Exploration of the Ecological Niche of Chacoan Species in Environmental Space

PINOTTI, JUAN DIEGO; GONZÁLEZ?ITTIG, RAÚL ENRIQUE; FERREIRO, ALEJANDRO MANUEL; CHIAPPERO, MARINA B.

Virtual

Encuentro; I Meeting of Systematics, Biogeography and Evolution, a Joint Effort in the Coronavirtual Era; 2020

The Chaco is the only subtropical dry forest in the planet, it contains high levels of endemism and diversity of species1, 2. The destruction of chacoan habitats has been identified as one of the worst environmental disasters in South America3, 4. Ecological niche models (ENMs) allow relating species presences data with information about the environmental characteristics of these ocurrences5. Several studies had implemented ENMs to infer the potential distribution of chacoan species6, 7, but all of them were focused in the geographic space. Regarding that niches are modelled in environmental space8, the characterization of the environmental niche of chacoan species would bring new information about the biogeography of this region.Based on this, we modelled the niches of four predominantly Chacoan taxa with a minimum ellipsoid model (MVE) in the environmental space. We also calculate niche volumes and overlap between them.Occurrences were obtained from field trips and the Global Biodiversity Information Facility (www.GBIF.org) for four species distributed mainly in Chaco:Bulnesia sarmientoi (Bs), Calomys callosus (Animalia, Rodentia, cricetidae) (Cc), Leptodactylus bufonius (Animalia, Leptodactylidae)(Lb), Tolypeutes matacus (Animalia, Xenarthra,) (Tm).Records were spatially filtered with a 15 km distance in spThin package in R9. Bioclimatic variables from WorldClim 1.4 at a 2.5 min resolution were used10. Variables mixing temperature and precipitation were excluded. We determined the accessible historical area of the species with an ecoregional criteria. A Principal Component Analysis (PCA) was performed with the cropped variables. The three first components of the PCA were used to build niches in environmental space. MVE Niche models were constructed and plotted using the software NicheAnalyst v.3.011. Niche volume and overlap were obtained using the same software.Our results show two species with broader niches (L. bufonius and T. matacus) and two with narrower ones (B. sarmientoi and C. callosus). Interestingly, the species with broader niches reach lower latitudes in geographical space (Fig. 1).Regarding the niche overlaps, we see that all of them are overlapped. In fact, there is a zone of the environmental space in which the four species overlap.In this first analysis of chacoan species, we include a woody plant (B. sarmientoi) a rodent (C. callosus) an armadillo (T. matacus) and a frog (L. bufonius). We could model their niches in environmental space and calculate some metrics to characterize them. We think that this approach could be useful to test different biogeographical hypothesis or could complement ecological or taxonomic studies of chacoan species.