Range-wide ecological niche comparisons of parasite, hosts and dispersers in a vector-borne plant parasite system

Aim: To test whether the distribution of the mistletoe Phoradendron californicum is mediated by host distributions (host niche hypothesis, HNH), or by factors such as the mistletoe’s autecology (parasite niche hypothesis, PNH) or that of its vectors (vector niche hypothesis, VNH). Our null hypothesis is that the ecological niche of the mistletoe will not be distinct from that of its hosts or vectors; alternatively, mistletoe infections might appear in hosts only in regions where host distributions overlap suitable conditions for the parasite. Location: Sonoran and Mojave deserts, western North America. Methods: We used ecological niche modelling approaches to summarize suitable environmental conditions for hosts infected and uninfected with mistletoes, as well as for avian dispersers during winter and throughout the year. We compared ecological niches among pairs of species using background similarity tests in relation to the climatic conditions available and accessible to each species....