Disease dynamics, host specificity and pathogen persistence in isolated host populations

Abstract

Carlsson-Granér, U. 2006. Disease dynamics, host specificity and pathogen persistence in isolated host populations. Á/ Oikos 112: 174 Á/184.In situations where populations of related host species grow sympatrically but isolated from other populations of either host, cross-species disease transmission can have large influences on disease dynamic and patterns of pathogen persistence. This study examined host Á/pathogen dynamics and the degree of host-specificity in the anthersmut fungus Microbotryum violaceum at a site where two of its host species, Lychnis alpina and Silene rupestris, grew in adjacent patches which were located at large distances from the nearest intra-specific host and pathogen populations. In a fieldstudy carried out over a four-year period in the sympatric populations, the two host species exhibited broadly parallel patterns of mortality and recruitment across years, although higher rates of mortality and infection, and larger fluctuations in numbers of plants, were seen in the S. rupestris population. However, when the frequency of disease in the populations was taken into account, disease transmission rates were relatively similar in the two hosts. In a reciprocal cross-inoculation experiment, there were no differences in infectivity between the two fungal populations on progeny of the two hosts from the sympatric populations indicating that cross-species disease transmission is possible. Patterns of infectivity on plants from the sympatric populations and allopatric populations of each host indicated the occurrence of a host shift in M. violaceum from L. alpina onto S. rupestris at the sympatric site. Results from a population model, parameterised with the demographic data from the two hosts, demonstrated that some cross-species disease transmission could increase the frequency of disease and lower the threshold level of pathogen persistence in populations. The population model also suggests that high levels of juvenile infection, as observed in both hosts, may increase the probability of pathogen persistence in local populations, especially in the more short-lived S. rupestris. U.

Distribution of race-specific resistance against Bremia lactucae in natural populations of Lactuca serriola

“…Some additional population studies have been published for other wild plant pathosystems, e.g. Filipendula ulmaria-Triphragmium ulmariae (Ericson et al 2002;Smith et al 2003); Plantago lanceolata-Podosphaera plantaginis (Laine 2004(Laine , 2005Laine and Hanski 2006;Laine 2007); Senecio vulgaris-Erysiphe fischeri (Bevan et al 1993a, b, c); Silene spp.-Ustilago violacea (Microbotryum violaceum) (Thrall and Antonovics 1995;Alexander et al 1996;Delmotte et al 1999;CarlssonGranér and Thrall 2002;Carlsson-Granér 2006); and Valeriana salina-Uromyces valerianae (Ericson et al 1999). However, there is a large knowledge gap regarding interactions between weed host plants and oomycetes (Holub 2008;Lebeda et al 2008), despite the fact that oomycete pathogens represent an important group of species which are common in nature and have a world-wide distribution (Lebeda and Schwinn 1994).…”

Spatiotemporal Dynamics of the Epidemic Transmission in a Predator-Prey System

“…This is very true for social species due to their high contact rate. Hitherto, studies have been carried out with the aim of controlling the disease effectively and developing suitable vaccination policies (Chattopadhyay et al, 2002;Grassly and Fraser, 2006;Carlsson-Grańer, 2006). However, infectious diseases in wild species have largely been neglected (but see Pal et al, 2006).…”

Disease in Natural Plant Populations, Communities, and Ecosystems: Insights into Ecological and Evolutionary Processes

“…Over an archipelago of islands, anther-smut disease levels were often dependent on host population age, size, and density (37), with loss of disease in some small populations. Cross-species disease transmission can also be important in the local persistence of the disease at some sites (35).…”