Conservation implications of the introduction history of meadow fescue (Festuca pratensis Huds.) to the Driftless Area of the Upper Mississippi Valley, USA

Background: Meadow fescue (Festuca pratensis) is an important cold climate pasture grass that faces pressures from climate and land use change, competitive pressure and limited genetic diversity at the species level. Naturalised populations in the Driftless Area of the American Midwest may be beneficial for the conservation and agronomic improvement of the species.

Aims: We explored the population structure and genetic diversity of Driftless Area meadow fescue populations, inferring their introduction histories to evaluate their potential contribution to conservation and breeding.

Methods: We assigned plants sampled from 71 grasslands throughout the Driftless Area to genetically defined subpopulations based on neutral nuclear (nSSR) markers. Inter-population hybridisation and genetic diversity were combined with chloroplast haplotype scoring to infer introduction history.

Results: We identified four subpopulations with distinct geographic distributions and haplotype composition, with 28% of sampled individuals representing admixtures of two or more subpopulations. There was moderate differentiation among subpopulations and sampling sites, with nonetheless high within-site diversity. Three chloroplast haplotypes were detected, occurring in different frequencies among subpopulations. Subpopulations appeared to have been derived from separate introductions of heterogeneous genetic material.

Conclusions: Driftless Area meadow fescue populations are unlikely to contribute to conservation of locally adapted European varieties, but represent a valuable resource for the development of novel varieties and for preserving species-level genetic diversity.