PARENT SESSION
Contributed Oral Session 11: Invasive Species: Arid Lands
Monday, August 8, 8:00 AM - 11:30 AM, Meeting Room 520 A, Level 5, Palais des congrès de Montréal
Genetic variation in Bromus tectorum: seperate introductions into Eastern and Western Canada.
Valliant, Morgan*,1, Mack, Richard1, Novak, Stephen 2, 1 Washington State University, Pullman, Wa2 Boise State University, Boise, Id
ABSTRACT- The invasive grass Bromus tectorum (cheatgrass) occurs in Canada primarily south of 50° N latitude in a transcontinental range that is interrupted by extensive coniferous forests in western Ontario. The grass's genetic structure in 52 populations in the two major portions of its Canadian range (British Columbia to Manitoba; eastern Ontario to Nova Scotia) was assessed with enzyme electrophoresis and compared with results from populations in the U.S. and its native Eurasian range. Eastern and western Canadian populations differ in their origin, character and proportions of genetic variation. Within-population genetic diversity of cheatgrass in eastern Canada is higher than that found in the eastern U.S. where genetic diversity is exceptionally low. Heterozygotes, which have been rarely detected in North American cheatgrass populations, occur in two populations in Ontario and likely represent novel genotypes. Among-population genetic variation in the eastern range (Gst = 0.481) is slightly higher than that of western populations (Gst = 0.329). Eastern and western Canadian populations exhibit substantially lower among-population variation than those from Eurasia (Gst = 0.754). The variants Pgm-1a and Pgm-2a, which are uncommon across the grass's native Eurasian range, are prevalent in populations from Ontario and British Columbia. In contrast, the variant Got-4c, which in the native range is found only in two populations in Central Europe, is found throughout western Canada. The occurrence of the Pgm-1a and Pgm-2a variants near seaports in both Ontario and British Columbia suggests the grass entered on each coast in the late 19th century through separate introduction events, rather than dispersing along a single east-west Canadian corridor, such as a transcontinental railroad right-of-way.
Key words: Bromus tectorum, Canada, invader, immigration