Functional trait heritability and local climatic adaptation among grasses: a meta-analysis

Variation in climate has been demonstrated to be a powerful driver of selection and local adaptation among plant populations. Variation in functional traits among populations can also be indicative of the drivers of local adaptation. However, it is not clear to what extent species exhibit consistent patterns of local adaptation as revealed by common, heritable trait–environment relationships among populations. To address this, we conducted a meta-analysis of common garden studies of grass populations to quantify the degree of heritability of several commonly measured functional traits, and whether demonstrated heritability was driven by climate. We found that leaf size, specific leaf area (SLA) and total biomass all displayed strong broad-sense of heritability. Both leaf area and SLA decreased significantly with increasing temperature seasonality among populations within species, while total biomass increased with increasing annual and dry season precipitation, and decreased with increasing precipitation seasonality. These results indicate similar, consistent drivers of local adaptation among species of grasses. Further information on trait–environment relationships within species could greatly improve our ability to predict broad scale patterns in functional diversity across multiple levels of ecological organization. Expanding the range of traits and regions incorporated in common garden research, in the present case by incorporating root traits and Southern Hemisphere taxa, will provide even greater benefits to the fields of restoration, conservation, and global change ecology.