Intraspecific trait variability in wild populations predicts neither variability nor performance in a common garden

Abstract

Dryland restoration requires plant materials capable of performing well despite difficult growing conditions. Selecting plant materials with higher intraspecific trait variability (ITV) may support successful outcomes by enhancing the performance of those materials in restoration settings. However, maintaining ITV from wild populations is not well understood and requires further investigation if ITV is to be incorporated into native plant materials, which are often developed from wild-collected seed grown in agricultural settings. We used two perennial plant species to explore whether (1) ITV measured at field sites predicts ITV in a common garden, (2) rankings of ITV among populations remain stable over time, and (3) higher levels of ITV promote survival and reproductive effort in a common garden. We measured ITV in specific leaf area and height for Bouteloua curtipendula and Heterotheca villosa at field sites and over 2 years in a common garden, as well as survival and flower production in the common garden. We also calculated climate distance between field sites, where seeds were originally sourced, and the common garden to account for the impact of climatic differences on ITV. We found that (1) ITV measured at field sites did not predict ITV in the common garden, (2) rankings of ITV across populations were inconsistent, and (3) relationships between ITV and performance were rare and differed by species. Our findings indicate that the utility of ITV in wild populations as a predictive tool may be limited.