A microsatellite analysis of the western Canadian mountain pine beetle (Dendroctonus ponderosae) epidemic: phylogeography and long distance dispersal patterns

The mountain pine beetle (MPB) is an eruptive insect that is currently causing an outbreak of record size in Western Canada. A lack of long distance MPB dispersal data has limited our understanding of and ability to manage MPB epidemics. My goal was to determine the MPBs Western Canadian population structure, upon which dispersal patterns may be superimposed. I analyzed MPBs from 35 infested lodgepole pine stands at six microsatellite loci. The MPB exhibited strong and significant Western Canadian population structure. This population structure was incongruent with the structure of its primary symbiont, O. clavigerum, but congruent with the structure of its primary host, P. contorta. Novel fungal selection pressures have probably caused the discrepancy in beetle/fungus phylogeography. A result of Western Canadian MPB population structure alternately contrasts and supports population structure previously reported for Scolytids, including MPBs. The partitioning of MPB population structure into a Northern and Southern group is most likely the result of postglacial recolonization and differences in MPB population dynamics. Primarily using my genetic data, I inferred the historical movement patterns of the MPB in Western Canada. I found no evidence that the epidemic spread from an epicenter in Tweedsmuir Provincial Park. My data support multiple sources for the current epidemic I suggest that regional population expansions have caused the rapid escalation in the severity of the current epidemic. MPB movement patterns and atmospheric wind data were concordant winds in Western Canada are predominantly westerly or southwesterly, which was the predominant direction of inferred movements among MPB populations. In contrast, current MPB population structure best fits a 30-year climatic suitability distribution for a historical (1921-1950) as opposed to the most current (1971-2000) period. The population genetics of long distance MPB dispersal, an evolutionary theory for MPB population dynamics, and MPB '~range expans