Confronting species distribution model predictions with species functional traits

Species distribution models are valuable tools in studies of biogeography, ecol-ogy, and climate change and have been used to inform conservation andecosystem management. However, species distribution models typically incorpo-rate only climatic variables and species presence data. Model development orvalidation rarely considers functional components of species traits or othertypes of biological data. We implemented a species distribution model (Max-ent) to predict global climate habitat suitability for Grass Carp (Ctenopharyn-godon idella). We then tested the relationship between the degree of climatehabitat suitability predicted by Maxent and the individual growth rates of bothwild (N = 17) and stocked (N = 51) Grass Carp populations using correlationanalysis. The Grass Carp Maxent model accurately reflected the global occur-rence data (AUC = 0.904). Observations of Grass Carp growth rate covered sixcontinents and ranged from 0.19 to 20.1 g day1. Species distribution modelpredictions were correlated (r=0.5, 95% CI (0.03, 0.79)) with observed growthrates for wild Grass Carp populations but were not correlated (r=0.26, 95%CI (0.5, 0.012)) with stocked populations. Further, a review of the literatureindicates that the few studies for other species that have previously assessed therelationship between the degree of predicted climate habitat suitability and spe-cies functional traits have also discovered significant relationships. Thus, speciesdistribution models may provide inferences beyond just where a species mayoccur, providing a useful tool to understand the linkage between species distri-butions and underlying biological mechanisms.