PARENT SESSION
Organized Oral Session 3: Plant Pathogens in Nature: Rethinking Vegetation Dynamics
Organized by: CM Malmstrom and A Power
Wednesday, August 6. 8:00 AM to 11:30 AM, SITCC Meeting Room 205.

Spatial patterns of disease incidence in plants: metapopulations and beyond.

Alexander, Helen^*,1, Antonovics, Janis², Thrall, Peter ³, ¹ University of Kansas, Lawrence, Kansas² University of Virginia, Charlottesville, Virginia³ CSIRO, Canberra, A.C.T., Australia

ABSTRACT- The majority of host-pathogen studies are focused on small spatial scales, yet plants and pathogens exist in patches, populations, metapopulations, and regional assemblages. At large spatial scales, both abiotic factors and biotic factors (such as host density and isolation of host patches) will affect disease patterns. We will discuss three types of methods for studying disease processes at large spatial scales. First, for some plant hosts, we can define discrete host patches, and disease incidence can be studied between and among patches. Second, for plant hosts with generalist habitats, discrete host patches cannot be easily defined, but large scale processes can be studied by superimposing a grid over favorable plant habitat, and studying plants and their diseases in arbitrary units of space. Third, herbarium collections can provide a surprising source of information on spatial, as well as temporal, patterns of disease incidence. We will illustrate these methods with three host-pathogen systems. For studies of discrete host patches, we will describe studies of Alternaria infection of the beach plant, Cakile maritima, where discrete plant populations exist on beaches that are separated from other beaches by rocky intertidal areas. To illustrate research on diseases of plants with habitat generalists, we will discuss infection of Silene alba by the anther smut pathogen, Microbotryum violaceum, and infection of Helianthus annuus by the rust Puccinia helianthi. Finally, we will illustrate research with herbarium specimens with studies of anther-smut infection of Silene species. For all methods and systems, research on larger spatial scales provides perspectives that are not apparent from small-scale studies.

Key words: disease, metapopulation, spatial