Genetic analysis of DNA fingerprints for two lines of chickens divergentlyselected for resistance and susceptibility to a heat stress environment

Two lines of chickens derived from a closed base population by divergent se lection for resistance (line R) and susceptibility (line S) to a heat stres s environment were used to produce DNA fingerprints. Individual DNA samples within line and also mixtures of DNA samples of 5, 10, 15 or 20 individual s per line were cleaved by the Hinf I restriction enzyme and the M13 DNA wa s used as a probe. The objectives of this study were to estimate the variat ions within and between lines in DNA fingerprinting patterns, to evaluate a ssociations between these variations and variations between lines due to th eir performance resulting from selection and to estimate the genetic distan ce between the two lines. Genetic variability indices of 0.62, and 0.64 wer e obtained among individuals of lines R and S, respectively. The band shari ng (BS) level within line R was significantly higher (0.45) than that of li ne S (0.34). The average of BS levels between lines was 0.67. The results i ndicated that line S showed more within-line variation than line R. The dif ferences between lines in genetic variability indices and BS levels were at tributed to the differences between females more than between males. Line a nd sex effects on DNA patterns have been explained by line differences in r esponse to selection and selection intensity. A genetic distance of 0.29 wa s estimated between the two lines. One line-specific band with a frequency le vel of 75% was detected for each line revealing the differential effect of divergent selection. Appearance of the line-specific bands was attribute d to genetic drift and mutation, however the contribution of linkage disequ ilibrium was questionable. The results suggest that DNA fingerprinting patt erns may confidently express the variation among populations with genetic s election experiences.