Past, present and future distribution of Bouteloua gracilis, a key species of North American grasslands, changes related to climate change

The emergence of North American grasslands occurred no earlier than the postglacial period. As a key species, Bouteloua gracilis has been widely studied, and authors have suggested a northward migration from Mexico towards the United States. B. gracilis is extremely vulnerable to present global climate change and distribution modeling at different times (Last Glacial Maximum-LGM, mid-Holocene, Present and Future) would be helpful to infer its past distribution and expansion and to predict its responses to future change. Precipitation of the driest month was the most informative variable in the distribution models. Mean temperature of the wettest quarter provided unique information for the future distribution. During the LGM, the most probable distribution of the species was limited to central Mexico and Chihuahua. The largest expansion of the B. gracilis distribution area was projected to be in the mid-Holocene. Climatic variables among the four climatic time periods were not statistically different. Postglacial expansion of B. gracilis from Mexico to the north was supported; since then the distribution area of the species has changed minimally. Future distribution predictions for B. gracilis suggest climate change will not be the sole factor affecting the distribution of the species.