E. Leger's research focuses on applied evolutionary questions in the Great basin. E. Espeland studies environmental stress, plant–plant interactions, and their effects on evolutionary processes. K. Merrill conducted the SSR genotyping while an under graduate at Brigham Young University, and is now a Master's student with S. Meyer. S. Meyer's current research is focused on the evolutionary ecology of Bromus tectorum and its coevolutionary relationships with fungal pathogens.
Genetic variation and local adaptation at a cheatgrass (Bromus tectorum) invasion edge in western Nevada
Article first published online: 21 SEP 2009
© 2009 Blackwell Publishing Ltd
Volume 18, Issue 21, pages 4366–4379, November 2009
How to Cite
LEGER, E. A., ESPELAND, E. K., MERRILL, K. R. and MEYER, S. E. (2009), Genetic variation and local adaptation at a cheatgrass (Bromus tectorum) invasion edge in western Nevada. Molecular Ecology, 18: 4366–4379. doi: 10.1111/j.1365-294X.2009.04357.x
- Issue published online: 14 OCT 2009
- Article first published online: 21 SEP 2009
- Received 8 January 2009; revision received 12 May 2009; accepted 25 May 2009
- invasive species;
- local adaptation;
- natural selection;
- range limits;
- secondary invasion;
Cheatgrass (Bromus tectorum) is an invasive weed in western North America found primarily growing at elevations less than 2200 m. We asked whether cheatgrass is capable of becoming adapted to a marginal habitat, by investigating a population at a high elevation invasion edge. We used a combination of methods, including reciprocal field transplants, controlled environment studies and molecular analysis. High levels of SSR gene diversity (0.50 vs. 0.43) and comparable variation in phenotypic traits were observed at both the invasion edge and a low elevation, high-density population. Three heterozygotes were observed in the edge population, which is unusual in this predominantly self-pollinating plant. Plants from high elevations germinated more slowly in a growth chamber and had slower seedling growth rates. Survivorship was low at the edge (13%), compared with the low elevation site (55%), but surviving plants were of similar size and had equivalent reproductive output. Seed size positively affected survival and plant performance in the field and this trait was inherited. Emergence timing affected survival at the low elevation site and germination timing was also inherited. Local adaptation was seen in the low, rather than in the high elevation site, because of differential survival. While there was no evidence for local adaptation to the high elevation site observed in the field, family level and genotype-level differences in traits that affected field performance, high genetic diversity at the invasion edge, and evidence of outcrossing in this highly selfing species indicates that the potential for adaptation to a marginal habitat exists within this population.