Effect of selection on genetic diversity in native grass species
With the increased emphasis to use native plant materials in range revegetation programs the use of improved native plant materials often becomes a source of controversy. Surrounding this controversy is typically the question – does selection of better performing genotypes reduces the genetic diversity within the selected native grasses? This presentation describes the difference in population structure between self- and cross-pollinated grasses and how that may affect selection within each type.
As a general rule, cross-pollinating grasses have 70% of their genetic variation within a population with 30% between populations. Using AFLP, 27 and 73% of the total variation was between populations and within populations of Snake River wheatgrass (Elymus wawawaiensis J. Carlson & Barkworth), respectively. Similar trends were reported in bluebunch wheatgrass [Pseudoroegneria spicata (Pursh) Á. Löve] at 15 and 67% between and within populations, respectively. Conversely in California bromegrass [Bromus carinatus Hook. & Arn.], which is self-pollinating, 5% of the variation was within populations and 95% between populations, opposite that of cross-pollinating grasses. In general, selection for seedling establishment, traits associated with seed yield, and persistence in bluebunch and Snake River wheatgrass did not reduce the genetic diversity within the selected population when compared to the unselected population. Data suggests that the number of individuals used in the first selection cycle can influence the genetic diversity within the selected populations.