The Patagonian Steppe Biogeographic province: Andean region or South American transition zone?

ROIG-JUÑENT, SERGIO ALBERTO; GRIOTTI, MARIANA; DOMINGUEZ, M. C.; AGRAIN, FEDERICO ALEJANDRO; CAMPOS-SOLDINI, PAULA; CARRARA, RODOLFO; CHELI, GERMÁN; FERNANDEZ CAMPON, F.; FLORES, GUSTAVO ERNESTO; KATINAS, LILIANA; MUZÓN, J. R. ; NEITA MORENO, JHON CESAR; PESSAQ, PABLO; SAN BLAS, GERMAN; SCHEIBLER, E. E.; CRISCI, J. V.

ZOOLOGICA SCRIPTA

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2018

0300-3256

The Patagonian Steppe Biogeographic province: Andean Region or South American transition zone? A reconsideration of the Andean Region. Zoologica scripta, 00, 000-000.America comprises three biogeographic regions: Nearctic, Neotropical, and Andean. In between them, two transition zones (TZ) have been proposed: Mexican and South American. The biogeographic provinces constituting each of the three regions are characterized by a predominance of biogeographic elements that originated in them, whereas biogeographic provinces belonging to a TZ do not have a predominance of elements pertaining to each of its bordering regions. The Andean Region has three biogeographic provinces, but one of them, the Patagonian Steppe, shows a mixture of different biotic elements which are typical of transition zones. Because of this, we assessed whether the Patagonian Steppe belongs to the Andean Region or whether it forms the southernmost part of the South American TZ. We recompiled phylogenetic information on 177 taxa that inhabit the Patagonian Steppe and established their origin and which biogeographic element they belong to, based on their current distribution as well on the distribution of the sister group of each genus. We set the criterion that an area can be considered a part of a region when the proportion of shared biogeographic elements is at least as high as 70%. We found that the Patagonian Steppe presents a similar proportion of genera of both Andean and Neotropical origin, and a third group including a very small proportion of genera of Pangeic origin. Therefore, we propose that this province should be included in the South American Transition Zone rather than in the Andean Region. Moreover, inclusion of the Patagonian steppe as part of this TZ will make it the largest TZ of America, encompassing most of the arid lands of South America.