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

ROIG-JUÑENT, SERGIO; M. CECILIA DOMÍNGUEZ; MARIANA GRIOTTI; FEDERICO A. AGRAIN; PAULA CAMPOS-SODINI; CARRARA, RODOLFO; GERMÁN H. CHELI; FERNÁNDEZ CAMPÓN, FLORENCIA; FLORES, GUSTAVO ERNESTO; KATINAS, L.; MUZÓN, JAVIER; NEITA MORENO, JHON CÉSAR; PESSAQ, P.; SAN BLAS, GERMÁN; SCHEIBLER, ERICA; CRISCI, J.V.

ZOOLOGICA SCRIPTA

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2018

0300-3256

America comprises three biogeographic regions:Nearctic, Neotropical, and Andean. In between them, two transitionzones (TZ) have been proposed: Mexican and South American. Thebiogeographic provinces constituting each of the three regions arecharacterized by a predominance of biogeographic elements thatoriginated in them, whereas biogeographic provinces belonging to a TZdo not have a predominance of elements pertaining to each of itsbordering regions. The Andean Region has three biogeographicprovinces, but one of them, the Patagonian Steppe, shows a mixture ofdifferent biotic elements which are typical of transition zones.Because of this, we assessed whether the Patagonian Steppe belongs tothe Andean Region or whether it forms the southernmost part of theSouth American TZ. We recompiled phylogenetic information on 177 taxathat inhabit the Patagonian Steppe and established their origin andwhich biogeographic element they belong to, based on their currentdistribution as well on the distribution of the sister group of eachgenus. We set the criterion that an area can be considered a part ofa region when the proportion of shared biogeographic elements is atleast as high as 70%. We found that the Patagonian Steppe presents asimilar proportion of genera of both Andean and Neotropical origin,and a third group including a very small proportion of genera ofPangeic origin. Therefore, we propose that this province should beincluded in the South American Transition Zone and rather than in theAndean Region. Moreover, inclusion of the Patagonian steppe as partof this TZ will make it the largest TZ of America, encompassing mostof the arid lands of South America.