Beyond endemism, expanding conservation efforts: a relictual Pleistocene distribution and first report of the prickly pear cactus, Opuntia bonaerensis, in Brazil and Uruguay

Abstract

21Geographical range is one of the critical features for species conservation assessment. 22 Nevertheless, species distribution is frequently unknown, undervalued or overlooked. During a 23 broad taxonomic and floristic study of the southern South American prickly pear species 24 (Opuntia spp.), new records of a previously endemic Argentinian taxon have been found in 25 Uruguay and Brazil. Molecular phylogenetic inference was carried out to further evaluate the 26 identity of the new records, and ecological niche models were implemented to test how the new 27 records would fit in the previous known distribution of the species. Through molecular and 28 morphological evidence, we confirmed the new records of Opuntia bonaerensis for Brazilian and 29 Uruguayan floras and discussed its phylogenetic relationship and morphologic similarities with 30 closely related species. Our new records uncovered a distributional pattern congruent with the 31 Neotropical Peripampasic Orogenic Arc, which must be further explored to better determine the 32 biogeographic history of the species. Ecological niche models (ENM) revealed that O. 33 bonaerensis had a putative ancient distribution across the grasslands and shrublands in the 34 Pampean region largely congruent with the populations found in Brazil and Uruguay, suggesting 35 relictual Pleistocene populations of the species and the role of glacial/interglacial cycles on the 36 distribution of the species. In a prospective climate change scenario, ENM suggests that the 37 species would in general be more restricted to the southernmost limits of the Pampa region and 38 previous outlying records from Mendoza (Argentina) are a putative future refuge for O. 39 bonaerensis. The importance of these new records for biodiversity and conservation assessment 40 efforts that are ongoing at different scales in Brazil and neighbor areas is highlighted.41 3