Environmental variation shapes genetic variation in Bouteloua gracilis: Implications for restoration management of natural populations and cultivated varieties in the southwestern United States. Issue 1 (26th December 2018)

• Record Type: Journal Article
• Authors: Tso, Katrina L.; Allan, Gerard J.
• Is Part Of: Ecology and evolution. Volume 9:Issue 1(2019)
• Page Start: 482
• Page End: 499
• Publication Date: 2018-12-26
• Subjects: blue grama -- Bouteloua gracilis -- cultivars -- population genetics -- restoration -- seed source; Ecology -- Periodicals; Evolution -- Periodicals; 577.05
• DOI: 10.1002/ece3.4767
• Languages: English
• ISSNs: 2045-7758

Abstract

Abstract: With the increasing frequency of large‐scale restoration efforts, the need to understand the adaptive genetic structure of natural plant populations and their relation to heavily utilized cultivars is critical. Bouteloua gracilis (blue grama) is a wind‐dispersed, perennial grass consisting of several cytotypes (2 n = 2×–6×) with a widespread distribution in western North America. The species is locally dominant and used regularly in restoration treatments. Using amplified fragment length polymorphism (AFLP) and cpDNA analyses, we assessed the genetic variability and adaptive genetic structure of blue grama within and among 44 sampling sites that are representative of the species' environmental and habitat diversity in the southwestern United States. Five cultivars were also included to investigate genetic diversity and differentiation in natural versus cultivated populations. Three main findings resulted from this study: (a) Ninety‐four polymorphic AFLP markers distinguished two population clusters defined largely by samples on and off the Colorado Plateau; (b) substructure of samples on the Colorado Plateau was indicated by genetic divergence between boundary and interior regions, and was supported by cytotype distribution and cpDNA analysis; and (c) six AFLP markers were identified as "outliers, " consistent with being under selection. These loci were significantly correlated to mean annual temperature, mean annual precipitation, precipitation of driest quarter, and precipitation of wettest quarter in natural populations, but not in cultivated samples. Marker × environment relationships were found to be largely influenced by cytotype and cultivar development. Our results demonstrate that blue grama is genetically variable, and exhibits genetic structure, which is shaped, in part, by environmental variability across the Colorado Plateau. Information from our study can be used to guide the selection of seed source populations for commercial development and long‐term conservation management of B. gracilis, which could include genetic assessments of diversity and the adaptive potential of both natural and cultivated populations for wildland restoration. Abstract : Blue grama is a naturally occurring and widely distributed species that is often cultivated for use in restoration. We found that natural populations differed significantly in their response to environmental variation relative to cultivated varieties, which showed no response. This suggests that the adaptive potential of cultivated varieties may be compromised, making them less suitable for restoration in the wild.