the genus were assessed. Our analyses suggest two independent colonization events of C oprosma to the H awaiian I slands. Twelve of the 13 H awaiian C oprosma spp. form a monophyletic group and are closely related to species from the M arquesas I slands and one species from the A ustral I slands. C oprosma ernodeoides represents a separate colonization of the H awaiian I slands from an uncertain origin, but is closely associated to C . atropurpurea of N ew Z ealand and C . pumila of T asmania. Similar to the H awaiian I slands, the pattern of multiple independent colonization events to a single Pacific locality was also found for six S outh P acific localities and for A ustralia. Understanding the origins of H awaiian C oprosma adds a new pattern of plant dispersal to our understanding of P acific biogeography, particularly in reference to multiple independent colonizations to single insular localities. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society , 2014, 174 , 412–424.