Biogeography and systematics ofCarexsubgenusUncinia(Cyperaceae): A unique radiation for the genusCarexin the Southern Hemisphere

Abstract

AbstractCarexsubg.Uncinia(Cyperaceae) constitutes one of six currently recognizedCarexsubgenera. This subgenus is mainly distributed on the American continent and in the Pacific region, and it is the only subgenus almost entirely absent from the Old World and primarily diversified in the Southern Hemisphere. It includes some of the fewCarexspecies with clear epizoochoric traits: the representatives ofC. sect.Unciniapossess utricles with an exserted and hooked rachilla that allows the diaspores to attach to feather or hair. We performed phylogenetic (ITS, ETS‐1f,matK), biogeographic, and ancestral state reconstruction analyses to elucidate the systematic structure, origin and dispersal routes, and major morphological evolutionary patterns of the different lineages within the subgenus. Our phylogenetic reconstructions revealed that the subgenus comprises seven different clades that mostly match previously recognized sections. One of the clades, however, represents a new section described herein asC. sect.Wheelerianae. Unispicate lineages evolved repeatedly from ancestors bearing multispicate inflorescences, while the presence of a rachilla, often pictured as a plesiomorphy inCarex, seems to have developed four independent times in the evolution ofC. subg.Uncinia. The origin of the subgenus dates back to the beginning of the Miocene, probably in North America from where it colonized the Southern Hemisphere. It first dispersed to South America during the Early Miocene. Later, in the Middle Miocene, representatives ofC. sect.Unciniawould reach the Pacific Southwest region (New Zealand, Australasia) from South America in at least two independent dispersal events. The vast majority of the biogeographic events seem to be explained by long‐distance dispersal. The remarkable dispersal ability ofC. sect.Unciniaenabled by the hooked rachilla has allowed it to reach remote archipelagos in the Pacific and Subantarctic regions, probably bird‐mediated.