|
|
||||||||
Population Biology |
2School of Biological Sciences, Washington State University, Pullman, Washington 99164-4238 USA; 3Department of Biology, Boise State University, 1910 University Drive B, Boise, Idaho 83725 USA
Bromus tectorum, a devastating plant invader in western North America, had entered Pennsylvania by 1790. Although rare, or extirpated, in the east until the 1850s, it was collected with increasing frequency after 1859 from Vermont to Virginia. Using enzyme electrophoresis, we analyzed 38 populations of this grass in the eastern U.S. to determine their genetic variation and structure as well as assess their relatedness to populations in the west. Genetic variation among eastern U.S. populations is low: mean number of alleles per locus (A), percent polymorphic loci per population (%P), and expected heterozygosity (Hexp) are 1.01, 1.05%, and 0.002, respectively. No heterozygotes were detected. The eastern populations are genetically similar: mean genetic identity for all populations was 0.990 with values among population pairs ranged from 0.913 to 1.000. Thirteen populations in eastern and western North America shared Pgm-1a and Pgm-2a, while eight populations shared Mdh-2b and Mdh-3b. Other alleles detected in western North America (Got-4c, Got-4d, and Pgi-2b) were not, however, found in eastern U.S. populations. The invasion of North America by B. tectorum occurred through multiple introductions on both coasts; results from historical and genetic evidence suggest that eastern populations stem from a minimum of two introductions. The 19th century westward spread of B. tectorum from the East appears to be plausible.
Key Words: allozyme variation biotic invasion Bromus tectorum cheatgrass genetic bottleneck multiple introductions Poaceae
This article has been cited by other articles:
![]() |
M. T. Valliant, R. N. Mack, and S. J. Novak Introduction history and population genetics of the invasive grass Bromus tectorum (Poaceae) in Canada Am. J. Botany, July 1, 2007; 94(7): 1156 - 1169. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. J. DeWalt and J. L. Hamrick Genetic variation of introduced Hawaiian and native Costa Rican populations of an invasive tropical shrub, Clidemia hirta (Melastomataceae) Am. J. Botany, August 1, 2004; 91(8): 1155 - 1162. [Abstract] [Full Text] [PDF] |
||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |