C. Moran

Summary Three informative pig F 2 families based on European Wild Boar (W), Meishan (M) and Pietrain (P) crosses have been used for genome‐wide linkage and quantitative trait loci (QTL) analysis. Altogether 129 microsatellites, 56 type I loci and 46 trait definitions (specific to growth, fattening, fat deposition, muscling, meat quality, stress resistance and body conformation) were included in the study. In the linkage maps of M × P, W × P and W × M families, average spacing of markers were 18.4, 19.7 and 18.8 cM, the numbers of informative meioses were 582, 534 and 625, and the total lengths of autosomes measured were 27.3, 26.0 and 26.2 Morgan units, respectively. Maternal maps were on average 1.3 times longer than paternal maps. QTLs contributing more than 3% of F 2 phenotypic variance could be identified at p < 0.05 chromosome‐wide level. Differences in the numbers and positions of QTLs were observed between families. Genome‐wide significant QTL effects were mapped for growth and fattening traits on eight chromosomes (1, 2, 4, 13, 14, 17, 18 and X), for fat deposition traits on seven chromosomes (1, 2, 3, 4, 6, 7 and X), for muscling traits on 11 chromosomes (1, 2, 3, 4, 6, 7, 8, 12, 14, 15 and X), for meat quality and stress resistance traits on seven chromosomes (2, 3, 6, 13, 16, 18 and X), and QTLs for body‐conformation traits were detected on 14 chromosomes. Closely correlated traits showed similar QTL profiles within families. Major QTL effects for meat quality and stress resistance traits were found on SSC6 in the interval RYR1‐A1BG in the W × P and M × P families, and could be attributed to segregation of the RYR1 allele T derived from Pietrain, whereas no effect in the corresponding SSC6 interval was found in family W × M, where Wild Boar and Meishan both contributed the RYR1 allele C. QTL positions were mostly similar in two of the three families for body conformation traits and for growth, fattening, fat deposition and muscling traits, especially on SSC4 (interval SW1073‐NGFB ). QTLs with large effects were also mapped on SSC7 in the major histocompatibility complex (MHC) (interval CYP21A2‐S0102 ) and affected body length, weight of head and many other traits. The identification of DNA variants in genes causative for the QTLs requires further fine mapping of QTL intervals and a positional cloning. However, for these subsequent steps, the genome‐wide QTL mapping in F 2 families represents an essential starting point and is therefore significant for animal breeding.

Summary Sus scrofa chromosome 2 (SSC2) linkage maps were generated from three F 2 families involving Meishan (M), Pietrain (P) and Wild Boar (W) crosses and the same 10 marker loci. SSC2 linkage maps were similar between families and correspond to published maps. Quantitative trait loci (QTLs) for carcass traits, daily gain and heart weight were identified on SSC2, especially in the intervals 0–20 and 80–90 cM in the M × P family, the intervals 20–50 and 125–140 cM in the W × P family, and the interval 15–70 cM in the W × M family. QTL presence and position varied among families. QTL effects explained up to 10% of F 2 phenotypic variance. Pietrain QTL alleles were associated with high muscle and heart mass, high daily gain and low fat deposition and Meishan alleles with high carcass fat content. Wild Boar alleles were associated with leaner carcass but lower daily gain than Meishan alleles.

Heritability of characters (e.g. hamuli number) of honeybee workers can be estimated from data obtained from a random sample of colonies from a single population without the need for controlled matings. Formulae are developed for the estimation of relatedness among workers within colonies as a function of number of drone matings with the queen and the relatedness among these drones. Heritability is then estimated by dividing the intraclass correlation of the character by the relatedness among the workers within colonies. Estimates obtained by this method are shown to be considerably less biased than those obtained by analysing data from single-drone inseminations because of the contribution of dominance variance to the covariance of sib workers.

Summary Linkage maps of Sus scrofa chromosome 5 (SSC5) were constructed using up to 10 markers in three informative F 2 families based on Wild Boar (W), Meishan (M) and Pietrain (P) crosses. The map lengths differed among the families. In the M × P family, the MYF5 locus was linkage mapped between SW995 and SW967 . Relatively few quantitative trait loci (QTLs) were observed on SSC5 explaining a maximum of 5.8% of phenotypic variance in the F 2 generation. The presence and position of QTLs were not consistent among families. The Meishan and Wild Boar QTL allele effects were inferior compared with Pietrain allele effects. The additive effects were small and reasonably strong dominance‐effects were observed. QTLs affecting conductivity in the W × M family and food conversion ratio in the M × P family mapped near MYF5 , while the QTL affecting conductivity in the M × P family was located near IGF1 .