Spatiotemporal Structure of Host‐Pathogen Interactions in a Metapopulation

Abstract

The ecological and evolutionary dynamics of species are influenced by spatiotemporal variation in population size. Unfortunately, we are usually limited in our ability to investigate the numerical dynamics of natural populations across large spatial scales and over long periods of time. Here we combine mechanistic and statistical approaches to reconstruct continuous-time infection dynamics of an obligate fungal pathogen on the basis of discrete-time occurrence data. The pathogen, Podosphaera plantaginis, infects its host plant, Plantago lanceolata, in a metapopulation setting where the presence of the pathogen has been recorded annually for 6 years in approximately 4,000 host populations across an area of 50 km x 70 km in Finland. The dynamics are driven by strong seasonality, with a high extinction rate during winter and epidemic expansion in summer for local pathogen populations. We are able to identify with our model the regions in the study area where overwintering has been most successful. These overwintering sites represent foci that initiate local epidemics during the growing season. There is striking heterogeneity at the regional scale in both the overwintering success of the pathogen and the encounter intensity between the host and the pathogen. Such heterogeneity has profound implications for the coevolutionary dynamics of the interaction.

Multiple reciprocal adaptations and rapid genetic change upon experimental coevolution of an animal host and its microbial parasite

“…17). Therefore, the identification of coevolutionary consequences is often difficult and requires complex study designs, such as in long-term analyses across locations and habitats, as performed, among others, for Potamopyrgus snails (5,18) or the ribwort plantain (19).…”

Population Biology of Plant Pathogens

“…If populations are reasonably clearly bounded, it may be possible to capture some of the behaviour of plant pathogens in the system by thinking of the populations as individuals which may be infected with the pathogen or not (Figure 4). Disease dynamics in a host metapopulation may differ from those in a single subpopulation, because the time scale which it is useful to consider is longer, the density-dependence relationships will differ, both infection rates and the lifetime of the pathogen in a subpopulation will differ, and chance plays a larger part (Soubeyrand et al, 2009). Examples of metapopulations studied in detail reveal a remarkable degree of dynamism, with frequent extinction and recolonisation in subpopulations, and correspondingly unpredictable coevolutionary dynamics (Burdon, 1993;Burdon and Thrall, 2013).…”

Patchy patterns due to group dispersal

“…For organisms taken into account in this article, i.e. airborne plant pathogens and plant propagules, the main reasons invoked to explain multiple foci patterns may be (i) spatial heterogeneity in host receptivity or environmental conditions (Kauffman and Jules, 2006;Laine and Hanski, 2006;Soubeyrand et al, 2009), (ii) long distance dispersal (Aylor, 1987;Cannas et al, 2006;Ferrandino, 1993;Filipe and Maule, 2004;Marco et al, 2009;Minogue, 1989), (iii) stratified dispersal (Sapoukhina et al, 2010) and (iv) density-dependence Pacala, 1997, 1999;Dieckmann and Law, 2000). Here, we are interested in another potential reason: group dispersal.…”