Gerbillus cheesmani, Thomas, 1919

Gbif. Org, Occdownload, 2022, Biogeography of rodents in Iran: species richness, elevational distribution and their environmental correlates, Mammalia (Warsaw, Poland) 86 (4), pp. 309-320 : 312

55 GerbillUs cheesmani

2.3 Richness pattern

We mapped 76 rodent species of Iran following Kafash et al. (2020). Specifically, a convex hull polygon was created in the R software (R Core Team R 2017) around all the observations separately for each species within a particular terrestrial biome. We used five terrestrial biomes as defined by the World Wildlife Fund (WWF); Temperate Broadleaf and Mixed Forests, Temperate Grasslands, Savannahs and Shrublands, Temperate Conifer Forests, Montane Grasslands, Shrublands, Deserts and Xeric Shrublands ( Olson et al. 2001). Range maps created that way were overlaid to produce rodent richness maps in the raster package ( Hijmans 2015). To identify environmental determinants of rodent richness we selected four sets of variables: (i) capturing current climate ( Fick and Hijmans 2017), (ii) past climate (Quaternary climate fluctuations) ( Hijmans et al. 2005), (iii) topography ( Jarvis et al. 2008) and (iv) vegetation ( Pettorelli et al. 2011). Earlier studies showed that these variables are important in shaping biodiversity distribution patterns ( Araújo et al. 2008; Field et al. 2009; Finarelli and Badgley 2010; McCain and Grytnes 2010; Mohammadi et al. 2019). Topographic diversity was defined as the standard deviation of elevations per 1 km 2 grid cells with 90 m resolution (the Shuttle Radar Topography Mission (SRTM) elevation model). The Quaternary climate fluctuations were estimated as changes in climate between the Last Glacial Maximum [LGM] and today ( Sandel et al. 2011). Climate change (temperature/precipitation) velocity is a measurement for long-time climate variability and it shows the direction and rate at which organisms must have moved to maintain a given climate under climate change. This factor was shown to be an important driver of biodiversity distribution in different parts of the world including Iran ( Kafash et al. 2020). LGM data (CCSM4) were downloaded from WorldClim (www.worldclim. org). For the current climate, we used the annual mean temperature and annual precipitation which are freely accessible from WorldClim ( Fick and Hijmans 2017).