This data package includes microbial community composition data (“Lau and Lennon PNAS microbe data.csv”), soil nutrient data (“Lau and Lennon PNAS N data.csv”), and plant trait data (“Lau and Lennon PNAS microbe data.csv”) presented in Lau and Lennon 2012. These data were collected from a reciprocal transplant experiment in which plant populations that had evolved under dry or wet soil moisture conditions (“Plant_History”) were planted into small pots filled with soil from mesocosms that had experienced 16 months of dry vs. wet soil conditions (“Microbe_History”). Each pot was then either kept wet or dry (“Contemporary_Water”). Column headers for each data file are described below: Lau and Lennon PNAS microbe data.csv “Pot” = Pot in the reciprocal transplant experiment from which the soil sample was collected. “Plant_History” = The plant evolutionary history of the plants in that pot (i.e., whether they represent lines selected for 3 generations under dry or wet soil conditions) “Microbe_Mesocosm” = The mesocosm from which the soil used in the reciprocal transplant experiment was collected. There were 4 mesocosms per long-term soil moisture treatment. “Microbe_History” = Whether the soil used in the reciprocal transplant experiment came from mesocosms that had experienced 16 months of dry or wet soil moisture conditions. “Contemporary_Water” = Soil moisture treatment (wet or dry) applied to that pot during the reciprocal transplant experiment. Wet pots were watered daily. Dry pots were watered only when plants began to show signs of drought stress. “Fungal_Richness” = The number of fungal Operational Taxonomic Units identified in the sample with T-RFLP. “Bacterial_Richness” = The number of bacterial Operational Taxonomic Units identified in the sample with T-RFLP. “Fungal_Abundance” = The number of fungal gene copies estimated with qPCR. “Bacterial_Abundance” = The number of bacterial gene copies estimated with qPCR. “F_B_Ratio” = “Fungal_Abundance” / “Bacterial_Abundance” “F_PCoA_1” = First principal coordinate describing fungal community composition based on Bray-Curtis distance matrices derived from relativized fluorescence data. “F_PCoA_2” = Second principal coordinate describing fungal community composition based on Bray-Curtis distance matrices derived from relativized fluorescence data. “B_PCoA_1” = First principal coordinate describing bacterial community composition based on Bray-Curtis distance matrices derived from relativized fluorescence data. “B_PCoA_2” = Second principal coordinate describing bacterial community composition based on Bray-Curtis distance matrices derived from relativized fluorescence data. Lau and Lennon PNAS N data.csv “Mesocosm_Source” = The mesocosm from which the soil used in the reciprocal transplant experiment was collected. There were 4 mesocosms per long-term soil moisture treatment. “Plant_History” = The plant evolutionary history of the plants in that pot (i.e., whether they represent lines selected for 3 generations under dry or wet soil conditions). “Microbe_History” = Whether the soil used in the reciprocal transplant experiment came from mesocosms that had experienced 16 months of dry or wet soil moisture conditions. “Contemporary_Water” = Soil moisture treatment (wet or dry) applied to that pot during the reciprocal transplant experiment. Wet pots were watered daily. Dry pots were watered only when plants began to show signs of drought stress. “NO3” = Soil nitrate concentration estimated from KCl extraction followed by analysis on a Flow Solution IV Analyzer. “NH4” = Soil ammonium concentration estimated from KCl extraction followed by analysis on a Flow Solution IV Analyzer. “TIN” = Total inorganic nitrogen = NO3 + NH4 Lau and Lennon PNAS N data.csv “Pot” = Pot in the reciprocal transplant experiment. Four plants (2 from wet-adapted populations, 2 from dry-adapted populations) were planted into each pot. “Plants” = Denotes that all pots included in this dataset were from mixed plantings (i.e., each plot contained both dry-adapted and wet-adapted plant populations. “Microbe_History” = Whether the soil used in the reciprocal transplant experiment came from mesocosms that had experienced 16 months of dry or wet soil moisture conditions. “Microbe_Mesocosm” = The mesocosm from which the soil used in the reciprocal transplant experiment was collected. There were 4 mesocosms per long-term soil moisture treatment. “Contemporary_Water” = Soil moisture treatment (wet or dry) applied to that pot during the reciprocal transplant experiment. Wet pots were watered daily. Dry pots were watered only when plants began to show signs of drought stress. “Plantlocation” = Location within the pot (one of four quadrats). “Plant_Mesocosm” = The plant population from which the plant was collected from. There were eight populations total. Four had experienced 3 generations of dry soil moisture conditions; four had experienced 3 generations of wet soil moisture conditions. “Plant_History” = The plant evolutionary history of the plants in that pot (i.e., whether they represent lines selected for 3 generations under dry or wet soil conditions). “Planting_Notes” = Any oddities at planting were recorded here. “Germination_Date” = Date of emergence. “Relative_Germination_Date” = Date of emergence compared to all other experimental plants (the first seedling to emerge received a score of 1). “Germination_Notes” = Any oddities at germination were recorded here. “Flowering_Date” = Date of first flower. “Relative_Flowering_Date” = Days to flower, calculated from the date that the first plant emerged. “Leaf_number_at_flowering” = Number of leaves when the plant flowered. “Height_at_flowering” = Height (cm) when the plant flowered. “Flowering_Notes” = Any oddities at flowering were recorded here. “Survival” = Whether plant was “Alive” or “dead” midway through the experiment. “Days_to_flower” = “Relative_flowering_date” – “Relative_germination_date” “Fruiting_Notes” = Any oddities at fruiting were recorded here. “Fruit_number” = Total number of siliques produces per plant. “Final_height” = Height (cm) at harvest. Plants were harvested when siliques were ripe. “Thrip_damage” = A qualitative estimate of the amount of leaf area damaged by thrips (0-3). “Flower_number” = Total number of flowers produced, estimated from flower scars. “Plant_stage_at_experiment_end” = Phenological stage at experiment end. Most plants were harvested as the senesced, but we ended the experiment before all plants had completely senesced. “Harvest_Notes” = Any oddities at harvest were recorded here. “Seed_number” = Total number of seeds produced. “Total_seed_mass” = Total mass (g) of all seeds produced. “Mean_seed_mass” = Average seed mass (mg) = “Total_seed_mass” / “Seed_number” “Aboveground_biomass” = Total mass of aboveground vegetative tissue after drying for 2 days at 60 degrees C.