Forecasting range shifts of a dioecious plant species under climate change

Global warming has triggered an urgent need for predicting the reorganization of Earth’s biodiversity. Currently, the vast majority of models used to forecast population viability and range shifts in response to climate change ignore the complication of sex structure, and thus the potential for females and males to differ in their sensitivity to climate drivers. We developed demographic models of range limitation, parameterized from geographically distributed common garden experiments, with females and males of a dioecious grass species ( Poa arachnifera ) throughout and beyond its range in the south-central U.S. Female-dominant and two-sex model versions both predict that climate change will alter population viability and will induce a poleward niche shift beyond current northern limits. However, the magnitude of niche shift was underestimated by the female-dominant model, because females have broader temperature tolerance than males and become mate-limited under female-biased sex ratios. Our result illustrate how explicit accounting for both sexes could enhance population viability forecasts and conservation planning for dioecious species in response to climate change.