Checking bioclimatic variables that combine temperature and precipitation data before their use in species distribution models

The 19 BIOCLIM variables available from the WorldClim databases have become most widely used set of climatic for creating species distribution models (SDMs) and ecological niche (ENMs). Nevertheless, in recent years, there has been an increasing trend to exclude four these SDM/ENM analyses. values concerned are interactive as they combine both temperature precipitation assessments. Their exclusion was justified initially due discontinuities their interpolated surfaces observed a study using data version 1 WorldClim. were thought be artefacts measures used, such sudden changes unlikely biologically meaningful. A freely biodiversity database open access geographic information system here check versions 2 Over world, found change smoothly. Major minor discontinuities, however, noted all specific parts some six continents (excluding Antarctica) covered by databases. Discontinuities related quarterly periods calculate variables. These often equatorial regions where only small across year. Bimodal distributions may also cause problems. It is recommended that quick simple method described should facilitate visual inspection numerical checking possible before If variable area, it not used. Ways which could recalculated when new created suggested reduce discontinuity