Mountain Pine Beetle population dynamics are rightly described in terms of epidemiological stages, i.e., endemic populations, changing to incipient and leading to epidemics (Safranyik, 2004). A clear parallel with human viral or bacterial diseases is obvious. In the case of human diseases, considerable effort is made to understand the population structure of the disease vectors. These studies, conducted by examining the genetic differences among disease outbreaks, reveal valuable information about the spread of the disease. The current worries about avian flu are a case in point. New outbreaks are quickly genotyped to determine the strain responsible and how it has spread from previous outbreaks. This information is critical for effective disease control. In the case of MPB there is a complete lack of information on the genetic relationship of the current outbreaks in different parts of BC and Alberta. This project will provide information that will lead to insights into the historic relationships of current outbreaks and allow hypotheses of MPB dispersal to be tested. There is considerable debate as to the origins of insect outbreaks. There is a perception that the current MPB outbreak spread from Tweedsmuir Provincial Park. Also, the Alberta Forest Service has suggested that outbreaks in Alberta have resulted from dispersal of beetles from infestations in BC. Bark beetles disperse actively over relatively short distances by flight and are also assumed to disperse passively over longer distances (Nilssen 1984, Carroll and Safranyik 2004). However, MPB are endemic to many regions of BC, and ongoing studies on MPB population dynamics indicate that a switch from endemic to incipient outbreaks occurs locally within stands containing suppressed trees (Allan Carroll, pers. comm.). Furthermore, synthesis of outbreak maps by Steve Taylor (www.for.gov.bc.ca/hfp/forsite/overview/mpb_history.htm) indicates that outbreaks occur simultaneously in geographically separate areas. Tracing insect movement has been done by mark-release-capture methods, which are limited to small geographic distances and short time scales (McLean 1980, Safranyik et al. 1992, Salom and McLean 1990, Thoeny et al. 1992) Recent advances in molecular biology have provided unparalleled opportunities for phylogeographic (correlation of genetics with geographic distribution) studies. Genetic analysis of a given population provides a natural marker by which that population can be identified. Relatedness among individuals, and gene flow (and consequently dispersal) between populations can be estimated through the use of microsatellite DNA markers. Microsatellite techniques have been used successfully in numerous species of insects, including bark beetles (Kerdelhue et al. 2003, Hoy 2004). Microsatellite analysis of MPB populations will be conducted in collaboration with a research group at the USDA Forest Service (Barbara Bentz) and the University of Utah (Mike Pfrender and Karen Mock), Logan, UT, that is currently developing microsatellites for the MPB. We will collect MPBs for analysis from a range of geographic locations throughout British Columbia and Alberta. Regions will include the current epidemic outbreak in the Central Plateau, areas of infestation predating the current outbreak, and newly detected populations in Northeastern BC and along the Western slope of the Rockies in Alberta. Beetles will be stored and analyzed at UNBC and genetic data will be freely exchanged with the US group who is conducting a broader and less geographically detailed survey of US bark beetle microsatellite variation. Thus, the fine scale analysis of BC and Alberta, yielding detailed information on the relationship of MPB populations and insight into current and historic beetle dispersal, will be placed into the context of the genetic variation found in MPBs throughout their entire range.
Murray, Brent W.. 2007. Studying mountain pine beetle dispersal patterns through analysis of genetic markers: investigation of population structure and examining current dispersal assumptions. Forest Investment Account (FIA) - Forest Science Program. Forest Investment Account Report. FIA2007MR437
Topic: FLNRORD Research Program
Keywords: Forest, Investment, Account, (FIA), Dendroctonus, Ponderosae, British, Columbia
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