Integrating intraspecific variation in species distribution models by quantifying niche differentiation

Abstract

Abstract Intraspecific variation provides insight into heterogeneous demography and adaptive history across distribution ranges of organisms. Most species distribution models assume that species respond to the environment as a single undifferentiated entity across their entire distribution. However, populations occupying different niches might differ in their ability to cope with climate change. Here, we assessed potential climatic niche differentiation at the species and subspecies levels and identified the palaeoclimatic range of three cold-adapted, low-dispersal beetle species: Carabus irregularis, Platycerus albisomni and Platycerus takakuwai. Our results showed that: (1) MaxEnt models incorporating information derived from intraspecific variation outperformed the species-level models; (2) tests of niche similarity revealed niche conservatism in most subspecies, except for two subspecies of C. irregularis, C. i. irregularis and C. i. bucephalus; and (3) historical predictions suggested substantial shifts within species ranges, with multiple glacial refugia during the Last Glacial Maximum. In conclusion, we recommend closer examination of intraspecific variation when predicting species distributions, in order to obtain more accurate generalizations regarding range shifts under climate change.