Biogeography of parasitism in freshwater fish: spatial patterns in hot spots of infection

along environmental gradients, dispersal constraints imposed by topography, and intrinsic species differences in dispersal abilities (Soininen et al. 2007). The limited evidence available to date suggests that environmental gradients are more important drivers of the distance decay in parasite community composition than spatial distance per se (Krasnov et al. 2005, Vinarski et al. 2007, Thieltges et al. 2010, Poulin et al. 2011). Whereas much effort has gone toward elucidating the determinants of the spatial occurrence of parasite species, a single study has applied the distance decay model to intraspecific variation in parasite abundance across a geographical scale (Poulin et al. 2011). Abundance and occurrence are not independent: one of the first documented macroecological patterns is that species occurring in many localities on a regional scale also tend to be abundant locally (Brown 1984). Nevertheless, abundance of given parasite species can vary by more than one order of magnitude across their range (Poulin 2006). Thus, uncovering spatial patterns of parasite population parameters is crucial for epidemiology, veterinary medicine and wildlife management. Local parasite abundance is influenced by the interaction of both Ecography 38: 301–310, 2015 doi: 10.1111/ecog.01020 © 2014 The Authors. Ecography © 2014 Nordic Society Oikos Subject Editor: Jennifer Martiny. Accepted 27 June 2014