Local adaptation is a fundamental phenomenon in evolutionary biology, with relevance to formation of ecotypes, and ultimately new species, and application to restoration and species’ response to climate change. Reciprocal transplant gardens, a common garden in which ecotypes are planted among home and away habitats, are the gold standard to detect local adaptation in populations. This review focuses on reciprocal transplant gardens to detect local adaptation, especially in grassland species beginning with early seminal studies of grass ecotypes. Fast forward more than half a century, reciprocal gardens have moved into the genomic era, in which the genetic underpinnings of ecotypic variation can now be uncovered. Opportunities to combine genomic and reciprocal garden approaches offer great potential to shed light on genetic and environmental control of phenotypic variation. Our decadal study of adaptation in a dominant grass across the precipitation gradient of the US Great Plains combined genomic approaches and realistic community settings to shed light on controls over phenotype. Common gardens are not without limitations and challenges. A survey of recent studies indicated the modal study uses a tree species, three source sites and one growing site, focuses on one species growing in a monoculture, lasts 3 years, and does not use other experimental manipulations and rarely employs population genetic tools. Reciprocal transplant gardens are even more uncommon, accounting for only 39% of the studies in the literature survey with the rest occurring at a single common site. Reciprocal transplant gardens offer powerful windows into local adaptation when (a) placed across wide environmental gradients to encompass the species’ range; (b) conducted across timespans adequate for detecting responses; (c) employing selection studies among competing ecotypes in community settings and (d) combined with measurements of form and function which ultimately determine success in home and away environments. Synthesis. Reciprocal transplant gardens have been one of the foundations in evolutionary biology for the study of adaptation for the last century, and even longer in Europe. Moving forward, reciprocal gardens of foundational non‐model species, combined with genomic analyses and incorporation of biotic factors, have the potential to further revolutionize evolutionary biology. These field experiments will help to predict and model response to climate change and inform restoration practices.

Questions: A robust ecosystem requires a functionally heterogeneous community of organisms with ecological traits that permit broad resource partitioning. Understanding community diversity patterns can help investigate drivers of community assembly and assess restoration success. Do biodiversity patterns differ among grassland communities sown with different ecotypes of dominant species during restoration along a rainfall gradient in the tallgrass prairie of the central US Great Plains?Location: Four field sites across a rainfall gradient within the North American Great Plains: Colby, Kansas (39°23′17.8″N, 101°04′57.4″W), Hays, Kansas (38°51′13.2″N, 99°19′08.6″W), Manhattan, Kansas (39°08′22.3″N, 96°38′23.3″W), and Carbondale, Illinois (IL, 37°41′47.0″N, 89°14′19.2″W).Methods: We applied linear mixed models to assess the effect of dominant species ecotype, year, and location on grassland taxonomic, phylogenetic, and functional diversity.Results: The non‐local grass ecotype (compared to the local ecotype) promoted species richness. In contrast, the effect of the dominant species ecotype on phylogenetic or functional diversity was site‐specific over the 10‐year restoration. Richness decreased across the rainfall gradient from dry to moist sites, and the wettest site had the highest phylogenetic and functional diversity.Conclusions: Our results suggest that abiotic filtering by rainfall is a key assembly mechanism that could predict grassland changes in biodiversity in the early restoration phases. Given the community response across the tallgrass prairie, restoration practitioners should consider the impact of regional sources of dominant species used in restoration when biodiversity is a restoration goal. It is recommended for future grassland restoration to detect gaps and limitations in evolutionary and trait structure that will reveal which diversity components to evaluate.

Grasslands converted to agricultural land use can be reestablished by sowing seeds of native species and temporal dynamics of diversity under altered climate can inform community assembly in the context of global change. We quantified three aspects of diversity (species richness, phylogenetic diversity, and functional diversity) in restored prairie plots sown with different ecotypes of two dominant grass species and manipulated rainfall to understand the relative importance of abiotic filtering and population source of dominant species on community assembly. We also evaluated the contributions of intra‐ and interspecific variations in functional traits across plots sown with different ecotypes of dominant species. Since the fourth year of community establishment, species richness decreased over time as dominant species gradually established. Phylogenetic and functional diversity was unaffected by the ecotypic sources of dominant species during restoration. Experimental drought did not affect species richness, phylogenetic, or functional diversity. Community structure in the grasslands was mainly shaped by intraspecific, within‐population variation in the dominant species rather than by differences in traits among species. Our results showed that intraspecific biotic interactions contribute more than environmental filtering to community assembly in a tallgrass‐dominated prairie ecosystem.

This chapter discusses the study of grassland ecology in the realm of ecological genomics, an integrative field of study aiming to understand the genetic mechanisms underlying responses of plants to their environment. The focus here is on plant response to climate and rainfall as drought can reduce grassland productivity, with cascading effects on ecosystem services. Therefore, understanding the genetic mechanisms of how plants respond to drought can predict the effect of global change on grasslands. Specifically, this chapter describes ecological genomic tools to study grasslands by discovering the functions of genes and the genetic basis of phenotypic variation. Next, we describe using ecological genomics to study adaptation to climate and intraspecific variation in grasses. We review the current literature in grassland ecological genomics, highlight the current focus of research, and identify long-term studies in ecological communities that have gaps in current knowledge. We then show a case study of the dominant grass Andropogon gerardii (big bluestem) as an example of modern ecological genomic analyses. This chapter uses this species to detail the assessment of genotype, transcriptome, and ecological function. Overall, this chapter outlines the study of genomics with the aim of understanding the ecological function and the response of grassland species to their changing environment.

Understanding the context‐dependent nature of diversity‐productivity relationships is essential for predicting community responses to environmental change and informing restoration strategies. We conducted a reciprocal common garden experiment across a rainfall gradient (mean annual precipitation: 500–1200 mm year ⁻¹ ) in the US Great Plains to examine how local ecotypes of dominant grasses [e.g., Andropogon gerardi Vitman and Sorghastrum nutans (L.) Nash] and experimental drought (rainout manipulation) shape diversity‐productivity relationships. We applied generalized linear mixed models to assess the effects of aboveground live biomass, seed source, and rainfall manipulation on grassland species richness, phylogenetic diversity, and functional diversity. Functional diversity was positively correlated with aboveground live biomass at the dry site. Dominant species ecotypes influenced diversity‐productivity relationships in a site‐specific manner. The DRY ecotype reduced species richness as aboveground live biomass increased at the driest and mesic sites while the MESIC‐ecotype increased phylogenetic diversity with rising aboveground live biomass at the mesic site, with no effects observed on functional diversity. We further applied generalized boosted regression trees to assess the relative importance of aboveground live biomass, seed source, and rainfall manipulation in shaping grassland diversity. Across all sites, aboveground live biomass was the strongest predictor of diversity, whereas the effects of seed source and rainfall were weaker and more variable, likely reflecting the dominant role of locally adapted grasses in structuring communities and the limited translation of rainfall manipulation into consistent compositional change. These findings highlight the central role of dominant species attributes in shaping diversity‐productivity relationships and stress the importance of considering local adaptation and site context in restoration and biodiversity‐function research.