BCO2 and infection: Inspection of the 261 selected genes in the five old landraces detected 14 (SLC11A1, HOXA11, CAMK4, LEF1, TET2, KDR, CTBP1, GAK, CPLX1, PCGF3, FLT1, BCO2, CHGA, and HTRA1) to be associated with known functions (e.g., female reproductive traits, resistance to infection, bone formation, fat deposition, yellow fat, photoperiod, and recombination rate variation) in sheep in previous studies (Supplementary Data 21 and Supplementary Notes).