Establishing species' environmental requirements to understand how the southernmost species of South American pitvipers (Bothrops, Viperidae) are distributed: A niche‐based modelling approach

Abstract

Three Bothrops species are known to be present along an extensive and generally xeric band of the south‐eastern portion of South America. Yet, the environmental factors responsible for the maintenance of the structure of this community have remained undetermined. To have a better understanding of snakes' geographic range limits in Argentina, we modelled the ecological niche of Bothrops alternatus, B. ammodytoides and B. diporus to identify areas of their occurrence and sympatry. We used snakes presence records and pseudo‐absence data with topographic (altitude and slope), vegetation and 19 bioclimatic variables as predictors. These variables were evaluated for each species, using Multiple Logistic Regression Analysis. The distribution of B. alternatus was correlated with temperature, precipitation and vegetation; that of B. ammodytoides with altitude, slope, precipitation, temperature and vegetation; and that of B. diporus related only to precipitation and temperature variables. Five variables appeared in all three models (i.e. annual precipitation, precipitation seasonality, precipitation of the driest month, mean diurnal temperature range and temperature range), although with different effects in different species. Probable sympatry areas were identified, for B. alternatus – B. ammodytoides in a narrow area, for B. diporus – B. alternatus in a wide area and B. ammodytoides – B. diporus in a small area. While some factors constrain the distribution of the southernmost pitvipers community in South America to spatially non‐overlapping ranges, others facilitate sympatry by allowing spatial coexistence. We found high sympatry between phylogenetically distantly related pitvipers. Niche‐based Geographic Information Systems modelling allowed us to identify the environmental factors correlated with each pitviper range in Argentina and in its contact zones, and to understand species distributional limits.

Understanding the ecological niche to elucidate spatial strategies of the southernmost Tupinambis lizards

“…The topographic variable used was Altitude (ALT), which was also obtained from WorldClim (Hijmans et al, 2005) with a pixel size of 1 km x 1 km. Such composites of NDVI, LST, precipitation and topographic data have been shown to be effective data inputs for large-scale predictions of reptile species distributions (Guisan and Hofer, 2003;Di Cola et al, 2008;Brito et al, 2011;Di Cola and Chiaraviglio, 2011).…”

“…For instance, they have been useful in assessing species niches (Gray et al, 2009;Beaudry et al, 2010;Anadón et al, 2012), determining the environmental factors responsible for the geographical ranges of a species (Di Cola et al, 2008;Di Cola and Chiaraviglio, 2011) and considering questions involving the environmental niches of related taxa (Debandi et al, 2011). Moreover, from an ecological and evolutionary perspective, species distribution models help to elucidate the spatial strategies of species at a regional scale (Luxbacher and Knouft, 2009;Debandi et al, 2011 ;Di Cola and Chiaraviglio, 2011).…”

“…Finally, altitude influences life history traits, such as sexual maturity and egg size in lizards (Rohr, 1997;Iraeta et al, 2008). Species distribution models can assess the role of these environmental factors in determining the presence of each species (Di Cola et al, 2008;Debandi et al, 2011;Di Cola and Chiaraviglio, 2011;Anadón et al, 2012).…”

Species distribution models and empirical test: Comparing predictions with well‐understood geographical distribution of Bothrops alternatus in Argentina

“…SDMs relate species occurrence data with a set of variables selected under the assumption that they could be related to the distribution of the species (Guisan & Zimmermann, ). They are being increasingly used to assess conservation applications and climate change studies, and predict both ecological ranges and the potential of invasive species and explicit predictions about species environmental suitability (Bosso et al., ; Chen, Zhang, Jiang, Nielsen, & He, ; Law et al., ). SDMs are favored by an increased access to public biodiversity (e.g., Biodiversity Information System for Europe, Global Biodiversity Information Facility and Sistema de Información de Biodiversidad) and environmental databases (e.g., Data Service and Information, Global Environmental Database, WorldClim), being also a promising tool to fill knowledge gaps in species distributions (Guillera‐Arroita et al., ; Guisan et al., ).…”

The Role of Landscape in Contact Zones of Sister Species of Lizards

“…Many biotic and abiotic variables might influence species distribution and determine allopatry or simpatry (Di Cola & Chiaraviglio, 2010). Moreover, species patterns are strongly associated with habitat variables at different spatial scales (Hatten & Paradzick, 2003).…”