A large outbred, advanced intercross population derived from 40 DGRP lines (see FBlc0000504). Forty DGRP lines (DGRP-208, DGRP-301, DGRP-303, DGRP-304, DGRP-306, DGRP-307, DGRP-313, DGRP-315, DGRP-324, DGRP-335, DGRP-357, DGRP-358, DGRP-360, DGRP-362, DGRP-365, DGRP-375, DGRP-379, DGRP-380, DGRP-391, DGRP-399, DGRP-427, DGRP-437, DGRP-486, DGRP-514, DGRP-517, DGRP-555, DGRP-639, DGRP-705, DGRP-707, DGRP-712, DGRP-714, DGRP-730, DGRP-732, DGRP-765, DGRP-774, DGRP-786, DGRP-799, DGRP-820, DGRP-852, and DGRP-859) were crossed in a round robin design, giving 40 F1 genotypes. We crossed females of DGRP-208 to males of DGRP-301, females of DGRP-301 to males of DGRP-303, and so on until females of DGRP-859 were crossed to males of DGRP-208. We placed one male and one female of each genotype into each of 10 bottles, removing the parents after 2 d. For each subsequent generation, we collected 40 males and 40 females from each bottle and randomly allocated them to 10 bottles to minimize genetic drift. Thus, the census size of the Flyland population is n = 800 per generation.