Abstract
Abstract Ecoregions and areas of endemism are central concepts in biogeography. Based on collection records and the Endemic Analyses implemented with NDM/VNDM method we analyzed fish areas of endemism in the junction of three freshwater ecoregions related to the Rio de la Plata estuary (Lower Parana, Lower Uruguay, Laguna dos Patos) in Southern Neotropical region. Using two grid cell sizes, results obtained showed the same general patterns. Areas of endemism recovered were mainly associated either to Lower Uruguay or to Laguna dos Patos. In both ecoregions nested areas of endemism were identified within larger patterns of endemism. Noteworthy, one area recovered occurred across Lower Uruguay and Laguna dos Patos limits. Our results also suggest a revision of the Lower Uruguay and Lower Parana ecoregion limits, and highlight the relevance of the Rio de la Plata estuary as a barrier and corridor for freshwater fishes in the area.
Highlights
Distribution of organisms is the result of their ecological and evolutionary history, acting complementarily to generate biogeographic patterns (Wiens, Donoghue, 2004)
Areas of endemism occur in a nested pattern (Morrone, 2008), where smaller areas are included in larger ones, which emphasize their importance in conservation policies, since large areas are the focus of international agencies while smaller ones have to or should be the focus of conservation policies at the national levels
Analyses with 59 x 59 km grid cell size resulted in 40 preliminary Areas of Endemism that after applying a tight consensus of 50 % (Aagesen et al, 2013) were reduced to 22 Consensus Areas (CA, Tab. 1; Fig. S3) whose Endemicity Index (EI) values ranged between 2.3 and 11.8
Summary
Distribution of organisms is the result of their ecological and evolutionary history, acting complementarily to generate biogeographic patterns (Wiens, Donoghue, 2004). Areas of endemism are defined based on the congruent distribution of at least two taxa that do not occur anywhere else (Platnick, 1991; Linder, 2001), which are presumed to have originated by the same historical and/ or ecological factors (Morrone, Crisci, 1995). This concept leads to consider areas of endemism as biologically relevant from the conservation point of view (Moritz, 2002; Richardson, Whittaker, 2010). Ecoregions are spatial units that contain within and compose an area of endemism per se
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