Supplemental information for the file: "soybean_accession.txt" and "biophysical_bioclimatic_variables.txt"

This documentation prepared by Valerie Collins on 20160928.

==========

soybean_accession.txt

The soybean_accession file includes the PI Number, latitude, longitude, country, and STRUCTURE-identified population of origin for each of the 533 accessions used in this study.

1. PI: "Plant Introduction" or accession numbers from USDA Soybean Germplasm Collection. These numbers can be cross-referenced here (http://soybase.org/snps/download.php) for more information about the accession
2. latitude: geographic coordinate
3. longitude: geographic coordinate
4. country: KOR (Korea), JPN (Japan), CHN (China), or RUS (Russia)
5. STRUCTURE_GROUP: accessions are sorted into population group 1,2, or 3 using the Structure software (http://pritchardlab.stanford.edu/structure.html)
6. Color: Population groups were assigned a color - group 1 is green2 (Mainland South), group 2 is red (Island), and group 3 is blue (Mainland North)

==========

biophysical_bioclimatic_variables.txt

This file includes the Bioclimatic and Biophysical variables examined in this study. Bioclimatic variables were retrieved from WorldClim and include 68 variables, including yearly, quarterly, monthly temperature and precipitation, and altitude. Biophysical variables were retrieved from the ISRIC database, and include:ph x 10 in H20, percentage sand, percentage silt, percentage clay, bulk density in kg/m3, cation exchange capacity in cmolc/kg, and organic carbon content in permilles 

Variables:
1. PI: "Plant Introduction" or accession numbers from USDA Soybean Germplasm Collection. These numbers can be cross-referenced here (http://soybase.org/snps/download.php) for more information about the accession
2. latitude: geographic coordinate reference system (not projected), the datum is WGS84
3. longitude: geographic coordinate reference system (not projected), the datum is WGS84
4. Altitude: elevation above sea level in meters
5 - 7: Temperatures measured in Celsius*100 (23.0 degrees Celsius represented as 230)
8 - 16: Precipitation measured in millimeters
17. Mean_Diurnal_Range: the mean variation between the highest temperature and the lowest temperature on the same days
18. Isothermality (having isothermal properties): an isothermal process is a change of a system in which the temperature remains constant
19 - 71: Temperature measured in Celsius*100 (23.0 degrees Celsius represented as 230)and Precipitation measured in mm
72. Bulk_Density_Topsoil: the weight of a given volume of topsoil, in kg/m^3
73. Bulk_Density_Subsoil: the weight of a given volume of subsoil, in kg/m^3
74. Cation_Exchange_Capacity_Topsoil: the capacity of the topsoil to hold exchangeable cations in cmolc/kg
75. Cation_Exchange_Capacity_Subsoil: the capacity of the subsoil to hold exchangeable cations in cmolc/kg
76. Percent_Clay_Topsoil: percentage of the topsoil composed of clay
77. Percent_Clay_Subsoil: percentage of the subsoil composed of clay
78. Organic_Matter_Topsoil: organic carbon content measured in permilles
79. Organic_Matter_Subsoil: organic carbon content measured in permilles
80. pH_Topsoil: the pH of the topsoil, calculated by: pH × 10 in H2O
81. pH_Subsoil: the pH of the subsoil
82. Percent_Silt_Topsoil: percentage of topsoil composed of silt (silt is fine sand or clay)
83. Percent_Silt_Subsoil: percentage of subsoil composed of silt
84. Percent_Sand_Topsoil: percentage of topsoil composed of sand
85. Percent_Sand_Subsoil: percentage of subsoil composed of sand