Species Distribution Modeling Reveals Recent Shifts in Suitable Habitat for Six North American Cypripedium spp. (Orchidaceae)

Abstract

Accelerating climate change is expected to cause range shifts of numerous taxa worldwide. While climatic projections and predicted consequences typically focus on the future (2050 or later), a measurable change in climatic conditions has occurred over recent decades. We investigate whether recent climate change has caused measurable shifts in suitable habitat for six North American species in the highly threatened genus Cypripedium (Orchidaceae). We constructed species distribution models using a maximum entropy approach from species occurrence records, 19 bioclimatic variables, land cover data, and soil data for two decadal time intervals (1980–1989 and 2010–2019). Models were compared between time intervals to assess shifts in locality, size, fragmentation, and mean elevation of suitable habitat. For all six congeners, the centroids of suitable habitat shifted between time intervals, although the directionality varied. There was, however, consistency among species within geographic regions. Consistent with our expectations, the optimal habitat for most species shifted to a higher elevation and for western species it shifted northwards. However, the habitat for one northwestern species shifted southwards and the habitat for eastern species converged on the Great Lakes region from different directions. This work illustrates the somewhat idiosyncratic responses of congeneric species to changing climatic conditions and how the geographic region occupied by a species may be more important for predicting shifts in habitat than is the response of a closely related taxon.