Small mammal distributional patterns in Northwestern Argentina

Abstract

ABSTRACT. Quantitative evaluations of species distributional congruence allow evaluating previously proposed biogeographic regionalization and even identify undetected areas of endemism. The geographic scenery of Northwestern Argentina offers ideal conditions for the study of distributional patterns of species since the boundaries of a diverse group of biomes converge in a relatively small region, which also includes a diverse fauna of mammals. In this paper we applied a grid-based explicit method in order to recognize Patterns of Distributional Congruence (PDCs) and Areas of Endemism (AEs), and the species (native but non-endemic and endemic, respectively) that determine them. Also, we relate these distributional patterns to traditional biogeographic divisions of the study region and with a very recent phytogeographic study and we reconsider what previously rejected as 'spurious' areas. Finally, we assessed the generality of the patterns found. The analysis resulted in 165 consensus areas, characterized by seven species of marsupials, 28 species of bats, and 63 species of rodents, which represents a large percentage of the total species (10, 41, and 73, respectively). Twenty-five percent of the species that characterize consensus areas are endemic to the study region and define six AEs in strict sense while 12 PDCs are mainly defined by widely distributed species. While detailed quantitative analyses of plant species distribution data made by other authors does not result in units that correspond to Cabrera's phytogeographic divisions at this spatial scale, analyses of animal species distribution data does. We were able to identify previously unknown meaningful faunal patterns and more accurately define those already identified. We identify PDCs and AEs that conform Eastern Andean Slopes Patterns, Western High Andes Patterns, and Merged Eastern and Western Andean Slopes Patterns, some of which are re-interpreted at the light of known patterns of the endemic vascular flora. Endemism do not declines towards the south, but do declines towards the west of the study region. Peaks of endemism are found in the eastern Andean slopes in Jujuy and Tucumán/ Catamarca, and in the western Andean biomes in Tucumán/Catamarca. The principal habitat types for endemic small mammal species are the eastern humid Andean slopes. Notwithstanding, arid/semi-arid biomes and humid landscapes are represented by the same number of AEs. Rodent species define 15 of the 18 General Patterns, and only in one they have no participation at all. Clearly, at this spatial scale, non-flying mammals, particularly rodents, are biogeographically more valuable species than flying mammals (bat species).KEYWORDS. Chiroptera, Didelphimorphia, distributional congruence, geographical patterns, Rodentia. RESUMEN. Patrones de endemicidad de pequeños mamíferos en el Noroeste de Argentina. Las evaluaciones cuantitativas de congruencia distribucional de las especies permiten comparar regionalizaciones biogeográficas propuestas previamente e incluso identificar ár...

Fleas of mammals and patterns of distributional congruence in northwestern Argentina: A preliminary biogeographic analysis

“…(2015) supported that the Southern sector of the Yungas Forests is a distinctive faunal AE, at least in the case of endemic small mammals. Sandoval et al. (2015) suggested that the main habitat types for endemic small mammal species are not the western or eastern arid or semi-arid biomes, but rather the eastern humid Andean slopes and the results of our study partially agrees with that, because the endemic species of flea are mainly distributed in areas of Yungas Forests but the Monte Desert of Mountains and Isolated Valleys would also be harboring endemic species.…”

“…The pattern of distributional congruence 4 (Monte and Yungas Forests) was also found by Sandoval et al. (2015) , but as an area of endemism in strict sense , named South-eastern Andean Slopes merged with Southwestern Andean Biomes I ( SE-SW ) with Eligmodontia moreni (Thomas, 1896) as an endemic species, whose association with the flea species H .…”

“…All patterns show strong tendency of the Yungas Forests as a possible endemism area. Sandoval and Ferro (2014) identified the entire latitudinal extension of the Yungas Forest as a discrete biogeographical unit in the NWA geographical context, likewise Sandoval et al. (2015) supported that the Southern sector of the Yungas Forests is a distinctive faunal AE, at least in the case of endemic small mammals.…”

“… Morrone and Gutiérrez (2005) proposed that although the comparison of biogeographical patterns exhibited by coevolving taxa is not usually addressed, based on their relationship, similar distributional patterns of host and parasite taxa should be expected. In the case of mammals, main hosts of fleas have more defined biogeographic patterns, because there is more information about their geographical distribution compared to that of parasites ( Sandoval and Ferro, 2014 ; Sandoval et al., 2015 ). Traub (1980) considered that geographical distribution of some flea species is probably related to the plate tectonics and subsequent dispersal and redistribution of the host taxa.…”

“… Sandoval et al. (2015) identified the High Andean and Puna as discrete biogeographic units in the geographic context of NWA and proposed these areas as part of larger AEs extending southward in Argentina and northward into Bolivia.…”