Patterns of geographic distribution and their implications on the phylogeny of Puya (Bromeliaceae)

Puya (± 185 species) is widespread at altitudes from sea level to 5000 m and has an extensive range of distribution from Costa Rica to Chile.Previous studies of this genus have been almost entirely taxonomic in nature due to the paucity of field collections and field data.Using extensive field and herbarium data, the present work investigates Puya phylogeny based on geographic distributions and cladistic relationships within the genus.Ten gee^'.ioiix.dregions in the Andean Cordilleras and one region on the Chilean coast constitute centers of diversity where species of Puya are concentrated.Allopatric, endemic, or relatively narrow distributions in mountain ranges or valleys .ijxc-vi,i n ■•->: jpi < i. ■. -i ■ jl .|-i, .,ii «i i > i i> |iu < i U .in i ii io i are evident in a number of allied species and have resulted from vicariance and long-distance dispersal.Several lineages appear to have radiated both vertically (especially in the central Andes) and horizontally (in the northern Andes) during the Pliocene and Pleistocene * b> n > lunatic md i itional pulsations were frequent occurrences.A phylogenetic model presented here for Puya describes species divergence from the Guayana Highlands to the northern Andes and via the central Andes to Chile.This model emphasizes that while arid cycles generally favored spcciation, some episodes in conjunction with uplift of tectonic units caused extinction of lineages.