All plant species are limited in the range of conditions in which they can live, but most grow across environments that vary in biotic and abiotic conditions. Plant populations of the same species often experience different selection pressures based on where they live, and if this results in populations that are more fit in their home environment than non-local populations, these populations are considered to be locally adapted. Gaining a better understanding of local adaptation has direct impacts on conservation and restoration efforts.
Natural selection varies across landscapes and often produces (1) differences between populations in phenotypic traits, (2) associations between traits and environments, and (3) higher survival and reproduction of local populations. Using a literature review of common garden studies published between 1941 and 2017, we documented the commonness of these three signatures of local adaptation in plants native to North America's Great Basin.
For the experiments that reported one or more of these signatures, we found 95.1 percent of 305 experiments showed among‐population trait differences, and 81.4 percent of 161 experiments showed trait‐by‐environment associations. Local populations had greater survival in 67 percent of 24 experiments, and higher reproductive output in 90 percent of 10 experiments. A meta‐analysis found that variation in eight commonly measured traits was associated with mean annual precipitation and mean annual temperature at the source location, with notably strong relationships for flowering phenology, leaf size, and survival.
Our results demonstrate widespread habitat‐related population differentiation and local adaptation across the Great Basin. Locally sourced plants likely harbor adaptations at rates and magnitudes that are relevant to restoration success, and our results suggest that certain key traits and environmental variables should be prioritized in future assessments of plants in this region.