Shannon Meadley Dunphy

Student Speaker | Étudiant.e
All species have limited geographic distributions, constrained by their abiotic and biotic environments. Biotic interactions can strongly affect species ranges, yet their role is tricky to pin down. This is especially true for species that rely strongly on others, such as parasites. While parasites’ maximum geographic ranges are set by those of their hosts, many use diverse host species and the extent to which their realized ranges are directly limited by host availability vs their intrinsic climate niche is unclear. To quantify how often host distributions dictate parasite distribution I compiled a dataset of North American mistletoes (123spp), and hosts trees (250spp) range maps. I quantified the match of mistletoe and host distributions at their range edge and the proportion of composite host range occupied by the mistletoe. I show that host range is actually a poor predictor of parasite range, as most mistletoes underfill their potential host niche. I explore the consequences of host breath size on mistletoe distribution. My data synthesis provides a compressive analysis of >50 mistletoe ranges, many of which are hugely problematic for the forestry industry. Understanding the ecological factors that determine the size, shape, and location of species ranges is a foundational goal of ecology, and increasingly important for predictions and planning in conservation and industry.