A POPULATION CONSENSUS, PARTIAL LINKAGE MAP OF PICEA-ABIES KARST. BASED ON RAPD MARKERS

We built a ''consensus'' partial linkage map based on RAPD markers usi ng 48 sibships of eight megagametophytes each from a natural populatio n of Norway spruce. A RAPD linkage map for a single individual from th e same population had previously been constructed. Using 30 random dec amers that had yielded 83 RAPD markers in the single-tree map, eight m egagametophytes for each of the 48 sibships were screened. The linkage relationship among markers was estimated considering each family of e ight megagametophytes as a progeny of a phase-unknown backcross mating between a heterozygous mother and a fictitious 'recessive' father. Ma rkers were assigned to windows using LOD = 2.0 and theta = 0.4 as thre sholds, and ordered using a criterion of interval support greater than or equal to 2.0. For eight ''windows'' of recombination selected on t he single-tree map, we investigated the consistency of marker order in the two maps. We adopted restrictive criteria for rejecting co-linear ity between the two locus orders. For each window we imposed the most likely locus order obtained from one data set to the other (and vice v ersa), obtaining two symmetrical log-likelihood differences. We consid ered the hypothesis of colinearity rejected when both symmetrical diff erences were significant (Delta LOD > 3.0). By bootstrapping a subset of markers for each window (highly informative, 'framework' loci chose n on the previous single-tree map using a matrix correlation method) t he sampling variability of the single-tree and population maps was est imated. As expected the population map was affected by a larger variab ility than the single-tree map, Heterogeneity in pairwise recombinatio n fractions among groups of sibship revealed a (possible) alternative genomic arrangement detected within a single recombination window.